On Monday, November 13, 2017 at 1:22:55 PM UTC-5, Oumati Asami wrote:
On 14-Nov-17 12:17 AM, wrote:


I found the make but still need to find out the model number.



Home Depot's web site has a lot of them - after you click on the
product - there is a link to "specifications" that might help.
... graphs for flow characteristics; pressure ranges and limits, etc
Here's just one example ..

https://www.homedepot.com/catalog/pd...76134d9f7f.pdf

John T.

Thanks for the link.

I'm not sure how to read the flow rates chart. The legend says it's
based on a 50 psi differential. When the flow rate is zero, the fall off
is zero. So, there is no fall off. In this case, what's the pressure of
the system? Is it 50 psi lower than the input pressure (thus, the 50 psi
differential)?


With no flow the output side is at whatever pressure you've dialed in.
The input side is at whatever the supply pressure is, that is at the
dialed in pressure or above. Eg supply side is 100, output is 60.

Those flow charts show the pressure drop across the valve, when it's
wide open, trying to maintain pressure on the house side. For example,
with a 1" valve, at 50 GPM, there would be a 12 PSI drop. So, if you
had the valve set to 60 PSI, with 100 PSI incoming, it would be
maintaining ~ 60 PSI house side. But if the incoming was 65PSI, you'd
have a 12 PSI drop and only ~53PSI on the other side when it was
delivering 50 GPM.



By the way, what I'm interested in is the output pressure when no valve
is open. I just recall I have never mentioned this before.

The output pressure should be whatever you've set the valve to.
That is unless you have a water heater that fires up and increases
the pressure or something like that.





Now that I'm thinking about this, I wonder how a pressure regulator can
regulate water pressure when no valve is open. A regulator can regulate
water pressure only when at least one valve is open. In such a case, the
regulator limits how much water flows out, thus, regulating the water
pressure. If no valve is open the pressure on both ends of the regulator
must be equal. Am I right?

No. The regulator is a valve that closes in response to the house side
pressure. If you stop drawing water, it slowly closes so that only
enough water enters to raise the house side to the desired/set pressure.
That's the whole point, to avoid having high pressure, eg 120 PSI on
the house side when the supply side is at 120PSI. You set it to 60,
you get 60.