Check Valve or Ball Valve

[mas985]

I believe most pump manufactures recommend at least 5 to 10 times the pipe diameter but I believe that rule of thumb is a hold over from the water distribution industry where the inlet pipe was fed directly into the impeller inlet. This helped keep a uniform and balanced load in the impeller. A pump with a basket changes the dynamics quite a bit so I really don't think it is as important because the pump basket tends to smooth things out a bit.

 

[jblizzle]

That is interesting ... I recall seeing very few pads that have 10"-20" of pipe in front of the pump before the 90 coming from the ground. Seems like some are lucky if any pipe is exposed before the pump at all

 

[Diver]

Do you have a picture of them or a web reference?

here it the pic. don't mind the mess - i redid the pipework after that

 

[mas985]

They look to be similar to a knife gate valve and without knowing exactly how it is designed, I am only speculating but they should be fairly low head loss.

 

[carlscan26]

So from other posts on this board I was under the impression that a check valve on the suction side of a pump can create a suction hazard. Is this the case or not?

 

[Bama Rambler]

It is the case. Here's the reasoning.

Something blocks the suction in the pool and normally the svrs system on the pump basket or built into the pump will relieve the suction by allowing air in or shutting off the pump, but if you have a check valve it will close as soon as the svrs opens or the pump shuts down, holding the suction in the piping and therefore holding the entraped object to the suction line.

To overcome this you have to install the svrs device between the check valve and the pool. Also, svrs rated pumps won't work in this situation.