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Re: Compressed Gas Regulators (was: Carbo-Plus vs. compressed gas)





> Date: Wed, 6 Sep 2000 08:27:03 -0500
> From: "James Purchase" <jpurch at interlog_com>
> Subject: Re: Compressed Gas Regulators (was: Carbo-Plus vs. compressed
gas)
>
> Dave Gomberg wrote:
>
> "3.  Get a regulator that does not dump when the tank empties  (I am
working
> on trying to find these)   OR
> 4.  Include a simple pressure relief device in your system  "
>
   Dave, could you elaborate a bit on these two points, please? What should
a
   hobbyist look for in the specs of a regulator which would indicate that
it
   won't "dump" when the cylinder is close to empty? Is a "two-stage"
regulator
   better for this than a "single-stage" one?

   Thanks,

   James Purchase

From: Madan Subramanian madans at satyam_net.in

This is my first post to the APD infact my second but the first one never
came on line. I am a Marine Engineer and I do handle a lot of compressed Co2
systems used for fire fighting on ships.

"Get a regulator that does not dump when a tank empties" - there is no such
thing - a regulator cannot know when a tank is empty and they are simply not
programmable.

" Is a 2-stage regulator better for this than a single stage one" - The gas
will still dump, though a bit later.

"What should a hobbyist look for in the specs so that it will not dump the
gas" - Look for the operating pressure range mentioned something like -
Input Pressure Min. 10 Kg/Cm2, Max. 40 Kg/Cm2,
Output Pressure 1 Kg/cm2 - 5 Kg/cm2. ( an example only -)

" Include a pressure release system" - You can add a spring loaded relief
valve in a parallel branch in your CO2 line set to lift at 20% above the
lower input pressure of your regulator.

If You feel that as per the above example you don't want Co2 at 14 Kg/Cm2
venting into your house well, then lead the exhaust pipe of your relief
valve outside your house, if you cannot  then a safety valve or relief valve
is
not an answer.
The pressures I have given above are purely as an example and in practise
they may be a lot different, but you still will be venting pressurised gas
into your living room.

Don't want a gas dump into your tank or living room - I can think of only
this -----

"A pressure operated (diaphragm) flow shut off valve" --- this valve uses
the pressure at it's input to act on a metal diaphragm which opens the valve
against an adjustable spring pressure to allow the gas to flow ---  fitted
between the 1st stage and 2nd stage regulator will be your solution. ( I am
talking of 2 separate regulators here and a third pressure operated flow
regulating valve in between them - sure adds to the cost, search, and
installation - but the only solution I can think off. )

The operation of this system is simple - say your first stage regulator
dumps the gas at 10 Kg/Cm2 set your diaphragm valve to shut off flow at 12
Kg/Cm2 pressure.
You'll have to find the three matching devices that will deliver you the
result - I cannot help you with this from here in Bangalore, India.
They are definitely available, try your hardware store or if you are on the
coast get hold of a Ship Chandler and ask to see the ISSA CODE BOOK
 International Ship Suppliers Association Code book ) You will find many
models of these 3 devices listed with full specifications and that will help
you to identify the product you want and source them - just my 2 bits worth.

Caio.
Madan Subramanian
Who is plagued by GA, BA, BGA, HA et al.