Identify clothes washer part?

[DaveC]

Yes it does, when mains pressure drops to zero two things are possible
without the air brake:

1. Mains pressure actually turns negative (very common, just takes one
opening downstream to do this...)

OK, the mechanism for contamination exists.

2. Even if pressure is truely zero, contamination will backflow into
the pipe, and at a surprising rate. Technically it is possible even
with full pressure (this is caused by boundary layer effect where the
water at the side of the pipe or conduit is not moving.) A pipe run
underwater, with a pin hole, will draw contamination into the water
supply. If that 'underwater' water source is heavily contaminated, the
amount of contamination can be significant.

BUT THERE'S **NO** "DIRTY" WATER IN CONTACT WITH THE FILL HOSE!! THE WATER IS
10" BELOW THE HOSE!! HOW IS THE WATER SUPPOSED TO EVEN MAKE THE TRIP UP TO
THE HOSE AND THEN TO THE MIX VALVE, ANTIGRAVITY?!
--
DaveC
me@bogusdomain.net
This is an invalid return address
Please reply in the news group

 

[Dave Platt]

BUT THERE'S **NO** "DIRTY" WATER IN CONTACT WITH THE FILL HOSE!! THE WATER IS
10" BELOW THE HOSE!! HOW IS THE WATER SUPPOSED TO EVEN MAKE THE TRIP UP TO
THE HOSE AND THEN TO THE MIX VALVE, ANTIGRAVITY?!

Granted that this can't occur during normal operation. But... is it
physically possible, at all, under *any* sort of fault condition, for
the dirty water to rise up as high as the opening of the fill hose?
Say, if the fill-level sensor happened to malfunction, and the
controller left the fill/mix valve open for so long that the washer
filled up to the very top of the barrel and began slopping over on the
floor... would this be high enough to allow back-suction?

My guess is that the codes are written in such a way as to require a
vacuum-breaker failsafe unless it's physically impossible for backflow
to occur, even under extremely improbable multiple-fault conditions.

A washer manufacturer might have only two alternatives to comply with
the law: either go through a bothersome, well-documented physical
analysis process to demonstrate that a vacuum breaker wasn't ever
going to be needed, or just go ahead and install one. By doing the
latter they'd eliminate any possible conflict with some jurisdiction,
somewhere, which has a code that absolutely requires a vacuum breaker
on any clothes washer.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[John E.]

A washer manufacturer might have only two alternatives to comply with
the law: either go through a bothersome, well-documented physical
analysis process to demonstrate that a vacuum breaker wasn't ever
going to be needed, or just go ahead and install one. By doing the
latter they'd eliminate any possible conflict with some jurisdiction,
somewhere, which has a code that absolutely requires a vacuum breaker
on any clothes washer.

A thorough, practical analysis of why there's a vacuum break on every washer,
whether needed -- or not, and whether it serves a real purpose (other than
employing repair personnel when it leaks) -- or not.

Thanks!
--
John English

 

[PeterD]

On Wed, 8 Jul 2009 09:38:39 -0700, DaveC <me@bogusdomain.net> wrote:

Yes it does, when mains pressure drops to zero two things are possible
without the air brake:

1. Mains pressure actually turns negative (very common, just takes one
opening downstream to do this...)

OK, the mechanism for contamination exists.

2. Even if pressure is truely zero, contamination will backflow into
the pipe, and at a surprising rate. Technically it is possible even
with full pressure (this is caused by boundary layer effect where the
water at the side of the pipe or conduit is not moving.) A pipe run
underwater, with a pin hole, will draw contamination into the water
supply. If that 'underwater' water source is heavily contaminated, the
amount of contamination can be significant.

BUT THERE'S **NO** "DIRTY" WATER IN CONTACT WITH THE FILL HOSE!!

In the event of malfunction, there easily could be. So they must plan
ahead for that possibility.

THE WATER IS
10" BELOW THE HOSE!! HOW IS THE WATER SUPPOSED TO EVEN MAKE THE TRIP UP TO
THE HOSE AND THEN TO THE MIX VALVE, ANTIGRAVITY?!

Your keyboard keycaps key is stuck, you should check on that.