You are referring to an "anti siphon valve" or sometimes called a "snifter"
valve. These valves are reliable. but rely on pressure to seal, if the
pressure is low, the seal is not tight - with the potential for a "drip". I
also don't see the need for absolute perfection in the seal?

Mick
"BruceM" wrote in message
...
Don't know what I'm talking about here but I once saw a diagram where you
create a "loop" in your discharge hose so that it is above the water line.
At the top of the loop you have a "fitting" that allows air to enter if
there is a vacuum in the hose but seals when there is pressure in the
hose.
Someone else here must know what I'm referring to? Would this do the job?
BruceM


"Graham W" wrote in message
...

"Karl Timmermann" wrote in message
...
Hello,

I am trying to finish my electric bilge pump for my kayak. [...]

2.) A 3/4 inch or 1 1/8 inch 12 volt electric water pump (about
800-1000
gallons per hour) that needs to be pretty light.

That amounts to 2 pints (a quart) a second! Are you sure your
hand pump can do that? Sounds a bit much to this land-lubber.


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