Pressure Valve
I need some assistance on the type of pressure valve I need for a
subdivision I am working on. I am a land development engineer in NC,
USA.
This situation is that my proposed subdivision will be
served by an 8" city water main that will not meet fire protection
(20psi). The county has a 16" main across the street.
We are
going to tap onto the 16" main with a valve that will "open" only when
the pressure on the city side goes below a certain set amount
(20psi). This will work in a fire situation (or when every one flushes
at the same time).
The flow will be metered by the county and
charged to the city, who will then spread it out to the homeowners in
the subdivision.
My question is this. I am searching the
internet for available suppliers but am getting confused on all of the
options. Am I looking for pressure relief valves, pressure sustaining
valves or a combination of the two?
Sounds like a pressure-sustaining valve to me?
Your pressure
drops, this valve opens up, which instantly boosts your pressure, which
shuts the valve back off- feedback effect. check how they handle that
problem with the valves.
You need to be looking at a modified altitude valve. This valve will
sense the downstream pressure and open when it reaches a low setting,
then close when it reaches an upper setting.
You probably need to
be talking with the Ames/Watts company or other control valve
manufacturer. Giving them the specifics can help them design the
solenoids that you need on the valve to correctly meet your conditions.
It is very much a question of semantics - all the valves referred to are essentially the same piece of kit "hydraulically operated, diaphragm actuated control valves" but with the external control plumbing and springs set up differently. Forget the semantics tell the manufacture what you want it to do. Pressure sustaining valves maintain a constant upstream pressure. Pressure reducing valves maintain a constant downstream pressure. This is what you want. The valve will attempt to maintain a pressure of 20psi. If it is greater it will close if it is less it will open.
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