On Wed, 26 Apr 2006 21:38:24 +0100, David Billington wrote:
I can't remember the specific equations now that show when water hammer
will occur but water hammer is caused when the valve controlling flow is
shut down too rapidly causing a pressure pulse in the system. Is there
any way to slow the closure of the control valve.

It can also happen when opening a valve too rapidly. Think pulse-jet,
it's probably the same mechanism. But the fix is to, as someone else
said, puta vertical air-filled column to the pipe in question, to
absorb the impulses and smooth them out so they can damp down to zero.

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.