[C320-list] antisiphon valves

[Steve Magennis]

The anti-syphon valves work like the joker valve in your head, that is,
they have a "duck bill" that points into the valve, and it is seated
with the screw cap (which has a hole in the end.

The way the valve works is when there is water under pressure in the
hose, the pressure presses the lips of the duck bill together and
prevents leakage.  Once the water pressure is removed (you are no
longer pumping water through the hose), the "lips" can separate and
allow air back into the hose.  This will break any vacuum (as long as
the lips are still flexible).

This is why you don't place an anti-syphon valve in the water supply
line from the through-hull to your head pump (this line is under
suction, not pressure, when you pump the head) but must place one
between the pump and the bowel (this is the pressure side of the pump).

Steve
Alchemist #909

--- harold brown <jbrown5093 at yahoo.com> wrote:

> Thank for the information. Mine are now screwed down
> tight they were all open (including the one for the
> engine). Funny the owner's manual maken no mention of
> it. What is the purpose of having the vented valve in
> the first place? Jim Brown
> --- Quentin Murphy <qmurphy at sympatico.ca> wrote:
> 
> > These should be screwed tight.  Some 320s also have
> > another anti-siphon
> > valve (engine) in the main cockpit locker.  Mine
> > loosened last year and
> > caused the aft cabin berth (including the bedding)
> > to get a good soaking.
> > It took months to get the space under the locker dry
> > and every time the boat
> > heeled, it re-wetted the berth.  Not too pleasant!
> > 
> > Quentin Murphy
> > Celtic Knot #667
> > 
> > -----Original Message-----
> > From: c320-list-bounces at catalina320.com
> > [mailto:c320-list-bounces at catalina320.com]On Behalf
> > Of harold brown
> > Sent: July 4, 2007 3:45 PM
> > To: c320-list at catalina320.com
> > Subject: [C320-list] antisiphon valves
> > 
> > 
> > Probably a dumb question but are the screw down caps
> > on the 2 antisiphon valves in the head cabinet
> > supposed to be screwed down or left partially open?
> > Jim Brown     Desafinado
> > 
> > 
> > 
> >
>
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> 
> 
>  
>
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