Plumbing booster pump
Plumbing booster pump
(OP)
The toilets in a new building are not flushing correctly. It is being blamed on the size of the pump.
The booster pump which has a duty and standby pump rated at 114' head and 45 gpm each and a jockey pump rated at 114' head and 22 gpm in the basement ( elev 35' ) has 60 psig and they are only getting 10 psig at the third floor ( elev 85") . This is a large building and I cannot guess at the loss in the piping. This is a greywater system so there is no initial head prior to the pump.
This building has a new "green" toiulet flushing system which flushes lightly for liquid waste and heavy for solid waste depending upon if the handle is pulled up or down.
Do these numbers seem odd???
Thanks for any response.





RE: Plumbing booster pump
Easy way to answer is go there at night, use the facilities, flush and see how they work then. If they work fine at night, you've most likely got a pump capacity or pressure problem. Then see how many you can flush at the same time before the problem comes up.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Plumbing booster pump
is 114ft the design operation point for the pumps when running at full demand?
is 60psi the non operating pressure in the system (no toilets flushing)?
is the 10psi (3rd floor) the non operating pressure or the pressure available with toilets flushing?
what is the elevation of the pumps relative to the basement and 3rd floor?
Why aren't they flushing correctly?
RE: Plumbing booster pump
is 114ft the design operation point for the pumps when running at full demand? YES
is 60psi the non operating pressure in the system (no toilets flushing)? YES
is the 10psi (3rd floor) the non operating pressure or the pressure available with toilets flushing? DO not know
what is the elevation of the pumps relative to the basement and 3rd floor? Pumps are in the basement
Why aren't they flushing correctly? Manufacturer indicates it needs 30 psi at the valve to operate the toilet
It is weird that the toilets will operate better with conseqtive flushes.
RE: Plumbing booster pump
That is the relevance of the basement (elev 35ft), don't understand where this fits into the discussion..
Posting a sketch of the system with levels etc might make thing a bit clearer.
RE: Plumbing booster pump
Don't forget to post the pump curve.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Plumbing booster pump
If I understand correctly, you have 60 psig static (no flow) and your pumps operate at a boost of ~50 psi at 45 gpm for each of the first two pumps and 22 gpm for the third pump. Although you also say they are only getting 10 psi at the third floor which is about what you would get if you had no static pressure coming into the pump. The flush valves on the third floor will be ~53 feet above the pump elevation. From my rough calc's you should have ~110 psig of pressure available when you flush.
There seems to be something wrong with the numbers or how I understand what is being conveyed. Typically, water pressure to plumbing fixtures is limited to <80 psig. You seem to have more than that.
Also, was it determined that the system was flushed properly. Are all valves open all the way? Was the pump that was designed the pump that was installed?
RE: Plumbing booster pump
Two pumps 114' head 45 gpm, jockey pump 114' head 22 gpm.
50 feet from pump to 3rd floor. Guage on pump reads 60 psi.
RE: Plumbing booster pump
50psi at the pumps when operating, pressure at the 3rd floor can only be 28psi at best without considering friction and other losses.
You need to involve the system designer - unless of course it's yourself.
RE: Plumbing booster pump
Some more information.
The system has a stop cushion tank with a 90 gallon capacity.
If the jockey pump is not running should the stop cushion tank immediately augment the system.
RE: Plumbing booster pump
RE: Plumbing booster pump
Several people have told me that the tie in for the stop cushion tank should be to the pump set discharge header. It currently ties in on the discharge side of the jockey pump before the Cla-Valve. I have attached a photo for refernce.
RE: Plumbing booster pump
RE: Plumbing booster pump
As a continuation of my pumping problem I ask tyhe following question. When a pump is required to produce 60 psi for a grey water flushing system (2-3psi suctionside)is this pressure and flow expected to be constant when one toilet flushes?
The cushion tank has been filled but the poor flushing continues. Can gpm be tied into the problem.
RE: Plumbing booster pump
The manufacturer of the pump set call for the cla-vavlves to be set with 25-35gpm of flowing water. What impact would this have on the system pressure.
RE: Plumbing booster pump
What type of facility do you have?
It seems the pump and equipment are ok. It sounds like something in the piping system.
RE: Plumbing booster pump
Shut off head point = 138' (60psi)
BEP Flow head = 114'
The flowing head at the third floor is 23' (10psi)
No flow head AT the third floor elevation (85') which is 50' above the pumps (elevation 35') = 88'
That is 138' - 50' = 88'
That leaves a head loss of 65' (or 28psi) when the water is flowing.
(88-23)
The head loss can be only friction head or velocity head as the problem with the accumulator tank has been addressed. Assuming a 2" pipe and a flow of 35gpm the velocity head is only 0.4 ft so we can ignore velocity head.
That leaves only friction head. It would appear that you need to find out why you have such a high friction head.
It could be because
1) the pipe length is too long or
2) something is obstructing the pipe diameter such as a crushed pipe or something stuck in the pipe somewhere.
I suggest you fit a pressure gauge at several locations along the pipework and find out if your pressure drop is gradual along the piping or is concentrated at one point.
Good luck
Ron Frend
http://www.predicon.net
RE: Plumbing booster pump
lfg2007 - have you discussed this with the system designer? Seems like a logical move, a least you will have the background to the initial thinking and a starting point on which to base the trouble shooting, at the moment you are snatching at straws looking for an answer and not working your way thru' it in a structure manner.