This is an interesting product and paper for those of you with A/C in your
autos. The author (George Goble) can be reached at ghg@ecn.purdue.edu and the
suppliers are:
Peoples Welding Supply at
(317) 743-3839 or (800) 345-6942 [Indiana WATS] or contact
Indianapolis Welding Supply at (317) 632-2446 or (800) 382-9006
[Nationwide WATS].
Here it is, distributed with permission... 1800 lines approx.
Mike G.
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A DROP-IN CFC-12 REPLACEMENT FOR AUTOMOTIVE AIRCONDITIONING
by
George H. Goble
286 W. Navajo
W. Lafayette, IN 47906
ABSTRACT
There currently exists a large number (millions) of automobiles
with air conditioning systems designed to use CFC-12 as the refrigerant
along with plans to produce such systems into the 1992-1995 time frame.
During the 1992-1995 period, new production will transition to HFC-134a
refrigerant based systems or other technologies which offer zero or little
ozone depletion. CFC-12 based systems will finally cease production
around 1995, but they will have a lifetime of about 10 years, extending
the need for CFC-12, or a substitute until the year 2005 or so.
This paper will present a ternary blend of refrigerants which may be
able to be used as a transition refrigerant in CFC-12 designed automotive
air conditioners until HFC-134a and other technologies are able to take over.
Performance, oil miscibility, flammability, toxicity, and testing with a
commercial dehydrant/leak sealant will be discussed.
INTRODUCTION
A ternary blend of HCFC-22, HCFC-142b (chlorodifluoroethane), and
small amount of R-600a (isobutane) has been found to provide acceptable
operation on several automobile airconditioning systems designed for use
with CFC-12. Some capacity increase has been noted in most systems, probably
from the blend being non-azeotropic, leading to better utilization of the
condenser and evaporator [1]. This blend features 95% less ozone depletion
potential (ODP) than does CFC-12 (ODP of 0.05 vs CFC-12 with ODP 1.0).
This blend is 55% HCFC-22, 37% HCFC-142b, and 8% isobutane by weight and is
compatible with mineral oils currently used in CFC-12 systems.
Testing began in August 1990 in two vehicles, a 1990 Pontiac
Transsport, and a 1978 Datsun 810. A 1979 Grand Prix was added in
October 1990. By July 1992, some 500 vehicles were running this blend.
Only one failure has occurred. A 1984 Buick Century had a DA-6 compressor
fail. The tear down of the compressor revealed the thin Teflon piston
rings had broken, and fragments had lodged in the valves, holding
them open. Local mechanics state this is an extremely common failure
mode for this compressor (with R-12), and one mechanic reported he
changed 38 DA-6 compressors in a two month period during the summer
of 1991 which had failed for the same reasons. The remaining intact
Teflon piston rings, did not appear to be swollen or affected by
this blend. Currently, there is no reason to suspect this blend
as being the cause of this failure.
The first two vehicles were instrumented with gauge manifolds (all
copper lines) in the passenger compartment along with thermocouple probes,
so temperatures and pressures could be monitored in real life driving
situations. The 1990 Transsport, ran the standard CFC-12 charge for the
first year of its life, it then was charged with the ternary blend. After
8 months no loss of charge was noted from performance and pressures.
Refrigerant has remained clear and dry as observed in an installed liquid
line sight glass.
PERFORMANCE
Testing of this blend has shown significant (around 4F-13F)
decrease in discharge air temperatures at ambient temperatures over 80F
over that of what CFC-12 did. Condensation and evaporation of the refrigerant
appear to occur over a larger band or "glide", thus achieving better
utilization of the evaporator and condenser. At lower ambients, the
capacity (cooling) of this blend drops off to approximately that of CFC-12,
mostly from the reduction in head pressure. Different systems perform
differently. CCOT (orifice) systems generally show more increase in
capacity than do expansion valve systems. Compressor discharge temperatures
did run slightly higher than with R-12. Hot ambients (90-100F) days
produced discharge temperatures in the 180F range. The same systems
had R-12 discharge temperatures in the 160F range (average city driving).
Even though slightly higher, the compressor discharge line temperatures are
still low enough to prevent refrigerant/oil breakdown.
OIL MISCIBILITY
In addition to refrigeration effect, the isobutane makes this
blend miscible in standard mineral oils used in CFC-12 systems. Neither
HCFC-22 nor HCFC-142b by itself are very miscible with mineral oils used in
CFC-12 systems at evaporator temperatures (32F). The "Upflow" evaporators and
large diameter suction lines commonly found in R-12 systems may cause problems
with oil return to the compressor, resulting in compressor failure, when the
refrigerant is not miscible in the oil being used [2].
This blend stayed dissolved in oil (20% oil) by volume, at 32F (approximate
evaporation temperature in auto A/C systems) with Suniso 5GS (525 SUS viscosity)
mineral oil of the type used in auto A/C systems. Suniso 3GS (150 SUS viscosity)
mineral oil (naphthanic) and Virginia KMP 150 viscosity mineral oil (paraffinic)
also stayed dissolved in refrigerant at 32F. Both 150 viscosity oils were
completely dissolved at 0F. Around 10% (by volume) of Suniso 525 SUS viscosity
oil dissolved in the refrigerant at 0F. This 525 viscosity oil is normally used
in auto A/C systems which only operate at 32F or higher. Typically, around 10%
by volume, oil is circulated with the refrigerant in auto A/C systems.
FLAMMABILITY
The current blend could not be ignited, even after a 4 month leak
down test (over 1/2 the charge had been lost). It should be noted that even
CFC-12 can be "flammable", when it contains dissolved oil, and a rapid
release occurs. The oil atomizes into a fine mist and can be ignited.
It has been reported that HCFC-22/HCFC-142b mixtures are nonflammable
up to concentrations of 68% weight of HCFC-142b [3].
Many "nonflammable" refrigerants, which contain hydrogen atoms,
can become flammable if mixed with large amounts of air under pressure.
Such examples include HCFC-22 and HFC-134a. For this reason, this blend
and other refrigerants and blends containing hydrogen atoms should not
be diluted with air, and pressurized (such as for leak testing). Diluting
the refrigerant with dry nitrogen is ok.
Being a non-azeotrope, this blend will change composition during
the leaking process. Recharging (topping off), systems with partial
charges is prohibited. The entire charge must first be removed, and a
recharge done with new (non recycled) material. Repeated topping off of
leaking systems could lead to this blend becoming flammable, thus the
requirement of always doing a full recharge with new material. This
requirement should not impact automotive air conditioning severely. This
difficulty rapidly becomes prohibitive in large commercial systems, where
topping off leaking systems is the normal mode of operation. Non-azeotropic
blends will be cumbersome in anything except automotive and small systems
due to the requirement that the whole charge be removed. Reconstitution
of leaking non-azeotropic blends to known composition is beyond the scope
of almost all service technicians.
TOXICITY
Unlike the new generation of "hyperfluorinated" refrigerants, all
of the ingredients of this blend have existed for decades and their properties
are well known. HCFC-142b is commercially available in large quantities
from Pennwalt (now Atochem), and Kali-Chemie (Germany).
LEAKING AND LEAK SEALING IN CARS
It has been observed, that a large percentage of older (4 years or
older) cars, seem to have continual slow refrigerant leaking problems. Even
when the leaks are identified and repaired, many are low on charge by the
following summer. New leaks form, and/or hose diffusion may be occurring and
may be undetectable due to the large surface areas or difficult to access areas.
Airconditioning service shops, often can only repair "obvious" leaks or change
"bad" components. Some leaks have been observed to be temperature sensitive
(e.g. only leaks in the winter when parts contract) Many cars are continually
recharged at 2 month to 1 year intervals, since the leaks are impossible to
find/repair. Many owners of older cars are not willing to pay the cost of an
entire new system being installed (often over $1000), just because the leaks
cannot be found and repaired. State laws are being enacted (such as Florida,
7/1/91), which prohibit automobiles from leaving a service shop unless the
leak is repaired. If the leak is not repaired, then the CFC-12 must be
removed from the system before releasing the car to the owner. Mechanics
have reported to the author that they have encountered certain brands of
connectors which always leak small amounts of charge, even if they are new
and this has led to much frustration as they cannot be properly "fixed".
A commercial dehydrant/sealant, "DRY-PAK" and "CRYO-SILANE" made
by Cryo-Chem International [4], have been tested with this blend at higher
dilutions than their normal product. System drying and sealing of leaks
has been observed to be satisfactory for the three week to 1 year "leak rates".
This also stopped diffusion through hoses and helped prevent composition changes
in the blend due to leaking. Elimination of constant recharging reduces the
"effective" (per car) ODP further. If a car "saves" five additional recharges
in its lifetime, then the effective ODP becomes 0.01 for a 99% reduction in
ozone depletion from CFC-12. The sealant cost per car works out to be less than
$20. Shaft seal leaks are not repaired, but they are reduced. Use of this
sealant requires the system be "dry", with no significant moisture trapped in
the drier. The sealant manufacturer requires that the drier be changed
prior to use. Experience has found this to be true. Using this blend
[with sealant] on "wet" systems (without changing the drier), resulted in
the sealant being neutralized and no sealing action. No harm was caused
be this action other than sealant being wasted. The systems continued
to perform (and leak) normally. Changing the drier and orifice are always
good refrigeration practices. Old driers can have their desiccant bags
break, clogging the system with clay from the desiccant binder.
PROCEDURES
Being a non-azeotropic blend, certain procedures must be followed
to prevent composition changes. The most obvious is that the system must
be "liquid charged", carefully to avoid slugging the compressor. Systems
with partially leaked charges, should be discharged before recharging, to
achieve a known composition. This problem is greatly reduced by the addition
of the above sealant. Under the "1990 Clean Air Act", this blend cannot
be vented to the environment after certain dates (mostly in 1992), depending
on the type of service (mobile airconditioning, fixed, size of service shop,
etc). It can be "recovered" (pumped into a tank) with CFC-12 recovery
equipment and returned to the manufacturer to be reclaimed to new standards
or be destroyed, it cannot be reused on site.
CONCLUSIONS
The author believes this blend can be used to keep existing and
future CFC-12 automotive airconditioning systems running until they reach
their normal end of life. This blend may take some pressure off the race to
get HFC-134a, its complex lubricants and field procedures operational, for
retrofitting existing CFC-12 systems which fail in the field. Being a blend,
"custom" refrigerants can be made for extra performance in hot humid climates
with minor system modifications (a high pressure cutout switch). Testing
is currently ongoing in this area. It is possible to deliver subfreezing
air continuously at ambients of 100F (highway driving).
Patent pending.
REFERENCES
[1] Kruse, H. "The advantages of non-azeotropic refrigerant mixtures
for heat pump applications" Int. J. Refrig. 1981 vol 4 May pp 119-125
[2] ASHRAE, 1984 Systems Handbook, pp 29.11
[3] Kuijpers, L., Miner, S., "The CFC issue and the CFC forum at the
1988 Purdue IIR conference", Int. J. Refrig. 1989 vol 12 May pp. 123
[4] Private communication with Packo, J., Cryo-Chem Intl. Inc.
Simplified procedures 8/23/91
SELF-SEALING GHG REFRIGERANT-12 SUBSTITUTE
Observe good refrigeration practices. Make sure the system
is free of moisture. Change the drier out unless you are absolutely
sure the system is dry. Many cars come from the factory with
water saturated driers. A WET DRIER WILL NEUTRALIZE THE SEALANT!
CHANGING THE DRIER IS MANDATORY, as even a few drops of water
remaining in it, will make the product not seal. Pumping vacuum on a
system for days, even micron vacuums, will still leave enough
moisture in the drier to neutralize the sealant.
Evacuate (vacuum) the system at least 30 mins (more if possible)
at 29.5 inches (sea level) of vacuum. If possible, evacuate from
both high and low sides of the system, it goes faster.
Determine the amount of refrigerant to charge. If you are
using a "volume" method (Dial-a-charge) or measuring cylinder,
use the same amount of liquid as R-12. If you use "weight"
(scales) use 80% of the R-12 weight you would use.
THIS PRODUCT MUST BE LIQUID CHARGED to avoid it separating out
(sealant will get left behind if vapor charged and mixture will change).
Many automatic charging stations, measure up an amount of
refrigerant, and slowly charge it as liquid (the hose may
frost up if liquid charging). This is ok.
If you use a manifold (gauges) to charge from a tank on scales,
a measuring cylinder, or charge by "feel", then liquid charge
the LOW SIDE in SMALL INCREMENTS on the running system.
Open the refrigerant valve only for 1/2 second or so
(or 2-3 seconds if charging a GM CCOT "accumulator" type
system) and close it for 10-15 seconds or until the low
pressure gauge stops dropping. This boils the liquid
in the hose and avoids slugging the compressor.
On site glass systems, the point where the bubbles just
disappear is the correct charge (add 3-4 more oz if you want).
To speed up charging, if done manually, one can charge in most
(and maybe all) of the liquid, to the evacuated system (engine off),
preferably to the HIGH SIDE. CLOSE THE MANIFOLD HIGH SIDE VALVE
and start the engine & A/C. Charge any remaining charge into the
LOW side as above. "Precharging" the entire charge into the
evacuated system LOW SIDE (before starting the A/C) could wash
away the oil from the compressor on startup.
DO NOT USE A MIXTURE OF AIR AND REFRIGERANT as a leak checking
tool. Some common "nonflammable" refrigerants, such as R-22,
can burn or explode if mixed with large quantities of air under
high pressures. Electronic leak detectors will work with this blend.
DO NOT "TOP OFF" a system low on charge (due to leaking) up to full
charge with this product. The remaining charge must
first be removed, down to zero PSIG (preferably evacuate also),
and a complete new recharge must be done. FAILURE TO HEED THIS,
will cause an unknown composition of refrigerant, poor performance,
and possible flammability problems.
After charging with this or any other R-12 substitute, one
SHOULD ALWAYS PLACE A LABEL on the equipment to state what
kind of refrigerant it contains.
Automotive refrigerants must be recovered or recycled after
1/1/92, because of the "1990 clean air act". Nonaezotropic blends,
including this product, should not be "recycled" on site (cleaned
and reused), but should be "recovered" (pumped into a tank) and
returned to the mfgr to be reclaimed to proper composition or be
destroyed. Penalties up to $25,000 may result from "1990 clean
air act" violations.
Special note for "seal-sealing" product:
The self-sealant should seal slow leaks (except shaft seals) in
a week or so and seal new leaks as they form. A guideline is that
the system should be able to hold a charge for 3-4 weeks or longer
for this product to seal the leaks. Old deteriorated hoses may
not seal leaks which are not in the end connectors. Try to get
about an hour of run time on the A/C unit for each of the first
2 or 3 days after self-sealing product is installed. For the next
week or so, run the A/C whenever the car is driven, adding heat
if it is too cold. The sealant may fail if the temperature is
consistently below 60F. For best results, clean off the oil slick
around or on the leaking hose or area with degreaser or soap and
water (with the system under pressure).
The "tank" pressure for this product is around 82 PSIG at 70F and
35 PSIG at 32F. (R-12 is 70 PSIG at 70F)
Patent Pending.
For more info, see the "Technical Data sheet" for this product.
If you have any questions, contact Peoples Welding Supply at
(317) 743-3839 or (800) 345-6942 [Indiana WATS] or contact
Indianapolis Welding Supply at (317) 632-2446 or (800) 382-9006
[Nationwide WATS].
Simplified procedures 8/23/91
GHG REFRIGERANT-12 SUBSTITUTE [non Self Sealing]
Observe good refrigeration practices. Make sure the system
is free of moisture.
Evacuate (vacuum) the system at least 30 mins (more if possible)
at 29.5 inches (sea level) of vacuum. If possible, evacuate from
both high and low sides of the system, it goes faster.
Determine the amount of refrigerant to charge. If you are
using a "volume" method (Dial-a-charge) or measuring cylinder,
use the same amount of liquid as R-12. If you use "weight"
(scales) use 80% of the R-12 weight you would use.
THIS PRODUCT MUST BE LIQUID CHARGED to avoid it separating out
(The composition will change if it is vapor charged)
Many automatic charging stations, measure up an amount of
refrigerant, and slowly charge it as liquid (the hose may
frost up if liquid charging). This is ok.
If you use a manifold (gauges) to charge from a tank on scales,
a measuring cylinder, or charge by "feel", then liquid charge
the LOW SIDE in SMALL INCREMENTS on the running system.
Open the refrigerant valve only for 1/2 second or so
(or 2-3 seconds if charging a GM CCOT "accumulator" type
system) and close it for 10-15 seconds or until the low
pressure gauge stops dropping. This boils the liquid
in the hose and avoids slugging the compressor.
On site glass systems, the point where the bubbles just
disappear is the correct charge (add 3-4 more oz if you want).
To speed up charging, if done manually, one can charge in most
(and maybe all) of the liquid, to the evacuated system (engine off),
preferably to the HIGH SIDE. CLOSE THE MANIFOLD HIGH SIDE VALVE
and start the engine & A/C. Charge any remaining charge into the
LOW side as above. "Precharging" the entire charge into the
evacuated system LOW SIDE (before starting the A/C) could wash
away the oil from the compressor on startup.
DO NOT USE A MIXTURE OF AIR AND REFRIGERANT as a leak checking
tool. Some common "nonflammable" refrigerants, such as R-22,
can burn or explode if mixed with large quantities of air under
high pressures. Electronic leak detectors will work with this blend.
DO NOT "TOP OFF" a system low on charge (due to leaking) up to full
charge with this product. The remaining charge must
first be removed, down to zero PSIG (preferably evacuate also),
and a complete new recharge must be done. FAILURE TO HEED THIS,
will cause an unknown composition of refrigerant, poor performance,
and possible flammability problems.
After charging with this or any other R-12 substitute, one
SHOULD ALWAYS PLACE A LABEL on the equipment to state what
kind of refrigerant it contains.
Automotive refrigerants must be recovered or recycled after
1/1/92, because of the "1990 clean air act". Nonaezotropic blends,
including this product, should not be "recycled" on site (cleaned
and reused), but should be "recovered" (pumped into a tank) and
returned to the mfgr to be reclaimed to proper composition or be
destroyed. Penalties up to $25,000 may result from "1990 clean
air act" violations.
The "tank" pressure for this product is around 82 PSIG at 70F and
35 PSIG at 32F. (R-12 is 70 PSIG at 70F)
Patent Pending.
For more info, see the "Technical Data sheet" for this product.
If you have any questions, contact Peoples Welding Supply at
(317) 743-3839 or (800) 345-6942 [Indiana WATS] or contact
Indianapolis Welding Supply at (317) 632-2446 or (800) 382-9006
[Nationwide WATS].
Technical Data sheet 8/23/91
GHG REFRIGERANT-12 SUBSTITUTE and
SELF-SEALING GHG REFRIGERANT-12 SUBSTITUTE
GHG REFRIGERANT-12 SUBSTITUTE is a ternary blend of refrigerants that can
be used as a substitute for Refrigerant-12 (CFC-12) in automotive air
conditioning and other medium and high temperature applications.
Ozone depletion is very low, around 1/20 that of R-12 (CFC-12).
The *SELF SEALING REFRIGERANT(tm) blend contains *DRY-PAK(tm) dehydrant
and *CRYO-SILANE sealant from CRYO-CHEM International.
This blend is miscible with mineral oil lubricants used in R-12 systems.
Oil miscibility (refrigerant and oil dissolve in each other) is needed
to insure proper return of the oil to the compressor from the evaporator.
Unlike some other ternary blends, one does not have to flush out the old
oil (spread out over the entire refrigeration circuit) if the oil is
not contaminated from a burnout or other catastrophic failure. Oil
miscibility has been tested down to 0F.
Usage:
Observe good refrigeration practices. Make sure the system
is free of moisture and leaks. Pull a good vacuum (recommended
29.5 inch or better for 30 min or longer). Changing the drier
is highly recommended if the system is over 5 years old or the
system has been open to the atmosphere (no charge remaining).
Old driers may have the dessicant bag break, clogging the system.
Also, remember to "purge" a hose of air/moisture before connecting
it to a system/tank.
If you are using the SELF-SEALING version of this product,
CHANGE THE DRIER RIGHT BEFORE CHARGING unless you are absolutely
sure it is not WET. Any water in the drier WILL neutralize
the sealant. Many cars have wet driers from the factory! It
takes over 30 hours at 90F to partially dry out a wet drier with a
vacuum pump which can pull better than a 200 micron vacuum (29.99
inches), and only 80% or so of the moisture will be removed.
The remaining 20% will still neutralize most of the sealant!
Vacuum pumps typically found out in the field, do not achieve 200
micron or better vacuums, so multi-hour pump downs will not dry out
systems, it will only remove most of the air. Only by changing out
the drier or charging the system with 100% DRY-PAK-12 (to get out
the last 20% of the moisture if the drier is not changed)
will get enough moisture out for the sealant to work. On VIR
systems, remove the dessicant bag, and throw it away, the DRY-PAK
in the blend will remove the residual moisture after the pumpdown.
Systems which are "flooded" with moisture (drier is past its saturation
point, and drops of liquid water are present, may need the drier
changed twice before sealing can occur. This is due to trapped
drops of water in the compressor cylinders which the vacuum cannot
remove, which then migrate to the newly changed drier after a few days.
This moisture is removed when the drier is changed the 2nd time.
* SELF-SEALING REFRIGERANT/SSR/DRY-PAK/CRYO-SILANE are registered trademarks
of Cryo-Chem, International, New Brunswick, GA.
Systems with this much water for over a few weeks, will have had
the refrigerant breaking down into acids, which were eating
away at the aluminum parts, forming sludges, plugging expansion
devices and other general damage. New expansion devices and flushing
the system is highly recommended if this is encountered.
Liquid charging is mandatory to prevent composition
changes which WOULD occur if vapor charging were used.
Liquid charge approx 1/2-2/3 of the estimated charge into the
evacuated system high side. CLOSE THE MANIFOLD HIGH and LOW SIDE
VALVES. If the initial (not running) charge were done to the low side,
then the compressor could slug and/or be starved for oil during the
initial startup due to excess refrigerant washing away oil.
Start the system, and observe pressures and temperatures.
If on a site-glass system, then SLOWLY liquid charge in small
increments to the LOW side until the bubbles start to disappear. If
no site glass, use an electronic site glass, such as a TIF 4000
to determine the absence of bubbles in the liquid line a few
inches before the expansion device (usually near the input to
the evaporator). Hand feel the suction line; if it is getting
cold near the compressor, you have added enough. Adding more
could "slug" (pump liquid) and destroy the compressor. Overcharging
will also cause liquid to back up into the condenser, reduce
efficiency, and cause excessive head pressures. If the suction
pressure goes above 32-40 PSIG or so (fast idle), do not add more
charge, even though bubbles are still detected on the liquid
line. The compressor may be old and be reduced capacity, so
more charge will make it COOL LESS.
For charging by weight, one can use a charge of this product
which is 80% of the R-12 weight specified. For example, a 1990
Pontiac Transsport, A/C system is specified at 3.125 lbs of R-12.
Start with 3.125 X .80 = 2.5 lbs of GHG R-12 Substitute as an
initial charge.
Using a DIAL-A-CHARGE or other "measuring cylinder" (by volume):
A DIAL-A-CHARGE measures volume (not weight) corrected
for temperature of refrigerant. Tests with a DIAL-A-CHARGE
indicate one can use the same volume as with R-12. At 70F, this
product is 82PSIG pressure, but instead use the 70PSIG scale which R-12
would be if it were used. At a given volume on the DIAL-A-CHARGE,
this product will weigh 80% of the same volume of R-12.
In other words, if you would fill a charging (volume measuring)
cylinder to a certain point with R-12, use the same amount of this
product.
If you weigh it with real scales, use 80% of the R-12 amount.
If liquid charging a system where the low side (suction) service
port connects to the compressor or the system has no LOW side
accumulator (most GM/Ford have LOW side accumulators),
BE EXTREMELY CAREFUL to not liquid slug the compressor. Only
open the liquid valve on the manifold for 1/2 second every 15
seconds or so. This allows the liquid to boil off in the manifold
hose and suction lines.
One can also use a "vizi-vapor" charging device (about $30) to
liquid charge the suction line. It atomizes the refrigerant
to prevent slugging. One can also "crack" the manifold
very slightly, and meter in the liquid over a period
of several minutes. Just open it enough so that the low side
pressure rises 10 PSIG or so when liquid is admitted.
If the system has a low side accumulator (GM, FORD),
the liquid manifold valve can be opened for 5-6 seconds
every 30 sec or so during the remainder of the charging process.
The low side accumulator has an "oil hole" which meters oil
and liquid refrigerant back to the compressor at a low rate, as
to not slug it.
A system which is leaking, should be repaired and not "topped off"
with refrigerant when it is low. The refrigerant charge should be
recovered and sent to a reprocessing plant to be destroyed. After
repairing the leak, a complete new charge should be done. FAILURE
TO HEED THIS PARAGRAPH MAY RESULT IN LOW PERFORMANCE AND FLAMMABILITY
PROBLEMS, as this blend will undergo composition changes during
the leaking process. Any non-azeotropic blend of refrigerants will
change composition (and possibly become flammable) if the "leak-
recharge (top off) - leak - recharge" cycle is repeated enough times.
Whenever the system is low on charge due to a slow leak, the remaining
charge must be removed and a complete recharge done to achieve a
known composition.
DO NOT USE A MIXTURE OF AIR AND REFRIGERANT as a leak checking
tool. Some common "nonflammable" refrigerants, such as R-22, R-134a,
can burn or explode if mixed with large quantities of air under
high pressures. This is not all that well known. Dry nitrogen gas
is safe and can be used to dilute refrigerants for leak checking
purposes. Electronic leak detectors will work with this blend.
It is a good idea to avoid "racing" the engine on a very hot
day when running the A/C, when the car is not in motion. Both
this product and R-12 can create very high head pressures
in this situation, sometimes exceeding 400 PSIG. Hoses may
burst or refrigerant may be vented from a relief valve.
On most cars, the "NORMAL" A/C switch setting draws in outside
air, and cools it. "MAX" A/C recirculates the air, so it is
actually "easier" on A/C systems than the "NORMAL" setting,
most of the time.
After charging with this or any other R-12 substitute, one
SHOULD ALWAYS PLACE A LABEL on the equipment to state what
kind of refrigerant it contains. Something of the sort
"Charged with GHG R-12 substitute (blend of isobutane, R-142b,
and R-22), DO NOT RECOVER into same containers as R-12".
R-12 may be mixed with this product in a system, it will work
ok, but there will not be as much performance gain.
Automotive refrigerants must be recovered or recycled after
1/1/92 (7/1/92 for nonautomotive), "1990 clean air act".
Nonaezotropic blends, including this product, should not be
"recycled" on site (cleaned and reused), but should be "recovered"
(pumped into a tank) and returned to the mfgr to be reclaimed to
proper composition or be destroyed. Penalties up to $25,000 may
result from "1990 clean air act" violations.
SECTION FOR SELF-SEALING version of this product
A normal Cryo-Chem SELF-SEALING REFRIGERANT(tm) "kit" costs around
$100/car. It will seal leaks (except shaft seals) of around 1/4 lb/hour
or smaller in a day or less. If you have a leak of this severity,
then you should use a standard Cryo-Chem SSR-12(tm) kit or
repair/reduce the leak, so that it is estimated that the system
would hold a charge for over 3-4 weeks. Once the leak is reduced
to this size, SELF-SEALING GHG REFRIGERANT-12 SUBSTITUTE should be able
to seal it, and future "seepage" leaks, diffusion through hoses, etc.
There is a large class of old cars which need to be "recharged" every
month or so to a year or so. This is the intended market for this
product. To be affordable, SELF-SEALING GHG REFRIGERANT-12
SUBSTITUTE contains a lower concentration of DRY-PAK(tm)
and CRYO-SILANE(tm) than do the standard Cryo-Chem SSR(tm) kits.
Only about $10-$12 per car (for the sealant) is needed instead
of the $100 or so for a full kit. Shaft seal leaks will not be
sealed by this product nor a full Cryo-Chem SSR-12(tm) kit.
Old deteriorated hoses, also may not seal, as they expand/shrink
with pressure changes, breaking loose any seal. End connectors
(they don't swell/shrink as much as the middle of hoses) may
have better success rates.
Some leak sites tend to be covered with oil (esp "permeated" hoses).
If possible wash away the oil with R-11, R-113 (Freon-TF) or
"flush solvent", 1,1,1-trichloroethane, degreaser, or even
soap and water while the system is under pressure. Oil removal
helps the sealing process and allows for future inspection of
the leak sites.
For leaks larger than 1 pound/month (in a 2-3 pound system),
use a Cryo-Chem SSR-12 "kit" (also available from your GHG R-12
distributor). Most of these leaks can be handled by the SSR-12
kits (in a dry system) if the system holds a charge for 2 or 3 days
and does have a shaft seal leak.
The Cryo-Chem SELF-SEALING REFRIGERANT(tm) works by leaking at
the leak site, and upon encountering oxygen and moisture, forms
a type of "epoxy", which seals the leak. The sealant stays in
the system and seals new leaks as they develop. The DRY-PAK(tm)
converts the small amount of moisture that the vacuum did not
remove into silicone oil, which then becomes part of the lubricating
oil in the system. Leaks usually seal in 1-2 weeks.
One should not charge SELF-SEALING GHG REFRIGERANT-12 SUBSTITUTE
into "wet" systems. Doing so, could cause the sealant to activate
(polymerize) inside the system (in the drier). The system will
probably not be "plugged", but expensive sealant will be wasted.
Recommend a good vacuum be pulled for at least 30 minutes before
charging to dry out the system and remove air. THE DRIER SHOULD
ALSO BE CHANGED!
If a system has been open to the air for an extended period of
time, a vacuum of several hours or overnight should be used, as
the oil will have moisture dissolved in it. (this applies for R-12
also). Better still, flush out the system, and add new clean dry
oil.
Many cars (especially American made) have been observed to need
recharging every year or so, even though no leaks can be found
with a sensitive electronic leak detector (0.1 Oz/year setting).
Hopefully, the SELF-SEALING GHG REFRIGERANT-12 SUBSTITUTE can
help most of these cars out.
Additional technical data
This blend has been used in automobiles since August, 1990.
So for, no failures caused by this product have occurred.
Also nothing "bad" like hose or seal failures have been noted.
This blend is a mixture of slightly less than two-thirds R-22
(chlorodifluoromethane), about one third R-142b (chlorodifluoro-
ethane), and a very small amount of isobutane (R-600a), by weight.
The isobutane is obviously flammable (2% - 8% in air by itself),
but it is highly diluted so it becomes nonflammable. R-142b is
"barely" flammable (10% - 16% in air by itself). Dilution by the
R-22 leaves the blend nonflammable.
It has been the position of some automotive companies,
that for fears of liability, that refrigerants, can not contain
any flammable ingredients, even if the "mixture or blend" was
nonflammable. They fear that a slow leak, over a period of time, could
change the composition of the refrigerant to become flammable. A sudden
release of the remaining refrigerant, into the passenger compartment,
during a wreck (rupturing the evaporator, but still containing the
refrigerant to the passenger compartment) could cause a flammability
problem (trapped passenger lights up a cigarette).
A four month "leak down" test was conducted and this blend
could not be ignited with a Bic lighter at the end of a hose slowly
venting some remaining charge. This is only one example though.
More testing is planned in this area. Other companies are currently
undergoing developments on refrigerants with flammable components
(such as R-152a). Standards in this area are constantly changing.
Much of what is currently "accepted" or "rejected" in this arena
is based on speculation of series of almost impossible events, and
is not based on actual tests or experiences. Factors such as
cost, ozone depletion, risks, and liabilities will all have to
be weighed.
Also, one must consider, that in an R-12 closed refrigeration
system, the oil and refrigerant are dissolved in each other.
A sudden release of refrigerant will bring out a fine mist
of oil with it. This oil mist will burn if ignited, even
though mixed only with R-12.
A positive note is that "non-azeotropic" mixtures can result in
significant gains in performance and/or efficiency, over a
single component refrigerant like R-12. Testing of this blend
has shown significant (around 30-40%) increase in cooling at ambient
temperatures over 80F-85F over that of what R-12 did. Condensation
and evaporation of the refrigerant occurs over a larger band or
"glide", thus achieving better utilization of the evaporator and
condenser. At lower ambients, the capacity (cooling) of this blend
drops off to approximately that of R-12, mostly from the reduction
in head pressure. Different systems will perform differently.
Oil miscibility. This product stayed dissolved in oil (20% oil)
by volume, at 32F (approx evaporation temperature in auto A/C systems)
with Suniso 5GS (525 SUS viscosity) mineral oil of the type used
in auto A/C systems. Suniso 3GS (150 SUS viscosity) mineral oil
(napthanic) and Virginia KMP 150 viscosity mineral oil (paraffinic)
also stayed dissolved in refrigerant at 32F. Both 150 viscosity
oils were completely dissolved at 0F. Around 10% (by volume) of
Suniso 525 SUS viscosity oil dissolved in the refrigerant at 0F.
This 525 viscosity oil is normally used in auto A/C systems which
only operate at 32F or higher. Typically, around 10% by volume,
oil is circulated with the refrigerant in auto A/C systems.
Labeling of cylinders and cartons:
Currently, two versions of this product are in production, a
"regular", and the "self-sealing" product. Cylinders/cartons of
the "self-sealing" product will contain a bright green (playing
card sized) sticker to set them apart from the non-sealing version.
A "high performance" version of both regular and self-sealing
is undergoing development and testing now. High performance
cylinders/cartons will carry a bright orange sticker. High performance
self-sealing will carry both orange and green stickers. Initial
tests show that H.P. will deliver 28F air at 100F ambient in
hiway driving and 32-35F in city driving. A mandatory high pressure
cutout switch (about $25-$30) will need to be installed before the
high performance refrigerants can be used.
This product has a "tank" pressure of around 82 PSIG at 70F.
A tank pressure of 7-8 PSIG is obtained at 0F. Pressure is around
35 PSIG at 30F.
Patent Pending.
If you have any questions, contact Peoples Welding Supply at
(317) 743-3839 or (800) 345-6942 [Indiana WATS] or contact
Indianapolis Welding Supply at (317) 632-2446 or (800) 382-9006
[Nationwide WATS].
MATERIAL SAFETY DATA SHEET
IDENTIFICATION:
---------------
Name:
GHG REFRIGERANT-12 SUBSTITUTE and
Self-Sealing GHG REFRIGERANT-12 SUBSTITUTE
Chemical Family:
Halogenated Hydrocarbons + Paraffinic Hydrocarbons + (the refrigerant)
alkoxysilane + amino/alkoxysilane (the sealant)
Formula:
Mixture of C4H10 / CH3CClF2 / CHClF2 (for the refrigerant)
alkoxysilane + amino/alkoxysilane (proprietary to Cryo-Chem Intl) (sealant)
Synonyms:
Methyl propane / R-142b or Isotron-142b or chlorodifluoroethane or HCFC-142b /
R-22 or Freon-22 or Genetron-22 or HCFC-22 (for the refrigerant)
DRY-PAK 22 / Cryo-Silane 22 (SSR-22) (for the sealant)
CAS Name: CAS Registry No.
Isobutane 75-28-5
1-Chloro-1,1-difluoroethane 75-68-3
Chlorodifluoromethane 75-45-6
Manufacturer / Distributor:
Peoples Welding Supply, Inc
426 Brown St Levee
W. Lafayette, In 47906
(317) 743-3839
Emergency phone (24 hr): (800) 535-5053 or (317) 463-2672
PHYSICAL DATA:
--------------
Boiling point: -22 F Percent volatile by volume: 100
Freezing point: Not Established Mol. Wt: approx 90
Density: Not Established Vapor Pressure: 95 PSIA @ 70 F
Vapor Density (Air = 1): Not Established Solubility in H2O: slight
pH Information: Neutral
Appearance and odor:
Colorless liquified gas with faint etheral odor
Self sealing version will have "amine" (dead fish) odor.
HAZARDOUS COMPONENTS
--------------------
Material(s): Approximate weight % :
Isobutane 8
chlorodifluoroethane (R-142b) 37
chlorodifluoromethane (R-22) 55
Volume
Dehydrant/sealant
DRY-PAK (alkoxysilane) 300-600 ppm
CRYO-SILANE (amino/alkoxysilane) 300-600 ppm
HAZARDOUS REACTIVITY
--------------------
Stability:
Material is stable. However, avoid open flames and high temperatures.
Incompatibility (materials to avoid):
Strong oxidants, including oxygen.
Freshly scraped aluminum, Alkali metals, and Alkali earth metals
(sodium, magnesium, etc), may cause exothermic reaction. Aluminum
in refrigeration systems contains an oxide/chloride coating, so
it does not react.
Hazardous decomposition products:
May decompose at high temperatures (above 400F - 500F), and from contact with
hot metal, heating elements, pilot lights, internal combustion engines, and
open flames. Decomposition products may include hydrofluoric and hydrochloric
acids, chlorine, fluorine, possibly phosgene, carbon dioxide, and
carbon monoxide.
Polymerization:
Will not occur. (refrigerant). Self-sealing version will have the sealant
polymerize (300-600 ppm of the total mixture) in contact with with moisture
and oxygen (in air).
FIRE AND EXPLOSION DATA:
-----------------------
Flash Point:
Nonflammable
Autoignition temperature:
N/A
Autodecompisition Temperature:
400 - 500F or above
Fire and Explosion:
Cylinders may vent or rupture in fire conditions, leading to decomposition.
Extinguishing Media:
Nonflammable
Special Fire Fighting Instructions:
Use self-contained breathing apparatus. Use water spray to cool cylinders
to prevent bursting or venting under fire conditions.
Product may be flammable if mixed with large quantities of air at greater
than atmospheric pressure.
HEALTH HAZARD INFORMATION
-------------------------
Principle Health Hazards:
Inhalation: Vapor is heavier than air and can cause suffocation by displacing
oxygen available for breathing. Contact with liquid may cause frostbite.
Breathing high concentrations of vapor may cause light headedness, giddiness,
shortness of breath, and may lead to narcosis, cardiac irregularities,
unconscienceness or death. May cause eye irritation.
Toxicity / Exposure limits:
OSHA and ACGIH Not established, but reccommend TWA 1000 PPM.
Isobutane.
Humans exposed to Isobutane, 500 PPM, 8 hours/day, 5 days/week, for 4 weeks,
showed no cardiac, pulmonary or other functional abnormalities.
Chlorodifluoroethane.
Inhalation - Rat - 4 HR LC50 = 128,000 PPM.
Chlorodifluoromethane.
Low in toxicity at concentrations as high as 4% (40,000 ppm). Narcotic
effects have been seen at 200,000 ppm. Heart effeciency (animal studies)
has been reported to be reduced at concentrations of over 25,000 ppm.
Cardiac sensitization to epinephrine has been observed at concentrations
of 50,000 ppm.
First Aid
---------
Inhalation: Remove to fresh air, call a physician. If not breathing, give
artificial respiration. If breathing is difficult, give oxygen. Do not
give epinephrine or similar drugs.
Note to physicians: Because of possible increased risk or eliciting
cardiac dysrythmias, catecholamine drugs, such as epinephrine, should be
considered only as a last resort in life threating emergencies.
Eyes: Flush immediately with water for at least 15 minutes. Call a physician.
Skin: Flush with water, warm slowly (cool water) if frostbite. Call a
physician.
PRECAUTIONS/PROCEDURES
----------------------
Spill or leak:
Using a self-contained air supply and frostbite protection, personnel should
attempt to close valves or repair the source of the leak, if it is safely
possible to do so. If a large quantity is released, evacuate personnel,
and allow to dissipate.
SHIPPING INFORMATION
--------------------
Proper shipping name: Compressed Gas, N.O.S UN1956
DOT placard: Nonflammable gas
Do not heat above 125F
Other information:
Date revised: 1/08/93
Person responsible: George Goble
Peoples Welding Supply Inc
426 Brown St. Levee
W. Lafayette, IN 47906
(317) 743-3839 or (317) 463-2672
SAFETY PRECAUTIONS FOR REFRIGERANT BLENDS CONTAINING FLAMMABLE COMPONENTS
Currently, there are several refrigerant blends available on the market,
which contain flammable components, but the overall blends are nonflammable.
Some of the flammable components may include isobutane, propane, R-152a,
R-142b (slightly flammable), etc. These are diluted down by other non-
flammable components, leaving the blend nonflammable.
Users of these products should follow certain safety precautions to
prevent accidents, during servicing.
"Topping off" leaking systems should be avoided, as this may force the
particular blend to become flammable, as the components may not all
leak at the same rate. For small systems, the safest way is to recover
the remaining charge into a tank and a recharge done with virgin material.
The recovered charge can then be returned to the mfgr for reclaiming or
sent to a plant to destroy it.
EPA regulations may change with recycling/recovery or recycling/recovery
equipment may be encountered which pulls a system down into a vacuum
(17"-20" or more). When the recovery equipment is disconnected, air
may rush in to fill the vacuum. Meanwhile, the compressor oil is saturated
with refrigerant, and it begins "outgassing", often for several hours.
The oil may outgas flammable components inside the compressor shell
which now has air in it. Using a torch to unsweat the compressor lines
will vaporize oil inside the lines (flammable), in addition to the air
and possible flammable components which may have outgassed from the oil.
This could set up an explosive situation. Even with just using R-12/R-22,
pulling a vacuum, and filling with air, then torch unsweating a line
could still cause ignition.
Purging the system with dry nitrogen or CO2, after refrigerant recovery,
and before unsweating lines greatly adds to safety. Using a pipe cutter
or a hacksaw to remove a compressor is also safer. Brazing/unsweating lines
with refrigerant in them, causes the refrigerant to decompose into
hydrochloric and hydrofluoric acids, carbon scale, etc, which adds to
the contamination in the system.
If a cylinder containing a refrigerant blend containing a flammable
component is found to be leaking, perform a gauge pressure check on it.
If it does not match its required pressure at the current temperature,
then its composition may have changed, and it could possibly have become
flammable. Dispose of the cylinder in accordance with applicable
laws and regulations.
Blends and HCFC/HFC refrigerants (e.g. R-22, R-134a) may become flammable
if mixed with air at greater than atmospheric pressure. One should not
mix refrigerants with air in a system for leak checking or other purposes.
If an internal overload inside an R-22 compressor opens up, which has R-22/air
under pressure, it can cause an explosion, often blowing out the glass plug
where the power wiring enters the dome. Mixing refrigerants with dry
nitrogen for leak checking is ok.
Become familiar with ANSI/ASHRAE standards 15-1989 (Safety Code for Mechanical
Refrigeration) and 34-1989 (Number Designation and Safety Classification
of Refrigerants) and local building codes before using blends with flammable
components inside buildings.
RECOVERY OF GHG REFRIGERANTS (4/15/92)
Since GHG R-12 substitute is a non-azeotropic blend, its composition may
change on leaking. For this reason, this blend and other nonazeotropic
blends cannot be reused. They must not be vented to the environment
if they contain CFCs or HCFCs (e.g.R-12 or R-22). Venting CFCs or HCFCs may
result in EPA fines up to $25,000/day and up to a $10,000 reward for
those who "turn you in".
Use R-12 recovery or recycling equipment to remove any remaining
GHG refrigerant from the equipment. Pump it into its own tank.
"De Minimus" releases of refrigerant are permitted, as long as
"good faith" is used to recover as much refrigerant as possible.
Purging air from hoses before connecting them, and small amount of
vapor escaping when removing hoses, etc, are considered "De Minimus"
releases. Venting the whole charge from an A/C system is not
considered a "De Minimus" release.
Some people feel that the GHG refrigerant vapor remaining in the
recovery/recycling unit will "contaminate" other refrigerant.
GHG refrigerants mix and work well with R-12. The small amount
of vapor left in a recycling unit will not cause any problems
if put back into other cars, provided it is cleaned and dried
properly to remove moisture along with the R-12. If you feel
the need to purge the recycling/recovery equipment, you can hook
up a tank of used R-12 to the recycling/recovery equipment "inlet"
and run it for a few seconds. This will mix some R-12 in with
the recovered GHG refrigerant, and this will not cause any problems.
PLEASE DON'T MIX other refrigerants (except R-12) with recovered
GHG refrigerant.
Commercial refrigerant recovery cylinders are available in various
sizes, from WC (water capacity) 30lbs to 1000lbs or more. These
are similar to "propane" tanks, but have refrigeration valves, and
a slightly higher pressure rating. They are painted gray, with the top
portion being yellow. Recovery cylinders are rated for a working
pressure of 260 PSIG or higher. In contrast propane cylinders are typically
rated at 240 PSIG. You will see a DOT label to the effect of
"4BA260" or "4BW260", the "260" is the working pressure rating of the
cylinder. The "4BA" or "4BW" is the method of tank construction.
ARI standard recovery cylinders are 260 PSIG or higher, since they may
be used for refrigerants R-12, R-22, R-500, R-502, R-114, etc.
R-502 is the highest pressure refrigerant of the group, and it
forces the standard tanks to be a 260 PSIG rating. DOT tanks must
be able to safely contain their contents at 120F. At 120F, the
pressure of R-502 will be around 280 PSIG.
At 120F, the pressure of R-12 or R-12 substitutes will be 160 PSIG
(or less if recovered blend has been leaking). For recovery of
R-12 or R-12 substitutes, at appears to be DOT legal to use a
4BA-240 (e.g. a propane tank) for use as a recovery cylinder, provided
any higher pressure refrigerants (R-22, R-502) are not used.
ARI gray/yellow small recovery cylinders often cost $60 - $200 each.
Propane cylinders (BBQ grill size, 20 lbs propane which is the same size
as the "50lb" refrigrant recovery size, refrigerant weighs more than
propane). The 20lb propane cylinders can often be had for $12-$15/each
at the local "wholesale club". These cylinders usually have a "WC"
(water capacity) of 47-50lbs or so. These can be filled with refrigerant
to 80% of the water capacity. The "TW" (tare weight), stamped on a cylinder
is the "empty" weight. A "CGA-510" "P.O.L" adapter is available
at propane shops or from People's Welding supply, which converts a propane
valve to 1/4" male pipe threads (MPT). Another simple adapter converts
1/4" MPT to 1/4" SAE (refrigeration flare connection) and it is available
at any refrigeration supply house.
Before using a cylinder for the first time, you must insure that it
has a vacuum in it. Some companies ship cylinders with vacuum, some
ship with "dry nitrogen" holding charge, and other use dry air (propane
tanks). A good vacuum pump should be able to evacuate a small cylinder
to 29.5 or 29.9 inches of vacuum in 5 - 10 mins.
When filling a recovery cylinder, you are allowed to fill as follows:
assuming the "50lb" size (either a propane BBQ tank or a ARI recovery cylinder)
TW will be around 18lbs (it will be stamped on the cylinder)
WC will be around 47.7lbs or so (it will be stamped on the cylinder)
You can fill it with 47.7 X .80 = 38.1 lbs of refrigerant.
For the scale reading, you add in the empty weight (TW), so the
scale reading to stop filling at would be 38.1 + 18 = 56.1 lbs.
If a cylinder is filled too full (over 80%), than the liquid may
expand (when it warms up), and cause the cylinder to explode or
the safety (pop-off) to activate.
DOT cylinders used to transport refrigerants, must be hydrostatically
tested every 5 years. There is a "test date" (or new mfgr) date stamped
on the cylinder. If over 5 years has passed, since the last test,
then it is illegal to fill and ship that cylinder. The cylinder's owner
is responsible for having the TESTING done. For a "BBQ grill" propane
tank, it may be easier to just throw it away, and buy another one
for $13 or so at the end of 5 years.
TRANSFERRING REFRIGERANT TO LARGER CYLINDERS.
It may be inconvenient to have large numbers of small recovery cylinders
piling up and having to ship all of them. It may be desirable to
transfer the refrigerant from small "on the job" cylinders to larger
cylinders for eventual shipment.
Propane cylinders (240 PSIG rating) or MAPP gas cylinders (260 PSIG rating)
may be had for $40-$60 new. These usually hold 100lbs propane, which
means they have a WC of 240lbs. They may be filled to 192lbs of refrigerant.
TW is around 69lbs for these cylinders. MAX (gross) fill weight would then
be 192 + 69 = 261 lbs, which will still fit on a bathroom scale.
There are at least 3 ways to transfer refrigerant.
The first is to use your recycler/recovery equipment to vapor transfer it.
This must boil out all the refrigerant from the input tank, recondense it
and put it in the output tank. THIS WILL PROBABLY TAKE HOURS! and it puts
lots of wear and tear on your equipment. The input tank will get cold and
frost up, dropping its pressure, slowing down the recovery. A hot water
bath will help on the input tank.
Second, you can purchase a R-12 "liquid pump" (this is not a compressor),
which will pump liquid from one cylinder to another. The input cylinder
should be set to the "liquid port" or turned upside down if it is a
"vapor only" type to get liquid out. The input cylinder should be located
at the same level or higher than the liquid pump. The pump will "cavitate"
(not pump very well) if it tries to suck the refrigerant uphill. There
is no restriction of the height of the output cylinder. A liquid pump
may be purchased from several suppliers, one of which is National
Refrigeration Products (NRP). Model is "LP12", price is listed as $425.
Their phone number is (215) 639-5885.
The easiest method is to purchase a cylinder heater blanket. Robinair
makes one for about $100, which wraps around a cylinder, and shuts off
around 120F, so it will not overpresurize a cylinder. It uses several
hundred watts of power, quite a bit more than a heater blanket for people.
Refrigerant will migrate to the coldest tank. Put the heater blanket on
the cylinder you want to empty out, and connect both cylinders with a hose.
It will go faster if the "liquid" port is used (or invert the tank if
vapor only) on the tank to empty out. The refrigerant will transfer
in an hour or so to the colder cylinder. On 4/15/92, the Robinair
part number was 10994 (heater blanket), and the price was $104.05.
SHIPPING
People's Welding Supply/Indianapolis Welding Supply or their distributors
will accept recovered GHG refrigrants back in DOT rated "propane" cylinders
or ARI standard (yellow/gray) refrigerant cylinders. Other refrigerant
waste disposal companies will probably not accept "propane" cylinders.
Current regulations specify that recovered refrigerants may be shipped as
"non flammable" "compressed gas". Since recovered refrigerants may contain
large amounts of oil, which dissolves in the refrigerants, the mixtures
in recovery cylinders may be flammable. We have ignited mixtures of
R-12 and oil in tests. People's Welding/Indianapolis Welding Supply
are requesting that all "recovered" refrigerants be returned as "flammable",
due to the unknown amount of oil present, in the interest of safety.
Cylinders need to have a red DOT placard (4" diamond), "flammable gas".
The "proper shipping" name is: Compressed Gas, N.O.S. UN1954
The shipper's certification for hazardous materials must also list the
first two components of the "N.O.S" (Not Otherwise Specified), as being
"chlorodifluoromethane"
"chlorodifluoroethane"
The shipper's certification may be obtained from the company doing the
shipping. All compressed gasses are "hazardous materials".
It should also be known, that many "new" cylinders, both "propane",
and the yellow/gray refrigerant cylinders have been received from
manufacturers with "dirt and grit" in them. This should present no
problem if the refrigerant is being returned to a mfgr to be reclaimed
or to be destroyed. If they are used in a recycler on site, and the
recycled refrigerant is recharged into a system, you may pick up the
dirt, scale, etc, even though your recycler "cleaned" the R-12 first.
Much of this "grit" could wreak havoc on compressor bearings, expansion
devices, etc. When in doubt, one can purchase a refrigeration
"suction filter" (not a suction filter-drier!), which contains a
"feldt element" (no desiccant), which you can put inline in a hose to
catch the grit. Recycler cylinders, sold by Robinair have been tested
as spotlessly clean, but they are expensive.
NOTES ON COMPATIBILITY and RETROFITTING (10/17/92)
Compatibility
With the exception of a homemade Plexiglass (tm) sight-glass which
failed, we haven't seen other evidence of problems caused by GHG
refrigerant. We observed one Aeroquip 1540 hose (about 3 weeks old)
start leaking on a large bus. This was the compressor discharge
hose subjected to extreme vibration. Other Aeroquip 1540 hoses on
the same bus did not fail.
Desiccants
Most automotive A/C systems use a desiccant material in their
"drier" or "accumulator". In the old days, silica gel was used.
Almost all cars on the road use a "molecular sieve" desiccant
as it has better moisture holding properties than silica gel.
It is probably made by a company called "UOP" and is a type called
"XH5-4A" (4 angstrom holes). These are microscopic donuts which
capture moisture.
UOP testing of XH5 desiccants at elevated temps (over 400F) has shown
some increased rates of breakdown when used with R-134a and
"blend" refrigerants. In this case, the "blend" was the DuPont
SUVA (tm) MP33/39/52 series which are blends of R-124/R-152a/R-22
refrigerants. UOP is saying (1991) that they developed a desiccant
called "XH7" for use with R-134a systems, and were developing
a desiccant called "XH9" for the "blends".
Refrigerants for XH5 (e.g. R-12) will work in XH7 and XH9 desiccant
systems UOP stated. Ward Atkinson stated the Dupont blends
(MP33/39/52) needed the XH9 desiccant due to the "action" of the
R-152a on the XH5 material. (GHG has no R-152a). DanFoss, a European
compressor mfgr, found breakdown starting to happen with the DuPont
Suva MP blends in testing (no desiccants in the system) at temps
over 150C (302F) They later pinned it down on the R-152a component of
the blend. If the R-152a has problems above 302F, would this not
mess up the desiccant testing done at over 400F???? It is also
well known, that most chemical reaction rates approximately double
for each increase in temp by 10F. So the small degradations at
400+F testing of some desiccants turn into decades at temps driers
run at in real systems (120-130F max). For mobile A/C, discharge
temps are almost always below 220F, so blends containing R-152a should
not break down. Special single stage low temp equipment should
have compressor discharge temps monitored to be sure they don't
exceed 250F if they use a blend with R-152a. Other refrigerants
(R-12,R-22,R-502,etc) will start break down another 30-40F higher.
Sporlan (refrigeration drier mfgr), has told me that "XH5" equivalent
desiccants showed no problems with R-134a or Suva Blends in practice.
Also their standard refrigeration driers work with R-22/R-502/R-500/R-12,
etc. R-500 is approximately 1/4 R-152a and it does not seem to cause
problems in systems which have run for decades with XH5 equiv desiccants.
Also, automotive driers cut open after two years' service (GHG refrigerant)
had the "BB" desiccant pellets in "like new" shape. There were no signs of
corrosion or "sludge" in the system as would have been the case if
moisture (or acids from refrigerant breakdown) had happened from desiccant
breakdown.
Retrofitting and mixing refrigerants
We have run into tremendous amounts of "misinformation" floating around
in A/C circles. Much of it is obviously "politcally" motivated.
"Buy this, or that will happen". There is lots of pressure to "force"
R-134a retrofits on the public, as there stands much money to be
made ($1000-$1800 estimate for cars, more for trucks, 140 million cars).
Blends will make the "retrofit" easier or into a non-retrofit (just
recharge). Conference proceedings to date have pretty much showed
that it is possible to manufacture NEW R-134a equipment which works
and holds up reasonably well. Retrofitting R-12 systems to R-134a
has been a different matter. The crux of the problem is that R-134a
systems require special oils (PAG polyalkaneglycol or ESTER based)
oils while R-12 systems use mineral oil.
The PAG/ESTER oils are VERY sensitive to contamination from moisture
and chlorine based refrigerants (e.g. R-11/R-113 (flush), R-12, R-22,
GHG R-12 Subs, DuPont SUVA MP33/39/52, and R-176 blends). Conferences
have reported the PAG oils (in R-134a systems retrofitted from R-12)
which contained 1% resisual R-11 (flush), had oil breakdown leading
to compressor failure in less than one week.
Other conference presentations have shown it is almost impossible
(in a scientific lab) to properly clean up a R-12 system in order
to convert it to R-134a. Systems flushed with petrol-ether seven or
eight times still contained a "chloride film" (from the R-12) on
the inside of pipes and hoses, which still caused the breakdown
of the R-134a oils (both PAG and ESTER). Small amounts of mineral
oil still contain dissolved chlorides and R-12, which leads
to the destruction of R-134a oils and leads to compressor failure.
I have yet to see (oct 1992) a R-134a retrofit which worked that did not
involve changing out all the refrigerant containing parts of a system.
This includes changing the evaporator.
Until somebody comes up with an oil which is miscible with R-134a
AND WHICH IS NOT DESTROYED BY TRACE AMOUNTS OF CHLORIDES/CHLORINE
BASED REFRIGERANTS (listed above) R-134a "retrofits" will probably
involve installing a whole new system and removing the old one.
R-134a oil is so sensitive to contamination that the use of R-12
charging hoses, vac pumps, recyclers, gauges, may cause enough
chloride molecules to enter the -134a system to cause it to fail in
a few weeks or months. It has also been reported the PAG oil is
extremely hydroscopic (absorbs moisture) when exposed to the air,
and is very volatile (does not leave telltale oil slicks at leak
spots). We also have a report of techs developing skin rashes
after working with R-134a systems. The recently completed PAFT (sep 92)
test on R-134a revealed that a 5% concentration on RATS led to
testicular tumors with other tests being negative.
The DuPont SUVA MP33/39/52 blends are not miscible (do not dissolve
in) mineral oils, so they need the oil (at least 80% of it) be
changed to a synthetic (alkylbenzene) based oil. "Zerol" is a common
trade name for this kind of oil. Alkylbenzene oils will work fine with
existing refrigerants as well as the Suva MP blends. R-12, R-22, GHG,
R-176 are all miscible in alkylbenzene and will work fine. Alkylbenzene
oils have commonly been used in R-12 and R-22 systems for low temp operation
for years. Do not got to a HVAC supply house and purchase "Zerol"
and use it in a car. It is probably 150 or 300 viscosity. Cars
need around 500 viscosity oils. Currently, SUVA MP33/39/52 blends
call for XH9 type desiccants to be used in the drier. We don't see any
problems with GHG being used with XH5, XH7, or XH9 desiccants.
Also, the SUVA MP33/39/52, GHG R-12 Substitute, and R-176 contain
chlorine based refrigerant blends. Small amounts of one refrigerant
mixed with another one will not cause any problems. GHG R-12 Subs
can be mixed and runs fine with R-12 in a system (mfgr will take
back the recovered refrigerant, even mixed with R-12). Major amounts
of mixing (esp with R-176) may alter pressures some, but no damage
should occur unless the pressures are MUCH higher. In general of
blends, as they leak, their operating pressures become lower due
composition changes, so MUCH higher pressures are unlikely to occur
in practice unless somebody overcharges a system or charges
with straight R-22, etc. If major amounts of SUVA MP33/39/52 (over 30-40%)
are present in a system, then the oil should be alkylbenzene based to
ensure oil return from the evaporator. GHG and R-176 are miscible
(work ok) in mineral oil and/or alkylbenzene oil.
There is much misinformation being circulated on mixing refrigerants.
I have heard some seminars say that your "manifold would blow up"
if you mixed R-12 and R-134a. Bullshit! To sum it up, ONE HAS TO KEEP
R-12, GHG, R-176, SUVA MP33/39/52 out of R-134a systems or the oil
will break down and cause compressor failure. Different fittings
are being designed for R-134a systems for this purpose.
Small amounts of R-134a, GHG, SUVA MP33/39/52, R-176 blends, in
an R-12 system (charged with R-12) should cause no problems.
What about recharging a R-134a system with GHG or other blends?
If this is done, the R-134a oils must be flushed out and replaced
with mineral oil (or alkylbenzene oil if using SUVA MP33/39/52).
Higher capacity would probably result as R-134a systems are
about 30% larger due to -134a's lower effeciency. Once a R-134a
system is charged with mineral oil and (R-12,GHG,SUVA MP33/39/52,
or R-176) one can never go back to R-134a again on that system
since it will have a chloride film which will destroy the -134a oils.
All refrigerants are sensitive to moisture and acid contamination.
Moisture and acids will wreak far more havoc than mixing small
amounts of refrigerant (exception: cannot allow even traces of
chlorine based refrigerants into a R-134a system). If an A/C system
contains aluminum, the acids have already neutralized themselves
by eating away part of the system, so the major problems are water,
sludges (from acids), and air in the refrigerant.
NON-AUTOMOTIVE USE OF GHG REFRIGERANT-12 SUBSTITUTE (8/11/92)
GHG R-12 substitute was designed and tested primarily for automotive
A/C systems. That is the lion's share of leaking CFC-12 to the
environment. There are 225 million cars worldwide which leak 1/2 to
1 lb of CFC-12 each year on the average. 90% of the refrigerant consumed
during the lifetime of a car is for "recharges" and other service, with
10% being used for the initial.
Non automotive uses, do not use nearly the refrigerant for the "service"
sector as does the automotive sector. I have read that only 3% of refrigerators
are ever "opened up" for service. Most are just discarded upon failure.
Also, ternary blends, which are not azeotropes (GHG R-12 subs, R-176, and
DuPont Suva MP33/39/52), cannot be recycled on site, they have to be recovered
(pumped into a tank), and sent to a plant for destruction or reclaiming to
new standards. Nonazeotropic blends change composition upon leaking, so
recharges need to be done with virgin material. "Topping off" a system low
on charge is also prohibited for the same reasons. For the same reasons,
blends will probably be limited to systems with 10lb or less of refrigerant
charge. ASHRAE and other building codes must be consulted as to what
is allowed with refrigerants which are non flammable, but contain
flammable components. You should start with:
ANSI/ASHRAE standards 15-1989 (Safety Code for Mechanical Refrigeration)
and 34-1989 (Number Designation and Safety Classification of Refrigerants)
and local building codes before using blends with flammable components
inside buildings.
DuPont Suva MP39, (R-124/R-152a/R-22) has not finished its toxicity testing
(PAFT) on the R-124. It is expected to be finished around 1995. MP39 also
requires alkyl-benzene based oil (e.g. Zerol) as it is not miscible in
mineral oils used by R-12 systems. A different drier desiccant (XH9 instead
of XH5 molecular sieve, available from Sporlan?) is required for MP39 due
to the action of the R-152a on the XH5 desiccant. Also, DanFoss, a European
compressor mfgr, reported at the Purdue Compressor conference (July 1992),
that they are seeing the breakdown of R-152a (both pure and in blends)
at temps of 150C (302F). They are not really sure of the exact chemistry
going on, but theorize, that minute amounts of moisture in the system
is involved (the water does not get used up by the reaction). Right now,
DanFoss is recommending that compressor discharge temps be kept 10-15C
below the mfgr ratings if you are using anything with R-152a in it.
The R-142b used in GHG R-12 subs, and R-176 has existed for decades, and its
toxicity ratings have been well established. There is no R-152a in GHG.
Experience so far:
Bill Hardaway, in Attica, IN (phone 317-762-2362) has done some testing
with running both "regular" and "self-sealing" GHG R-12 substitute in
nonautomotive use. You may want to contact him for further details.
Head pressure was within +- 15% of the head pressure from R-12.
It depended on what shape the condenser was in (dirt?). Being a blend,
some increase in capacity (forced air condenser) has been noted
(probably due to a "glide" in condensation/evaporation). Compressor amp
draw was the same as R-12. GHG has been run in freezers, and medium and high
temp equipment (beverage coolers, reach-in coolers, etc). Initial
"pull-down" and recovery times seem to be faster than R-12 in much
of the equipment. There have been cases of old R-12 equipment, failing
board of health standards (on recovery time after opening), which have
passed after GHG was used, saving the purchase of $7,000 or so of new
equipment.
The self-sealing version has been used with excellent results in
beverage coolers, etc, with slow leaks. Be sure to remove any driers
first, as water logged desiccant will neutralize the sealant. The
self-sealing contains its own drier which converts moisture to silicon
based oil, and will take it down to 0ppm moisture.
Testing is also being done in ice "storage" boxes, and POP vending
machines with good results being reported so far. An old Whirlpool
"flat plate & wire grid" type ice machine produced uniform thickness
ice plates with GHG.
Since this is a "blend", the evaporation (and condensation) occur over
a small range of temps, instead of at a single temp. (called a "glide")
GHG refrigerant appears to generate "frost lines" similar to R-12 on
medium and low temp equipment, for those of you whom use that method
of charging. For those of you whom use superheat calculations, to
determine charge, we currently recommend using a superheat about
5F higher than with R-12.
Any feedback on nonautomotive use would be appreciated.
George Goble, People's Welding Supply, 426 Brown St Levee, W. Lafayette, IN
47906, 317-743-3839.
UNITED STATES PATENT
5,151,207 [IMAGE AVAILABLE] Sep. 29, 1992 ANS: 1
Drop-in substitute for dichlorodifluoromethane refrigerant
INVENTOR: George H. Goble, 286 W. Navajo, West Lafayette, IN 47906
APPL-NO: 07/638,350
DATE FILED: Jan. 7, 1991
INT-CL: [5] C09K 5/04
US-CL-ISSUED: 252/67; 62/114
US-CL-CURRENT: 252/67; 62/114
SEARCH-FLD: 252/67; 62/114
REF-CITED:
U.S. PATENT DOCUMENTS
4,303,536 12/1981 Orfeo et al. 252/67
4,482,465 11/1984 Gray 252/67
4,510,064 4/1985 Ermak 252/67
4,810,403 3/1989 Bivens et al. 252/67
FOREIGN PATENT DOCUMENTS
2716834 10/1977 Federal Republic of Germany
61-287979 12/1986 Japan
2228739 9/1990 United Kingdom
ART-UNIT: 115
PRIM-EXMR: Christine Skane
LEGAL-REP: Woodard, Emhardt, Naughton, Moriarty & McNett
ABSTRACT:
A novel ternary mixture of refrigerants that can be drop-in substituted for
dichlorodifluoromethane (R-12), but that, unlike dichlorodifluoromethane,
causes very little ozone damage, comprising aproximately 2 to 20% by weight
isobutane (R-600a), approximately 41 to 71% by weight chlorodifluoromethane
(R-22), and aproximately 21 to 51% by weight chlorodifluoroethane (R-142b),
with the weight percentages being of the overall mixture.
6 Claims, No Drawings
EXMPL-CLAIM: 1
SUMMARY:
The present invention relates to refrigerants generally, and more
specifically to a mixture of refrigerants that may be substituted for the
environmentally damaging refrigerant dichlorodifluoromethane (R-12).
BACKGROUND OF THE INVENTION
Butane, isobutane, propane, and other hydrocarbons were commonly used as
refrigerants prior to World War II. The introduction of the family of
FREON.RTM. fluorocarbon products in the early 1930s provided nonflammable,
nontoxic, and what were believed to be environmentally safe substitute
refrigerants for hydrocarbons. Fluorocarbons largely supplanted hydrocarbons
as refrigerants of choice in most applications following World War II.
Hydrocarbons are still in use today in special low temperature refrigeration
systems (-100 degree Fahrenheit) due to the relatively high boiling points of
fluorocarbons.
Certain chlorine containing fluorocarbon refrigerants, known as
chlorofluorocarbons (CFC's), have been causally linked to the well-documented
depletion of the earth's ozone layer. The Montreal Protocol and the United
States Environmental Protection Agency EPA) have thus called for a phase out
of the use of the CFCs that are known to be contributing to the degradation
of the environment, and specifically to ozone layer depletion.
Dichlorodifluoromethane (CCl.sub.2 F.sub.2), also known as CFC-12,
Refrigerant-12, or simply R-12, is one of the most commonly used CFC
refrigerants in automobile air conditioners and elsewhere. It is also the CFC
refrigerant with the highest ozone depletion potential of any known
refrigerant. R-12 has an "ozone depletion units" (ODU) measure of 1.0, and
serves as the yardstick of ozone depletion potential against which all other
refrigerants are measured.
New automobile air conditioners built in 1989 consumed 20 million pounds of
R-12. An additional 80 million pounds of R-12 were consumed that year in
replenishing the R-12 refrigerant that leaked from existing automobile air
conditioners. Leaking of R-12 from automobile air conditioning systems is in
fact a major source of the R-12 that escapes into the atmosphere each year.
Since the discovery in the 1970's that CFC refrigerants escaping into the
atmosphere were depleting the earth's ozone layer, many companies have spent
large sums of money trying to develop a non-toxic, nonflammable replacement
for R-12 that could be "dropped into" existing automobile air conditioning
systems as a substitute for R-12 without requiring any equipment changes. To
date, no such "drop in" substitutes for R-12 have been announced.
Consequently, the automobile industry plans to develop and market new
automobile air conditioning systems by the 1995 model Year that use an ozone
safe refrigerant, tetrafluoroethane (CH.sub.2 FCF.sub.3), also known as,
FC-134a, Refrigerant-134a, or simply R-134a. Fortunately, R-134a has an ozone
depletion factor (ODF) of zero. Unfortunately, R-134a cannot be drop-in
substituted for R-12 in existing air conditioning systems due to compressor
lubrication problems inherent in the use of R-134a in present systems, the
inadequacy of the hoses used in present systems to handle R-134a, and the
necessity of using a larger compressor than is now in use with R-12
refrigerant to Properly utilize R-134a.
Most automobiles that will be built through the 1994 model Year will still
require the use of an R-12 refrigerant, or an acceptable drop-in substitute.
With the environmental efforts to phase out, or ban, the use of
ozone-depleting CFC's gaining momentum, it appears that an R-12 drop-in
substitute for use in existing air conditioning systems must be found.
SUMMARY OF THE INVENTION
The present invention provides a novel ternary mixture of refrigerants that
can be substituted for R-12, but that, unlike R-12, causes very little ozone
damage. It is free of R-12. The novel mixture of refrigerants of the present
invention provides an acceptable level of cooling in medium and high
temperature applications where R-12 is now in use, such as in coolers and air
conditioners operating at evaporating temperatures of 25 degrees Fahrenheit
and higher, i.e., automobile air conditioners. It also mixes well with
compressor oils, thereby providing for adequate lubrication of existing
compressors that utilize R-12. The novel ternary mixture of refrigerants of
the present invention is therefore a "drop-in" substitute for R-12.
One embodiment of the present invention comprises a ternary mixture of
refrigerants that is a drop-in substitute for dichlorodifluoromethane (R-12),
comprising about 2 to 20 weight percent isobutane (R-600a), about 21 to 51
weight percent chlorodifluoroethane (R-142b), and about 41 to 71 weight
percent chlorodifluoromethane (R-22), with the weight percentages of the
components being weight percentages of the overall mixture.
Another embodiment of the present invention comprises a method for producing
refrigeration in a refrigeration system designed for a dichlorofluoromethane
(R-12) refrigerant, comprising drop-in substituting for the
dichlorofluoromethane (R-12) a ternary mixture of about 2 to 20 weight
percent isobutane (R-600a), about 21 to 51 weight percent
chlorodifluoroethane (R-142b), and about 41 to 71 weight percent
chlorodifluoromethane (R-22), with the weight percentages of the components
being weight percentages of the overall mixture; condensing the ternary
mixture; and thereafter evaporating the ternary mixture in the vicinity of a
body to be cooled.
It is an object of the present invention to provide a "drop in" substitute
for R-12 that causes very little ozone damage.
It is also an object of the present invention to provide a substitute
refrigerant for R-12 that has an ozone depletion factor (ODF) of
approximately 0.05.
It is also an object of the present invention to provide a drop-in
substitute refrigerant for R-12 that provides an acceptable level of cooling
in medium and high temperature applications where R-12 is now in use, and
that mixes well with compressor oils that are miscible with R-12 to provide
for adequate lubrication of existing compressors that utilize R-12.
Related objects and advantages of the present invention will be apparent
from the following description.
DETDESC:
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiments described below, and
specific language will be used to describe the same. It will nevertheless be
understood that no limitation of the scope of the invention is thereby
intended, such alterations and further modifications in the described
embodiments, and such further applications of the principles of the invention
as described therein being contemplated as would normally occur to one
skilled in the art to which the invention relates.
The novel ternary mixture of refrigerants of the present invention includes
a mixture of approximately 2 to 20% by weight isobutane (R-600a),
approximately 21 to 51% by weight chlorodifluoroethane (R-142b), and
approximately 41 to 71% by weight chlorodifluoromethane (R-22), with the
weight percentages totalling 100%. This novel mixture of refrigerants is a
drop-in substitute for R-12 in medium or high temperature applications, such
as coolers and air conditioners operating at evaporating temperatures of 25
degrees Fahrenheit and higher.
Compared with R-12's ozone depletion factor (ODF) of 1.0, however, this
novel mixture has an ozone depletion factor of about 0.05, and will be
classified as an EPA CLASS-II substance under the Federal Clean Air Act, as
amended. R-12 is a CLASS-I substance. R-22 and R-142b are not production
controlled or taxed by the EPA or under the Montreal Protocol at this time.
Typical air conditioning compressor operation produces a "fog" consisting of
about 10% compressor lubrication (mineral) oil mixed in the refrigerant
discharge hot gas stream leaving the compressor. The refrigerant typically
condenses to liquid at temperatures of about 100 to 180 degrees Fahrenheit.
The warm refrigerant liquid lowers the viscosity of the oil it is carrying,
so oil build up in the high pressure (liquid) side of the refrigeration
circuit is not a problem. However, after passing through the expansion
device, the refrigerant temperature drops to the 32 to 35 degree Fahrenheit
range and boils back to the gas phase in the evaporator. The oil will thicken
and tend to become trapped in the evaporator if it is not readily miscible in
the refrigerant. The refrigerant leaves the evaporator as a gas, leaving much
of the oil behind, which then starves the compressor of oil and leads
ultimately to compressor failure.
On the the other hand, an oil miscible refrigerant, such as R-12, causes the
oil and refrigerant to mix during the condensation phase. This greatly lowers
the viscosity of the oil during the evaporation phase. Since the oil contains
large amounts of dissolved refrigerant, which is now boiling and foaming, and
is still low in viscosity, the oil gets carried out of the evaporator by the
gas stream. Now in the warm suction line, most of the remaining refrigerant
leaves the oil. Since the gas velocity is higher and the suction line is much
warmer than the evaporator, the oil can find its way back to the compressor
by creeping along the walls of the warm suction line.
R-22 and R-142b are polar substances that have limited miscibility with the
compressor lubrication oils typically used in air conditioning systems
charged with R-12 refrigerant. In testing done to date with samples of R-142b
and R-22 mixed with approximately 10% by volume of a 525 viscosity automotive
refrigeration oil typically used in R-12 systems, both R-142b and R-22 did
not stay mixed with the 525 viscosity oil at evaporation temperatures (35
degrees Fahrenheit). Testing has also shown that R-12 refrigerant and the
novel ternary mixture of the present invention stayed mixed with the 525
viscosity oil, even at 0 degrees Fahrenheit.
It would be possible to use a binary mix of R-22 and R-142b in existing R-12
automobile systems, but the 525 viscosity oil used in R-12 systems would have
to be changed and replaced with an oil designed for use with an R-22
refrigerant. Oils designed for R-22 systems are usually of a viscosity of 150
to 300. To date, no commercially marketed 525 viscosity oil is known to be
miscible with R-22 refrigerants. Due to the extreme conditions automotive air
conditioners sometimes encounter, the use of 150 to 300 viscosity oils may
cause lubrication problems if the oil becomes too thin.
Changing the oil in an existing R-12 system is also time consuming and
costly. Oil is spread out over the entire refrigeration circuit, so draining
the compressor will only get part (usually just 1/2) of the oil in the entire
system. A common method of cleaning the oil from an R-12 system is flushing
the system with trichlorofluoromethane (CCl.sub.3 F), also known as R-11.
This requires the inconvenience of disconnecting the system piping. Also,
R-11 has the same ozone depletion factor as R-12, and it is becoming
expensive and hard to find. Using several pounds of R-11 to flush an existing
R-12 system is therefore environmentally unsound.
The isobutane component of the ternary mixture of the present invention
keeps 525 viscosity oil miscible with the novel mixture of the present
invention at evaporator temperatures, and also provides refrigeration effect
near the output side of the evaporator. Thus, the isobutane component aids in
the oil return from the evaporator back to the compressor, and, in fact, is a
necessary component to prevent lubrication-related compressor failures in
R-12 designed systems.
The small amount by weight of isobutane utilized in the mixture of the
present invention does not appear to cause flammability problems. In
comparison testing with a binary mixture of isobutane and R-22, the R-22
component of the ternary mixture of the invention appeared to leave the
ternary mixture more slowly when a system leak occurred, and did not
concentrate the isobutane to flammable limits. In the binary isobutane/R-22
mixture, by contrast, the R-22 left the binary mixture quickly, concentrating
the isobutane to flammable limits at the leak location.
Table I sets forth examples of ternary mixtures of the invention with known
tolerances to date. Percentages are weight percentages, and components total
about 100%.
TABLE I
______________________________________
Mixture
Isobutane R-142b R-22
______________________________________
A 8%+/-2% 36%+/-2% 56%+/-2%
B 8%+10%-5% 36%+/-10% 56%+/-2%
C 8%+12%-6% 36%+/-15% 56%+/-15%
D 8%+/-2% 28%+/-7% 64%+/-7%
______________________________________
Mixture A has been the most preferred mixture to date. Mixture B would work
in most instances. However, mixtures at the high end of the isobutane range,
and/or the high end of the R-142b range may lead to flammability problems in
standard automobile air conditioning systems designed for R-12. Also,
mixtures at the low end of the isobutane range, and/or the low end of the
R-142b range, may lead to compressor oil starvation (poor oil return) and
excessive system pressures when used in an automobile air conditioning system
powered by an engine that is being revved while the automobile is not in
motion on very hot days (90 degrees Fahrenheit or hotter).
Mixture C will cause flammability problems in standard automobile air
conditioning systems designed for R-12 when the R-142b and/or isobutane
components are at the maximum weight percentages. Low performance or liquid
slugging may also occur. If the weight percentage for R-22 is at the maximum,
high system pressures will occur and lead to hoses bursting or other standard
automobile air conditioning system failures. However, Mixture C may work well
at the high and low ends of the component limits in non automotive systems,
such as household air conditioning systems or heatpumps, in R-22 systems, or
in modified automobile air conditioning systems designed for R-12. Mixture C
may also work well at the high and low ends of the component limits in
standard automobile air conditioning systems designed for R-12 that are
operated only under special conditions, such as at 60 degree Fahrenheit
ambient temperature or lower.
Mixture D represents a high performance mixture that would deliver 50 to
100% more cooling at higher temperatures. Mixture D would require minor
equipment changes to the standard automobile air conditioning system to add a
high pressure cutoff switch to the high side (liquid) line gauge service
port. The recommended cutoff pressure would be 375 to 400 PSIG, with a cut
in pressure of 250 PSIG. Such a switch needs to be installed in series with
the compressor clutch circuit to disable the compressor when the cut out
pressure is reached. Revving an automobile engine while not in motion at an
ambient temperature of over approximately 90 degrees Fahrenheit would cause
the cut out to operate. Engine idle speeds probably will not cause a high
pressure cut out if the condenser is clean. When the vehicle is in motion,
ram air should provide adequate condenser heat dissipation to prevent over
pressure cut outs.
In testing completed to date, the ternary mixture of the invention has
exhibited much better cooling than R-12 at temperatures above ambient
temperatures (70-75 degrees Fahrenheit). On nonexpansion valve air
conditioning systems found in most U.S. made vehicles (orifice only), head
pressure of the ternary mixture of the present invention falls off below
70-75 degrees Fahrenheit, reducing the system capacity to what would be
provided by R-12.
For the purpose of promoting a better understanding of and to further
illustrate the invention, reference will now be made in the Examples below to
preferred ternary mixtures of refrigerants of the invention.
EXAMPLE 1
A mixture of 8.4% by weight isobutane, 35.7% by weight R-142b, and 55% by
weight R-22 was provided in the following manner (the weight percentages add
up to 99.1% due to a measurement error). TIF electronic refrigerant
"charging" scales were used to weigh in the charge. A vacuum was pulled on a
Roninair 4 lb. capacity "dial-a-charge" refrigerant measuring cylinder. The
isobutane (liquid) was weighed into the vacuum in the dial-a-charge. The
pressure was about 26 PSIG at 73 degrees Fahrenheit. The R-142b was then
weighed into the dial-a-charge. R-22 was then weighed in slowly with
intermittent shaking of the dial-a-charge to mix the isobutane and R-22 and
noting of the pressure. R-22 was added in this fashion until the pressure
reading on the dial-a-charge was approximately 7 to 8 PSIG higher than what
R-12 would have been at the temperature of mixing. For this example, at 73
degrees Fahrenheit the pressure of 80 PSIG was used as the stopping point for
adding R-22. R-22 was added over a period of about 20 minutes to allow
temperatures to stabilize within the dial-a-charge.
The dial-a-charge was then removed from the charging manifold/gauges and was
connected to the air conditioning system of a 1978 Datsun 810 and the system
was charged in the conventional manner. The oil in this system already
contained a red dye for leak detection. Samples, under pressure, were taken
with a vizi-charge from the liquid line during operation. The vizi-charge was
then switched to the low (suction line), and the valve slowly opened to boil
off the working fluid in order to observe the amount of oil carried in the
sample. About 10 to 12% by volume of oil was observed after the refrigerant
boiled off. Oil was observed to be still mixed evenly in the vizi-charge
after setting for 3 days.
The mixture within the dial-a-charge was tested for flammability, but could
not be ignited.
Cooling in the 1978 Datsun 810 seemed slightly better than that obtained
previously with R-12, although no detailed BTU measurements were taken.
Suction (low side) and discharge (high side) pressures were close to those
obtained with R-12. At ambient temperatures in the low 70's, low side
pressure was about 11 to 13 PSIG (at 2000 rpm; R-12 would be about 18 PSIG),
and high side pressure was about 150 PSIG. Momentary high side pressures were
obtained around 200 PSIG with a hot engine, stopped at traffic lights, with
the ambient temperature in the high 70's. This is close to the high side
pressures of R-12.
The air outlets within the automobile were emitting chilled air in the 38 to
40 degrees Fahrenheit range, and the compressor was cycling on and off due to
the low temperature cut out being reached. The 1978 Datsun 810 has the
receiver (storage tank) in the high pressure side rather than in the low side
as found in typical General Motors systems. The lower suction pressures
seemed to be due to the evaporator being colder by 5 to 7 degrees Fahrenheit
than was the case with R-12.
EXAMPLE 2
Additional testing of the mixture of Example 1 was done in a 1990 Pontiac
Transsport equipped with a Harrison (GM) "V-5" variable displacement
compressor. This compressor reduces its displacement (capacity) when the
suction pressure drops below 28 PSIG. Compressor gas discharge temperatures
appeared to be close at idle with an ambient temperature of 87 degrees
Fahrenheit to those of an identical model 1990 Pontiac Transsport at a new
car dealer that utilized standard R-12 refrigerant. The R-12 system idled at
150 degrees Fahrenheit and the mixture of Example 1 idled at 154 degrees
Fahrenheit.
Head (high side) pressures for the mixture of Example 1 were lower than in
the R-12 system when the vehicles were in motion (30 to 65 MPH), ranging from
220 to 150 PSIG at an ambient temperature in the low 90's. Racing the engine
(2000 to 3000 RPM) while parked caused slightly higher head pressures than
the R-12 system. The R-12 system with MAX-AIR engaged was able to reach 400
PSIG at an ambient temperature of 100 degrees Fahrenheit, but the mixture of
Example 1 reached 400 PSIG at an ambient temperature in the low 90's. This
appears to be due to the fact that more heat is transferred and the condenser
is less able to get rid of the heat with no ram air. At normal idle speeds
and an ambient temperature of 95 degrees Fahrenheit, head pressures of around
250 to 260 PSIG were observed, well within system limits.
Increasing the weight percentage of R-22 in the mixture of Example 1 tends
to drive up head pressures and also moves more heat, leading to cooler
discharge air. Idle performance with a higher R-22 weight percentage produced
pressures approaching design limits at ambient temperatures of 95 degrees
Fahrenheit or above. A pressure limiting cut out switch that would be
connected t the high side service valve and would be used to disengage the
compressor if high idle or racing the engine while parked raised pressure too
high (i.e., 375 PSIG) would provide much superior cooling performance during
normal operation. Cooling would be between 50% to 100% more than a comparable
R-12 system.
Lowering the weight percentages of R-22 in the mixture of Example 1 reduced
the cooling capacity and lowered head pressure while raising suction
pressure. On nonvariable displacement compressors, the suction pressure would
be expected to decrease instead of increase in this case. This moved the
mixture toward increased flammability as well. Head pressures dropped
significantly with the vehicle in motion to the point of reducing refrigerant
flow through the expansion device, which greatly reduced cooling.
While the invention has been described in the Examples and foregoing
description, the same is to be considered as illustrative and not restrictive
in character, it being understood that only preferred embodiments have been
described and that all changes and modifications that come within the spirit
of the invention are desired to be protected.
CLAIMS:
What is claimed is:
1. A ternary mixture of refrigerants that is a drop-in substitute for
dichlorodifluoromethane refrigerant in dichlorodifluoromethane refrigeration
systems, comprising about 2 to 20 weight percent isobutane, about 21 to 51
weight percent 1-chloro-1, 1-difluoroethane, and about 41 to 71 weight
percent chlorodifluoromethane, with the weight percentages of said components
being weight percentages of the overall mixture.
2. The ternary mixture of refrigerants of claim 1 in which isobutane is
present in about 6 to 10 weight percent, 1-chloro-1, 1-difluoroethane is
present in about 21 to 35 weight percent, and chlorodifluoromethane is
present in about 57 to 71 weight percent, the weight percentages of said
components being weight percentages of the overall mixture.
3. The ternary mixture of refrigerants of claim 1 in which isobutane is
present in about 3 to 18 weight percent, 1-chloro-1, 1-difluoroethane is
present in about 26 to 46 weight percent, and chlorodifluoromethane is
present in about 46 to 66 weight percent, the weight percentages of said
components being weight percentages of the overall mixture.
4. The ternary mixture of refrigerants of claim 3 in which isobutane is
present in about 6 to 10 weight percent, 1-chloro-1, 1-difluoroethane is
present in about 34 to 38 weight percent, and chlorodifluoromethane is
present in about 54 to 58 weight percent, the weight percentages of said
components being weight percentages of the overall mixture.
5. The ternary mixture of refrigerants of claim 1 in which said mixture is
miscible with refrigeration oils that are miscible with
dichlorodifluoromethane.
6. The ternary mixture of refrigerants of claim 5 in which the weight
percentage of isobutane renders the mixture miscible with refrigerants oils
that are miscible with dichlorodifluoromethane.
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