Bilge pump non-return valves

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Graham_Wright

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www.mastaclimba.com
In a word, they are not!

The ducks bill type introduce resistance to forward flow but still allow a gradual run-back. Flapper valves seem to be fouled by the slightest bit of dirt.

Anybody found an effective one?

I wondered if there exists a solenoid valve activated by the same input to the pump;- zero forward resistance and no flow back.
 
<<<< I wondered if there exists a solenoid valve activated by the same input to the pump;- zero forward resistance and no flow back. >>>

They are available, for example here. Corrosion resistance might be a problem. Would the cost be justified?

Not quite sure why this is a problem for you. The worst that can happen with a properly designed system is that a hose-full of water runs back into the bilge. Is that a big problem? I guess it's different if your boat is wooden, but I adopt a zero-tolerance approach for water in my bilge. My manual bilge pump only operates for testing purposes or after playing with raw-water pump and cooling circuit.
 
You could possibly do something with a 12V motorised valve linked to the bilge pump feed.... but it would be a lot of hassle and another thing to go wrong... personally, if it was that much of an issue, i'd think again about the location of the outlet through hull!
 
I have always assumed that the reason for having a non return valve for the bilge pump is to allow quick pump priming, particularly when the pump is mounted a meter or so above the strum box. As I have never been able to stop the non return valve from sicking in a frozen, closed position, this winter I have extended the suction hose and made a large loop in it, doing away with the non return valve. This is on my automatic bilge pump, for when the boat is unattended, but I have a dry boat and the loop hasn't been tested yet.
 
Further information.

The pump is the submerged type in the shower sump.

If I discharge lower down (i.e. below the heeled water line), the boat will sink!

One solution could be to use a Whale gulper higher up (it has a large lift/self priming capacity) but it is relatively slow. Maybe a combination of that and a submerged would do the trick.

The idea of a motorised valve inspires. They are common in central heating zoned systems (and in the scrap yard!) but run off 230v AC. Still, could be way to go.
 
[ QUOTE ]
Not quite sure why this is a problem for you. The worst that can happen with a properly designed system is that a hose-full of water runs back into the bilge. Is that a big problem?

[/ QUOTE ] It could be a problem with a float activated pump and a bilge compartment volume small relative to the capacity of the hose above the non-return valve. Leave the boat with a hose-full of water, water trickles slowly back into bilge, activates float switch and pump, refills hose, and so on until the battery runs flat.
 
[ QUOTE ]
[ QUOTE ]
Not quite sure why this is a problem for you. The worst that can happen with a properly designed system is that a hose-full of water runs back into the bilge. Is that a big problem?

[/ QUOTE ] It could be a problem with a float activated pump and a bilge compartment volume small relative to the capacity of the hose above the non-return valve. Leave the boat with a hose-full of water, water trickles slowly back into bilge, activates float switch and pump, refills hose, and so on until the battery runs flat.

[/ QUOTE ]

But in that case - you should set your switch at suitable level to stop that happening. Unless of course you have an all in one pump / switch - then you're shafted !
 
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