On Monday, November 13, 2017 at 11:25:46 AM UTC-5, Oumati Asami wrote:
On 12-Nov-17 8:34 PM, Retired wrote:
On 11/12/17 7:40 AM, Oumati Asami wrote:
On my water pipe system, there is this bell shape thing with a bolt on
the top. I always thought it a water pressure regulator.

The other day, the engineer of my community came to check my water
system. He said that thing is not a water pressure regulator but a
water pressure reducer. According to him, a water pressure regulator
is a device that would keep output water pressure constant. If the
outgoing water pressure is set to, say, 50, no matter what the main
pressure is, be it 100, 90, 80, or 70 psi, the output is always 50 psi.

A water pressure reducer, according to him, is a device whose output
pressure is affected by the input pressure. If the main pressure is,
say, 80 psi, and the output pressure is set to 50 psi, when the main
pressure is increased to 100 psi, the output pressure would also
increase.

Does he make sense?

No, according to this maker's article, he has it backwards.

"Even if the supply water pressure fluctuates, the *pressure reducing
valve* ensures a constant flow of water at a functional pressure, as
long as the supply pressure does not drop below the valve's pre-set
pressure."

http://www.watts.com/pages/learnAbou...=64#whatiswprv


I read the article. The article says "ensures a constant flow of water
at a functional pressure". I don't know what a "FUNCTIONAL PRESSURE"
means. Is it "constant pressure" or not? That's what I want to know.

It means it maintains the output pressure near what it's set to regardless
of whether the input pressure is at that pressure or much higher. The
whole purpose is to maintain near constant pressure. Again, I believe
your question was whether they work like:

A - Maintains a fixed reduction value, eg 20 psi below whatever the
incoming pressure is. (This is what you say the guy told you) So
if the incoming is 100 and it maintains a 40 drop, you'd have 60
on the house side, but then if the
incoming drops to 70, you'd have 30 PSI out.

B - Maintains a fixed output value, eg 60SI, regardless of incoming
pressure, as long as the incoming is 60+

They work like B, they will keep it close to 60. The A type I've never
seen and if they exist sound pretty worthless when you have the B type
available.