Subject: washing machine anti-knock pipe layout

From: adrianw@cassius (Adrian Whichello)
Date: Fri, 27 Jan 1995 00:03:55 GMT

Dear All

a year or two ago (that long!) there was discussion here about a vertical pipe
arrangement that could be used to remove the knock from washing machine
solenoid valves. I recall it was a pipe with a trapped air column at the top. 
The plumber has never heard of it. As we are about to redo the laundry, could
someone tell me the dimensions required, so I can see if it is feasible to have
them installed. Thanks,

Adrian Whichello                            Phone:  +61 2 351 4824
Imaging Science and Engineering Laboratory   Home:  +61 47 588 319 
Electrical Engineering, Sydney University     Fax:  +61 2 351 3847
Australia                                   Email: [email-masked]

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From: [email-masked] (Mike Rehmus)
Date: 27 Jan 1995 17:16:46 GMT

>Australia                                   Email: [email-masked]

In the U.S.A., the device you describe is to prevent "water hammer" and 
is usually just a capped at the top, vertical piece of pipe connected to 
the water pipe to be protected.

Since the water posesses momentum, it attempts to continue its motion, 
causing the hammering sound.  This can actually damage the pipes.

The air trapped in the pipe will compress whenever the water, moving at 
high velocity in the main pipe, is turned off and in this way, cushions 
the hammer.

The length of pipe normally used is from 1 to two feet, as I remember.

Best,
Mike