Quick Closing Valves and Water Hammer 3

[PEDARRIN2]

The Ohio version IPC in 604.9 states that where quick closing valves are utilized - a water hammer arrestor shall be installed.

My question is what is considered a quick closing valve.

I have always considered a solenoid valve or similar to be quick closing.

I don't consider diaphragm type flush valves to be quick closing. But I am always getting questioned about this.

I want to hear what others think.

 

[alimhmd]

Why you don't consider diaphragm type flush valves to be quick closing.I consider flush valve is the major quick closing valve,and i cosider ball valve quick closing valve.
the quick closing is relation with time,that mean any valve take small time to close is quick response.
i put water hammer arrestor when there are flush valves in the system.
and i also want to hear what others think.

 

[PEDARRIN2]

If I considered all ball valves to be quick closing, I would be providing water hammer arrestors on all my branches that have a ball valve for a shut off valve.

To me a quick closing valve would be a solenoid valve or the older piston type flush valves. A diaphragm flush valve opens and closes a bit slower than that.

I look at the flow that is going through the piping and the velocity.

I design the piping in the chase to a bank of fixtures to be uniform size - no downsizing to the last fixture. That keeps the velocity down when a flush valve is opened/closed.

An issue with water hammer arrestors is they leak over time and need constant maintenance. Thus they need an access panel. Most architects don't like that and a lot of owners don't want to mess with them.

I do consider water hammer arrestors if my bank of fixtures is long or I have a lot of water pressure - but generally, using the uniform size in the chase has worked.

 

[rconner]

fyi see web page at

http://www.terrylove.com/waterhammer_conley.htm

 

[hydrae]

Any valve that can be closed withing 10 cycles of the natural frequency of the system can be considered quick closing.

A back of the napkin calculation of the natural frequency is the the longest length of pipe in feet divide by 4000 ft/sec, you get the longest natural frequency of the system.

So if the system is small, say 40 ft inside a house then a ball valve should be OK as long as nobody snaps it closed, since it should take longer than 1/10th of a second to close the valve. But take a system 10 miles long and even the laziest operator of a gate valve is too fast.

This calculation is quick and dirty, and does not account for things such as pipe material, amplitude addition (which can happen with branch lines) or changes in line size. These cases will require detailed evaluation.

Hydrae

 

[cdxx139]

I consider quick closing valve, as a quarter turn ball valve. Ones that can close in 90 degrees of turning


knowledge is power