[Healeys] Safety gauge - resolved

[Michael Salter]

Hi John,
As I understand it we are dealing with vapour pressure in a closed system.
Simply put as the ether boils the gas produced increases the pressure in
the closed system which in turn increases the boiling point of the ether
resulting in the boiling stopping but higher pressure in the system.
This higher pressure makes the Bordon tube straighten a little causing
deflection of the needle.
Temperature rises more the vapour pressure rises thus the gauge needle
deflects further.
Higher the temperature the further the needle deflects.
Please bear in mind that I failed first year physics!!!

Michael S
BN1 #174



On Sun, Jul 6, 2014 at 3:07 PM, john <jmsdarch at sbcglobal.net> wrote:

> Ether boils at 94.28 degrees F. At that point it would become a gas. If the
> blub is under filled, the void would be occupied by gas. Would not gas
> compress differently than liquid thus causing the gauge to read incorrectly
> (low) if the ether vaporized inside of the blub and line?
>
> John Spaur
>
> -----Original Message-----
> From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of
> Oudesluys
> Sent: Sunday, July 6, 2014 1:10 AM
> To: healeys at autox.team.net
> Subject: Re: [Healeys] Safety gauge - resolved
>
> The amount of ether in the bulb is not very critical. Any fluid has a
> specified vapour pressure at a specified temperature. This is what the
> gauge
> registers, it is a manometer that translates pressure to temperature on the
> scale.
> As vapour pressure is independent from volume the amount of fluid does not
> matter, as long as the bulb and capillary is not completely filled up with
> fluid or if there is no fluid but just vapour.
> Apparently there are several sorts of ether I was told by a chemist. He
> supplied me with some that is normally used in automotive gauges which I
> used for repairing a gauge.
> Kees Oudesluijs
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