Water hammer damage (photos, please) - LawnSite.com™

Wet_Boots · #1 10-24-2010, 11:13 AM

The subject of water hammer has been kicked around here as of late. I, for one, would be interested in some photos of damage that can be directly attributed to water hammer. With them, could go the information on the static pressure, and length of supply line leading to the valve that did the hammering.

For myself, I can contribute little. I've never had upstream plumbing damaged from water hammer. The only upstream event I can recall involved a customer wanting me to reuse all the original system components, including an Orbit master valve (first time I ever dealt with one of them) - said Orbit valve blew off the 1-inch copper male adapter less than a week after the renovation. 100 psi static pressure, and less than 80 feet from street to master valve. A Richdel 205F took its place, and no more was ever heard from the master valve.

DanaMac · #2 10-24-2010, 11:19 AM

Years ago, when I was young and green, I had a PVC manifold repair call. Rebuilt it, got a call back a few days later that it cracked again. Rebuilt it, call back again that it cracked. The system was all RB DV-100s. I told them I would rebuild it if they paid for new valves. I installed either 2400s or 205, don't remember which. And never had a problem again.

When I was still an employee, we installed a system at a home that had no PRV before the meter. Once we got it installed and started going through zones, turned the controller to off to finish clean up. Heard the homeowner screaming a couple minutes later. The bottom of the water meter exploded out. I don't remember it it was plastic or metal. Once again, RB DV-100s.

Wet_Boots · #3 10-24-2010, 11:27 AM

Gee, I would hope they don't have plastic bottom plates on water meters. Those are supposed to be the indestructible items you can rely on. What water pressures were you dealing with? Long supply runs?

That does make me recall one similar event, where some basement plumbing wasn't secured to the wall as tightly as it could be, and sure enough, the bottom plug on a PRV blew out. The way the plumbing was, that plug was the point of contact where the unsecure plumbing could bump against the basement wall.

DanaMac · #4 10-24-2010, 11:32 AM

Quote:

Originally Posted by Wet_Boots

Gee, I would hope they don't have plastic bottom plates on water meters. Those are supposed to be the indestructible items you can rely on. What water pressures were you dealing with? Long supply runs?

A lot of the newer meters have a plastic/PVC style bottom. We can typically see static pressure between 100 and 150 psi without a PRV. A couple cheap pressure gauges have gone in the trash due to pressure killing them.

1idejim · #5 10-24-2010, 12:18 PM

Quote:

Originally Posted by DanaMac

A lot of the newer meters have a plastic/PVC style bottom. We can typically see static pressure between 100 and 150 psi without a PRV. A couple cheap pressure gauges have gone in the trash due to pressure killing them.

you are right about the bottom but i think that's for repair access.

buy better gauges.

DanaMac · #6 10-24-2010, 12:32 PM

Quote:

Originally Posted by 1idejim

buy better gauges.

I have since.

mitchgo · #7 10-24-2010, 02:27 PM

I've yet to see physical damage. However I see the annoyance it causes home owners all the time. The noises inside their house can really drive someone nuts!

Kiril,

What would cause water hammer inside a house when a zone is being opened, but not closed?

txirrigation · #8 10-24-2010, 02:31 PM

Wish I took pictures of my last one. 4" pipe that ran 350 yards at 115 dyn. pressure. Went into a 90 deg then was reduced (at the 90) to 1 1/4. The 90 was cemented in by the installer, and when it blew it made a 20yd. trench and the 40-50lb cement block was 15yds away.

2700 dollars later it was fixed with a pressure reg, and properly stepping down the pipe.

I would complain about the installer, but he keeps me in business with his crappy work and he is one of the biggest comm. installers in the area.

Wet_Boots · #9 10-24-2010, 02:45 PM

Quote:

Originally Posted by mitchgo

What would cause water hammer inside a house when a zone is being opened, but not closed?

It isn't hammer, despite the banging noises and the thumping pipes. It is more like an oscillation. The initial rush of water into the zone creates lowered pressure upstream of the valve. Undersized supply lines contribute to the phenomenon.