Qyadruplex Pump Station

[llamallama]

Hello,

My experience is civil/site with some wastewater background. The company I'm working for needs to expand its wastewater effluent pump station. The current system is a duplex submersible going to approx 1 mile of 6" force main. With increased flows it appears they will need to add additional pump capacity. They are not considering upsizing the force main. Based on my latest check, if we add 2 additional pumps, we should be able to handle the additional flow. My question is, since I have only ever designed duplex systems, are there any considerations beyond just adding the pumps in parallel?

 

[bimr]

There are many consideratinos; design pressure of the force main, velocity in the force main, permitting requirements, condition assessment of the useful life of the existing facilities, etc.

 

[micalbrch]

If you add two additional pumps but keep the existing main line pipe size, the head (pressure) will increase. Can your pumps handle that (especially the existing ones)? If you do not get sufficient answers here, I'll recommend the Pump Engineering Forum. There are some real centrifugal pump experts. But wait another day or two to avoid unnecessary double posting.

 

[dicksewerrat]

Are these existing pumps running continuosly? What is the operating pressure in the main? Age of same? What is the outfall of the force main?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[sjohns4]

Aside from the concerns about increased force main pressure, make sure you have the right combination of pumps...such as should you have pumps piped in series or parallel. If most of your TDH is from the static head, usually parallel pumping will show a significant increase in flow. If most of your TDH is from friction loss you'll have to have pumps in series to see a significant gain.

Some general suggustions:

Just as with a duplex, consult the pump manufacturer for pump spacing dimensions, then add some extra space incase someone swaps in a different pump down the road. Talk to a panel shop about the controls...you'll probably want them to come on sequentally with water level and have the order automatically alternate so the lead pump doesnt get worn out, and you're not kicking all the pumps on when only one or two would do the job.

Could you get by with two larger pumps than four smaller ones? I tend to like more smaller pumps but if you're limited on existing wet well space or larger pumps just arent that "big" that may be something to consider.

Mike

 

[gerhardl]

Pumps and pipes in parallell joining a common main need considerations in layout and also additional thoughts for size and types of check valves. Wrongly selected and put together uneven performance of the different strings could be the results and give problems, one string getting a too low flow compared to others, giving check-valve gulping in this stream and overwork of the others pumps.

Although lacking experience for pumps, two pumps in series sounds better for this case, but correct solutions will have eqal long lifetime for the other.

As above: good pump companies will give you a suggested solution with types and preliminary price. As always also ask if they have suggestions on how to prolong life expectancy and service intervals and performance with additional or better solutions than their 'cheapest' solution.

Price/lifetime calculations could surprice you.