PRV photos

[DanaMac]

With the recent talk (whining) of PRVs, I thought I'd post a few photos. We have replaced more PRVs this year than ever. Probably close to 20. For the most part, they fail giving high static pressure, and restrict the flow/volume.

Here's a few we replaced.

[Wet_Boots]

Are you seeing any consistent lineup of PRVs? I'm usually able to do without a PRV in the system supply, and have been using the Wilkins BR4, with hopes I can service them as needed.

[DanaMac]

No. There is no consistent PRV. Different plumbers, or different builders. You can also see the old ones in the photo. I don't stock any repair parts for PRVs. Replace 'em only.

[unit28]

I have seen a few that were used around Lake Arlington when I lived in TX.
I would come across 110 psi without a PRV,and that would be for calls to repair blown off mains from the DCVA upstream to the meter side.

[Wet_Boots]

I would mostly see Watts, but I decided to stock a few BR4s because they could be set for higher outlet pressures, if needed. I don't know what will wear out on them, long term.

[Kiril]

With the recent talk (whining) of PRVs, I thought I'd post a few photos. We have replaced more PRVs this year than ever. Probably close to 20. For the most part, they fail giving high static pressure, and restrict the flow/volume.

Here's a few we replaced.

Probably failing because people are using them as water hammer arrestors. Go figure. :laugh:

[ksJoe]

Probably failing because people are using them as water hammer arrestors. Go figure. :laugh:

Sigh....

To minimize the amount of regurgitated clutter in otherwise useful threads, perhaps you two could abbreviate your comments in this cat fight.

I suggest using the following format:

{thread number}:{Post number}:{Paragraph number}

So instead of your post above wasting so much space in this thread, you could have simply replied with:

288734:41:3

And Boots could reply with:

288734:42:1

[Wet_Boots]

Oh, wank off, you peacemaker :hammerhead:

[ksJoe]

Peacemaker? I was aiming for instigator. Or maybe irritant.

[Wet_Boots]

Blessed are the instigators..... :p

[Kiril]

Sigh....

To minimize the amount of regurgitated clutter in otherwise useful threads, perhaps you two could abbreviate your comments in this cat fight.

Actually Joe, my comment was serious and is a perfectly valid, if not the actual, reason for the observed failure.

[Wet_Boots]

PRVs always take hammer, because they will close down before a zone valve (or dishwasher or washing machine) does.

[AI Inc]

since when does a prv close down? It is adjusted manualy.

[Kiril]

PRVs always take hammer, because they will close down before a zone valve (or dishwasher or washing machine) does.

So how does the bypass feature work?

[Wet_Boots]

Questions about a bypass feature are pointless, because no great flow of water can travel through the bypass. As a downstream valve closes, the downstream pressure reaches the set point, and the PRV does its job by containing the higher pressure on the upstream side, said pressure including hammer pressure.

[Kiril]

Questions about a bypass feature are pointless, because no great flow of water can travel through the bypass. As a downstream valve closes, the downstream pressure reaches the set point, and the PRV does its job by containing the higher pressure on the upstream side, said pressure including hammer pressure.

LOL .... in other words you don't know how they work.

AI, your common direct acting PRV works via differential pressure across a diaphragm, causing the valve to open as downstream pressure falls, and close as downstream pressure rises.

The reason why boots continues to avoid answering the question about the bypass is because when downstream pressure exceeds upstream pressure, it opens, allowing flow back through the unit.

Improper sizing of the unit will cause it to fail quicker, and water hammer/cavitation conditions will also cause the unit to prematurely fail. Both can lead to noisy operation of the valve.

That would be the reason why some manufacturers specifically state do not install fast opening/closing valves directly downstream (i.e. close to) a PRV (ex. (http://www.armstronginternational.com/files/products/valves/pdfs/installation/AY-275-A.pdf)). A fast opening valve, resulting in a sudden decrease in downstream pressure, could lead to cavitation. A fast closing valve can lead to water hammer as you well know, which can also damage the PRV when it is exposed to the resultant surge pressure. It could also lead to an upstream water hammer surge due to the PRV closing abnormally fast.

Once you know how a PRV works, it is not difficult to see why you should not be using it as a water hammer arrestor and that it be properly sized. A properly utilized and installed PRV should never see water hammer and/or conditions that can lead to cavitation.

[Mike Leary]

Try this:www.jrsmith.com/faq/water.htm

[Wet_Boots]

But PRVs will continue to be installed near water meters, and home plumbing will not suffer damage because of their installation. That hammer forces don't pass the PRV as the downstream pressure reaches the set point is something of a bonus, but that's just the way it works out, and PRV-equipped home plumbing manages to get by without individual hammer arrestors at washing machines and dishwashers.

PRV bypass flow need only be miniscule in comparison, because the bypass is there for the protection of home plumbing from water expansion caused by the water heater.

By the way, a Wilkins BR4 has no diaphragm. A PRV isn't a diaphragm valve in the usual sense, because it is a spring that is providing the force that makes the device function.

[Kiril]

Try this:www.jrsmith.com/faq/water.htm

Mike, there is no point in arguing with someone who clearly has no logic. If the man cannot see the logic even when it is spelled out to him then he never will.

[Wet_Boots]

Who says arrestors have no function? But again, real world experience trumps textbooks. I have experienced the before and after of water hammer arrestors being installed at a washing machine, and it still wasn't a complete solution, because there was still banging in the plumbing. A PRV quieted the plumbing.

[DanaMac]

Well this might make a little sense in why the PRVs are failing more this year. I was talking with the manager at Ewing today, and apparently Colorado Springs Utilities has adjusted pressure up this year in certain areas of town. But I have replaced PRVs in other districts as well.

[Wet_Boots]

I'm not sure I'll ever see what fails on a Wilkins BR4, since most of the moving parts are sold as a single cartridge assembly.