Pumps in parallel Header Size

[ahmedan47]

I have a case of 3 centrifugal pumps connected in parallel .
the pump is 70 m head and 75 cubic meter per hour , the delivery line is 2" so is the main header >
when the pump starts the fluid comes out every valve gasket like a jet . i changed these gaskets many times and the problem remains .
when i deliver to a bypass to the atmosphere ( not in the very long main delivery line ) every thing seems to be fine . i guess the problem is in the design of the header as it can't withstand the pressure of the pump
i would like to know your recommendations about this
thanks alot

 

[LittleInch]

You've identified the problem. Now the answer is to buy equipment rated for the correct pressure.

A 2 inch header looks very small for that flow rate.

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

 

[ahmedan47]

Thanks alot LittleInch
i appreciate your nice reply

 

[Artisi]

It's not a problem of the header, although the header is probably hydraulically undersized, it is simply a problem of the pipework/ valve interface. As pointed out attend to the problem with correct connection and gaskets.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[QualityTime]

75 m3/hr = 302 usgpm...that is like one port on a fire hydrant open...yes, and the water will comes out like a jet when a hose is connected to it...LOL...could not help it
Velocity though 2" pipe = 31 ft/s!!!!!! YIKES!
70 m = 99 psi

Sounds very unusual for water to be leaking through a valve gasket. I am not sure if you are talking about the valve flange gasket or the valve seat gasket. Even a 2" valve that you buy in a local hardware or plumbing store is pretty well rated for 125 - 150 psi.

You don't like to see the velocity anywhere in the piping to be greater than 10 ft/s. You will wear out the valve seats very quickly.

 

[LittleInch]

QT. Can you check your numbers. I get one pump at approx 10 m/ sec. / 35ft/ sec.

What we don't know/ Bachmann asked is what is the inlet pressure into the pump. ....

I think there nigh be a lot of issues worth this unknown system.

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

 

[QualityTime]

Thank you LI. I revised my post....tough to think properly without my contacts on! The water must be ABSOLUTELY SCREAMING through the piping. I hope they have ear muffs for everyone.

I think they have the answer.

 

[LittleInch]

Well it's probably not going that fast as the pumps won't be doing anything like 70 m3 hr, but unless inlet pressure is high I agree the pressure doesn't seem that high.

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