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Syphoning effect on pipework

Syphoning effect on pipework

Syphoning effect on pipework

(OP)
Hi All

We had recently changed our pump (for our effluent system) from a screw pump (BLUE PUMP) to an air operated diaphragm pump. Simple setup.

When we stop the diaphragm pump, the discharge pipe maintain its syphoning effect and still pull the effluent from the suction side (due to the level in Pit 2 and RED PUMP running). We do not want to drain the effluent in Pit 1 to dry.

Most simplest option is to drill a hole (or installed a vent) at X, inside pit 2 but way above the bottom of the first pump discharge.

What's your thought?

RE: Syphoning effect on pipework

Just place a vacuum valve at the top of the loop downstream the blue pump which will stop the syphon.

It's basically nothing more than a spring loaded non return valve.

I don't think your idea would work as its too far away from the peak negative pressure in the syphon

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Syphoning effect on pipework

Vacuum breaker valve at pump level should work but you also need a foot valve at bottom of pump inlet pipe otherwise you may lose pump priming.A small priming tank at pump level may also be needed to take care of leakage thru the foot valve.

Engineers, think what we have done to the environment !https://www.linkedin.com/in/goutam-das-59743b30/

RE: Syphoning effect on pipework

A foot valve or non return valve would help, but given the blue pump is a diaphragm pump it should be self priming, especially if the lift is quite low.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Syphoning effect on pipework

Just cut off some of the inlet pipe so it does not reach below your minimum level mark.

RE: Syphoning effect on pipework

You can also use a full port solenoid valve in the pipe. If the system is automatic, connect the solenoid valve so that it operates when the air pump is operating.

RE: Syphoning effect on pipework

(OP)
Thanks all for the quick feedback.

Will the arrangement below work using a Vacuum breaker?

RE: Syphoning effect on pipework

Quote (1503-44
Just cut off some of the inlet pipe so it does not reach below your minimum level mark.)


Agreed.. pink star for this simple but neat, working solution..

RE: Syphoning effect on pipework

As long as you don't mind getting sewage sprayed on your face as you walk by. You mentioned "effluent system" which indicates that this is a sewage application. Vacuum breakers are not recommended on sewage because of the potential for failure from clogging.

RE: Syphoning effect on pipework

If you cut the pipe the outlet end may be above the downstream tank level (possibility). If it happens the pipe may become empty due to back flow. It is doubtful whether the pump cam pump out air to create vacuum for priming(it is only an assumption).

Engineers, think what we have done to the environment !https://www.linkedin.com/in/goutam-das-59743b30/

RE: Syphoning effect on pipework

Just put a full bore ball valve in the line and wire it so that it opens when the pump is running and closes when the pump stops.

Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

RE: Syphoning effect on pipework

searching for "sewage vacuum valve" seems to show the valve vendors do specific version for waste water. e.g. https://www.valmatic.com/Portals/0/brochures/Air_1... page 6

Now how good they are in practice is another matter, but at least they are simple and need no power.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Syphoning effect on pipework

Cutting off the inlet pipe short will only work if the pipe siphon flow is not high enough to fill the discharge pipe, allowing air back up. If the piping has a sufficient drop between the two levels, that idea may not help at all.

RE: Syphoning effect on pipework

So the water just jumps up into the higher inlet???

RE: Syphoning effect on pipework

Just depends if ER Azza wants flow to stop when the pump stops or just doesn't want pit A to empty.

Of course if you cut the pipe off you will want a second pipe and valves etc to go to the bottom so that if you want to you can pump out the first pit...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Syphoning effect on pipework

Good idea. You could prime it easier too.

RE: Syphoning effect on pipework

1503-44,

My apologies, I misunderstood which pipe you were referring to. I thought your were suggesting that for the piping going from the pump to the second tank, which is technically the inlet feed to the second tank, not the pump suction line.

I'll leave my previous post so the conversation train still makes sense.

RE: Syphoning effect on pipework

No worries.

RE: Syphoning effect on pipework

Bimr said "Vacuum breakers are not recommended for sewage."
I tend to believe what bimr says.

RE: Syphoning effect on pipework

Why would it matter what's in the flow if the breaker is put up above the actual flow with a few feet of pipe?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Syphoning effect on pipework

$hit happens ???

RE: Syphoning effect on pipework

Why not put the vacuum breaker on top of a stand-pipe on the vertical section that drops down into the second tank? The height of the stand pipe can be adjusted to avoid any splashing potential. The stand pipe can be flanged to aid in removal and cleaning in the case of buildup. Locating it on the vertical down section should also mean that gravity will aid in removing any potential clogs. Lastly, if you can accept a small amount of water addition, you can put a trickle flow of water in at the top of the stand-pipe in a weir design to keep the sides of the standpipe constantly wetted, minimizing the buildup potential.

RE: Syphoning effect on pipework

Another solution is a small diameter bleed off. When the pump stops the siphon will break if the end of the pipe is above the liquid in the first tank.

RE: Syphoning effect on pipework

For waste water the small diam bleed is more likely to clog than the vacuum valve IMHO...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Syphoning effect on pipework

(OP)
Hi All

Thanks for all the feedback and advise.

Yes, I finally put an inexpensive vacuum breaker on the line.
There is a high point on the pipe which I managed to install a 1" vacuum breaker.
That did the job.

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