The only problem is that over time (a variable) the air will be absorbed
into the water nullifying the shock absorber effect. To be long term, the
best solution is to have something that separates the air from the liquid--a
diaphragm or bladder such as found in most accumulators.
MLD
"Jeff Wisnia" wrote in message
...


Pop Rivet wrote:

"Jeff Wisnia" wrote in message
...

OK, here's the one which operates on machine current flow:




http://www.accentshopping.com/store/...alve/A2CM1.asp

But, I'm still wondering what happens if a hose finally

gives up and

blows from the shock created when one of the machine's

solenoid valves

slams shuts at the end of a fill or rinse cycle.
...


I think the operative word here is "shock" created by the
valve closing. If you have a properly designed/installed
plumbing system, there are air "traps" in your pipes. Their
purpose is to absorb shocks such as you describe; air
compresses under increased pressure where water does not.
The momentum and pressure buildup is absorbed by these air
traps rather than bursting pipes and hoses, so that, to your
hoses, it's no different than if hte water were turned off
by hand.
You can add your own air traps if none are present near
the machine by simply adding about a 2 ft length of the same
diameter (or larger if preferred) vertical pipe near the
connection to the hoses.

| Air trap
|
---------- |-------------- Water supply

It must, of course, go up, not down, so that it has air in
it all the time when the water enters the pipes.
One for each water supply. As long as those remain full of
air and don't leak (as in all plumbing), then you're fine.
If you have them but they aren't working, then you may need
to bleed those water lines dry so that air can get back into
the traps.
A good test for how bad the "shock" is, is to use a water
hose and quick-action nozzle (not the twist type).
Momentarily attach one to the faucet and start the water
running, the let go of the handle and let the nozzle turn
the water off quickly: The hose shouldn't jump when the
water "slams" off. In a good system, thjere will be little
motion in the hose. If the traps aren't right, the hose
will give a fairly strong "jump" when you shut the water off
quickly. If it jumps harshly, yuou can probably dupicate
that jump just by shutting off another faucet i the house
quickly by hand - lack of air traps is pretty easy to notice
and often will even be accompanied by a thump or a bang
somewhere along the pipeline. Each faucet in the
house -should- have one of those air traps - they're usually
hidden inside a wall and not necessarily close to the
faucets, so normally one doesn't even know they are there.

Pop



Damn good post, and I wonder what percentage of US homes built in the
last 50 years have those air traps.

Are they required by code anywhere? If not, I'd bet they're mostly
installed at every faucet in architect designed homes for "cost no
option" buyers with rigid monitoring of the as built finished work.

About 30 years ago I was getting "shocks" when the solenoid valves in
our clothes washer slammed shut. I installed a couple of "shock
absorbers" which had spring loaded pistons in them, with the backside of
the pistons open to atmosphere. They were sold for that purpose and
advertised as being resistant to becoming water logged, and could be
mounted at any angle.

Those worked as advertised, but I always wondered how long it would take
before the piston seals would give out and water would start leaking out
their back ends. In my case they were out in the open, so I could spot a
leak if one occurred, but I'm not sure I'd have the guts to seal them up
in a wall.
--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone
to blame it on."