Manifold for pumps

[Dave K]

Looking for some help on a few Q's,

1. Is it ok to cut the threaded inlet on each pump to shorten?
2. To prevent an air lock, does the pump inlets HAVE to be as high or higher than the top of the elbow which is in between the htru hull and shut off. Can the manifold for the pumps be lower than the gate valve/elbow? ( I was thinkng of a plastic block to raise pumps if need be?
3. Should I use a teflon tape on all threaded joints or use some 3M 4000 on the threads.
4. 3M 4000 wouldnt break down plastic on fittings?

Depending on room which I am not sure about yet I may have to re-configure manifold abit

Thanks guys

[rushin]

Hey, what size are those pumps?

[Dave K]

Hey, what size are those pumps?

Those are 800's. I am using a rule for the front sacs.

[bigdaddy_houseboater]

Looking for some help on a few Q's,

1. Is it ok to cut the threaded inlet on each pump to shorten?
2. To prevent an air lock, does the pump inlets HAVE to be as high or higher than the top of the elbow which is in between the htru hull and shut off. Can the manifold for the pumps be lower than the gate valve/elbow? ( I was thinkng of a plastic block to raise pumps if need be?
3. Should I use a teflon tape on all threaded joints or use some 3M 4000 on the threads.
4. 3M 4000 wouldnt break down plastic on fittings?

Depending on room which I am not sure about yet I may have to re-configure manifold abit

Thanks guys

I like tape instead of dope on plastic. Dope is fine on the brass. The inlet should be lower than the outlet on a centrigul pump, unless you have the suction side flooded. Then it wont matter, but it looks like you got that covered. "Flooded Suction" means that the lake water level on the side of your boat is higher than both the suction and discharge of the pump.
And that's not a gate valve... it's a 1/4 turn ball valve. It's the correct valve to use. Yes you can cut the threaded section of the inlet. It's not pipe thread.. it's straight thread.

[Dave K]

I like tape instead of dope on plastic. Dope is fine on the brass. The inlet should be lower than the outlet on a centrigul pump, unless you have the suction side flooded. Then it wont matter, but it looks like you got that covered. "Flooded Suction" means that the lake water level on the side of your boat is higher than both the suction and discharge of the pump.
And that's not a gate valve... it's a 1/4 turn ball valve. It's the correct valve to use. Yes you can cut the threaded section of the inlet. It's not pipe thread.. it's straight thread.

Both the elbow and the pumps will be below water level and for sure I will keep the pumps above that elbow.

[bigdaddy_houseboater]

Both the elbow and the pumps will be below water level and for sure I will keep the pumps above that elbow.

You should be fine, but I'd endeavor to mount the discharge above the suction a little to let any entrapped air go out with the discharge.

[bigdaddy_houseboater]

Dont forget check valves on the discharge of the pumps.

[rob-dude]

I would build your manifold with non-threaded PVC tees that use PVC solvent - not threaded fittings. This will be less prone to leaking.

[Dave K]

Dont forget check valves on the discharge of the pumps.

Yes. I was going to put them about 2 or 3 feet from the pumps

[Dave K]

I would build your manifold with non-threaded PVC tees that use PVC solvent - not threaded fittings. This will be less prone to leaking.

DAMN what a good idea never thought about it. I was thinking besides fitting everything in the space I have to be careful that I have room to screw and twist things together. hmmm... maybe a quick trip to Home Depot