[Stoves] Pressure calculations

[ajheggie at gmail.com]

On Monday 20 June 2011 18:21:02 Frank Shields wrote:

> Container B is filled with water and opening of container A goes in
> about an inch. Over flow water from A goes into a catch basin under B.
>
>
>
> I can measure the volume of gas captured in A by a calibration on the
> side of the clear container or the volume of water captured in the
> catch basin. 

OK I don't see any replies so my thoughts are you already have a pressure 
gauge built in, the height of the water column. Thus you can deduce the 
volume at atmospheric pressure in A.



> but I think there is
> no pressure as the 1/4” tubing is open going into A. Is there a back
> pressure from the water in A on the gas coming out of C? Does the
> height of C relative to A (top or bottom) have any bearings on the set
> up?

C is a sealed container so I don't think so. The pressure in C is dictated 
by the pressure in A because they are connected by the tube, The pressure 
in A is set by the difference in height of the water column between A and 
the surface of B. The surface of B is atmospheric and the top of the 
water column in A is atmospheric minus the height of water up the side of 
A. If A could be totally immersed in B then the inside and outside 
pressure  of A would be equalised when the water level in A is the same 
height as B's. Bear in mind that atmospheric pressure is about 9m (30ft) 
of water so your 0.46m column container only changes in pressure by -5% 
of an atmosphere when full to atmospheric when empty.

Last time I did calcs like this was 53 years ago at school so they bear 
some checking.

AJH