how much suction

dmunneke

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How much suction does a jabsco diaphram belt pump generate before it primes.. Will it suck up small portions of water without getting fully primed ?
 
According to Jabsco's propaganda sheet, it will self-prime a little over seven feet vertically. That of course, is if it is in tip-top shape.

If there is some residual water in the lines, it will draw that out before you get a smooth flow of water. But what I'm getting from the way you worded you question is that you aren't getting a smooth flow at all, and that it's spitting and sputtering. If it's doing that, you've likely got a bum diaphragm in it.
 
Thanks Vic, I dont own the pump, what I'm trying to do is duplicate the "arid bilge" system. They use a vacum of some sort to a porous type pickup that gets that last little bit of water out of the bottom of the bilge. I'm trying to discover what a proper pump for this purpose will be.. I thought about a diaphram pump. They do the verticle pull but I need actual suction not just a gentle tug. Just wondering if this would work in a capacity that there is never enough water do getreally going but could still create enough suction to suck up that little bit through a custom pickup of my design.
 
Sorry, I have no idea how to measure the suction, short of somehow attaching a vacuum gauge to the pump, and what that reading should be...
 
Unless the pump can handle a WHOLE LOT of air (such as a shop vac) once you start getting air into the line from the suction, air being lighter than water will go up the suction hose faster than the water, and while the bilge might get dry, the moment you shut off the pump any water left in the line will drain back into the bilge.

The only solution I know for this is a SMALL suction line, say 1/4" ID that doesn't allow the air/water mix to separate (kinda like getting that last bit of pop with a soda straw). It won't do much for volume but it will get the water out. A diaphragm pump should be able to do it if so fitted.

Sucking water through several feet of 1/4" hose will put a load on the pump and draw a lot of amps. You can reduce this load by drilling a SMALL hole in the suction line a couple inches above the pickup. This will introduce a little air into the water; and it'll be easier to pump.

How you're gonna operate this critter is gonna be another challenge; a float switch obviously won't work. Maybe some sort of timer?
 
I think a timer is the answer or a contact water switch of some sort. I think a timer is easier..
 
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