Hi Michael,
I seem to recall gas molecules will expand to fill the void in a close system
or something similar like that which is why the volume of ether should not
matter to a certain degree. I still think if it is under filled the gas could
not make up for expansion space. However, I never did well in physics either.
Enough of this, I am taking my Healey down to my sisterbs house so I can go
for a drive and then swimming!
John
From: michael.salter@gmail.com [mailto:michael.salter@gmail.com] On Behalf Of
Michael Salter
Sent: Sunday, July 6, 2014 12:55 PM
To: john
Cc: Oudesluys; Healey List
Subject: Re: [Healeys] Safety gauge - resolved
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@sbcglobal.net
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@autox.team.net
Sent: Sunday, July 6, 2014 1:10 AM
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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