Check Valve Location in Drainage Sump?

What does the pump vendor say in the Installation Manual ?

Does it mean, we should always go by pump vendor recommendation even there is no valid or well established technical reason. If pump manufacturer or for that matter any manufacturer will be asked, they will reply what best option possible and that is nears by pump and that is also typically general industrial practice.

Here question is, does it will effect so much that check valve never be installed above vertical to far away from pump ?

Install the valve approx. 10 diameters above the pump. Drill a 1/16" weep hole in the discharge pipe just above the pump. This does two things; reduces the static head hold on the valve by raisng it towards the top of the water column and gives the pump a running start to send a water slug at the valve to open it smartly.

Why this 10 m ( Assuming this is round figure of 9.81) above pump is the criteria.

if upto 10 m from pump check valve installation can be recomended then why not at 25 m ? Let us be theoretical what will happen ?

Far away, he no check! Don't put it in at all and save some $. Close, he work good.

Capiche?

Not meters, DIAMETERS!

I have installed the check valve up above the sump pit for maintenance reason with no adverse effects. I do drill a small hole in the line in the pit to reduce strain on the motor on long risers. Most of the water hammer will be the valve closing as the pump stops. The amount will depend on how much head pressure there is. That can be address with the type of check valve used.

Not being there you have to take in consideration the amount of water in the line. If there is sufficient water there to drain back down and start a cycle of the pump. I have a sump here on a piece of equipment that the riser holds more water then the pit. The check valve is out of the pit about 4 feet above floor level. When the valve fails not only does it flood the motor starts up a reversed rotation. Water running down the riser already has it spinning in that direction.

25 m seems a lot of head for a drainage pump. I presume to service the pump, you would have to pull the 25 m of pipe with the pump. There are going to be joints. Empty pipe would be lighter and less messy when un-doing the joints.

I would want a manual valve, a flanged horizontal check, and a gantry or something to put a pulley system on for pulling the pipe and pump.

hi

check valves are used for several purposes the main one is to stop the pump running backwards after stopping in case you have auto level starting and the controls re-starts the pump while its spinning backwards, that action WILL break a shaft or coupling. The other reason is to keep the fluid you've pumped in the discharge tubing and to stop back flow reducing the time taken to lift the fluid to surface.

In the oil industry and with ESP's, which is my speciality, CV's (Check valves) are installed close to the discharge head, with a bleeder valve above (this lets the fluid out of the tubing before pulling the ESP and tubing)

If i read your post correctly you have a pit 25m deep I guess that you can recover the pump on its own and the tubing is fixed so the pump sits on a flange with a gasket, (??), having to pull the tubing to get at the pump might be difficult, but not impossible and if you do then you can complete any maintenance on the CV if installed.

Placing the CV OUTSIDE the pit is not a good idea because of the back spin and the auto-start (on fluid level?) due to the amount of fluid flowing back to the pit.

air locks and hammering not a real issue at that depth. I suggest that you ensure that the fluid level is high so the pump is always in fluid, if not already.

what sort of fluid are you pumping.. rain water. dirty water, does the fluid have solids that could/can stick open a CV... do you really need a CV?

If you don't really need a CV because you feel you can't install it for ease of servicing, etc then I suggest you fit to your auto-start a timer to STOP any restart for at least 15 mins after stopping.

This gives the motor/pump time to stop back spinning and to cool down as repeated cycles (stops & starts) to take their toll on the motor.

So you have two options.. fit a CV and fit is close to the discharge head but make sure at least once a year you can pull it to surface and clean it, or don't fit one and install a delay timer so your auto-start waits for 15 mins (or a delay of your choosing) so you don't break something important.

Nearly forgot.. drilling holes in the tubing NOT a good idea. The pump will be balanced which is what I think the reply was trying to put across... no further hydraulic balancing is required.

I think this is the topic of discussion. Here in this discussion Brich is suggesting not to put check valve out side pit while OZZB having practical experience of putting check valve out side pit and system is operating successfully. So, whether check valve can be installed out side pit ? Obliviously this is not a preferable, but what will happen if check valve installed out side pit of 25 m deep ?

I am participating in this debate and taking OP pump data as 450 m3/hr @ 25 mWC.

Let me assume pumps are also controlled by float type level switch. In this situation if level goes down at specified level ( Minimum submergence recommended by pump manufacturer), pump will stop and if we assume piping system is leak proof then water at check valve level is remain hold because in pit there is still considerable amount of water. Or other wise(if piping below check valve to pump discharge have very little leakage) will come down from check valve level to pit level very slowly which may not cause reverse spinning of pump and after some time pipe will be empty. As Brich is suggesting air log and water hammer is not a major issue then check valve may be recommended to install out side pit even after 25 m.

Speaking as one of those poor fools that used to get left (I'm retired now) change the non-return on XYZ pump on shifts in the middle of the night. Please put it at the top of the sump! Drill the vent or fit a ½" N/R valve to empty the riser, it eases the starting.

As ozzb says don't refill the pit to the point it starts the cycle all over again. Seen it, done it, and got the slap around the face with the wet rag for doing it.