[Shop-talk] More compressor questions

[John T. Blair]

At 02:59 PM 8/10/2021, Mark Andy wrote:

 >If I were buying a compressor today and the air requirements were modest, I
 >would be looking HARD at one of the super quiet compressor types that are
 >available now.

Again thanks to everyone.  Mark mentions the harbor freight compressor:

<https://www.harborfreight.com/26-gallon-175-psi-ultra-quiet-vertical-shopauto-air-compressor-57336.html>https://www.harborfreight.com/26-gallon-175-psi-ultra-quiet-vertical-shopauto-air-compressor-57336.html

Looking at it's basic specs, it is only rated at  4.5 SCFM @ 
90PSI.  My compressor
is rated at  9.3 SCFM @ 90 PSI.  I've have used my compressor for everything
from painting cars, sanding, impact hammers, die grinders, and both 
media blasting
cabinets & pressure blasting.  And I'm always running out of air and 
stopping to let
the compressor catch up.

So that brings up more questions:

1. What really controls how much a comperssor can generate, ie. SCFM?

2. What controls how long your compressor can supply air before 
having to start
the motor to refill the tank?  I realize that some air tools use a 
LOT more air, but
I'm speaking for any given tool, not compairing something like spray 
painting to
undoing 5 lugnuts on a car.

3. Why is a bigger tank better?  After the compressor's pressure 
switch kicks on,
doesn't it take longer for the compressor to reach the shut off 
pressure with a
larger tank?

4. How can a 1.7 hp compressor deliver a peek of 175 psi and a 
regulated 155 psi
when my 5 hp can only charge to 125 psi.  I realize part of that is due to the
pressure switch, mine is 110 on - 125 off, but really.  Can I put a 
pressure switch in mine and 175 psi.   I don't really think so.  Is 
this more advertising hype like
when they were rating compressors at their starting current vs 
running current for
hp?  They could get 7hp of of a 110V motor - NOT!

John


John T. Blair  WA4OHZ     email:  jblair1948 at cox.net
Va. Beach, Va                  Phone:  (757) 495-8229

           48 TR1800    48 #4 Midget    65 Morgan 4/4 Series V (B1106)
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