Water pump discharge line 1

[alienitmeca]

Hello,

In a fire fighting project that I, and my coworkers are designing, we seem to have a bit of probleme at the discharge line of a water pump (Q= 1115 m3/h, P= 15 bars). As matter of fact, we had an elbow (LR) at the discharge nozzle, but when we rechecked on site restrains, we had to replace it with an other elbow (SR). My question is as follows:

- Is it acceptable to use a SR elbow at the discharge line of such pumps? if not could you explain why ?

- If it is not accpetable, could you please provide another solution

looking forward to recieving your responses

 

[EdStainless]

How much will this run? Do you really care if you are damaging the pump? Have you considered the loads involved?
And elbow at the discharge will cause off-center loads on the impeller, shaft, bearings, and seals.
There is no orientation that would allow a straight run out of the pump? not even upward?

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P.E. Metallurgy, Plymouth Tube

 

[LittleInch]

It's not a great idea as Ed says but for an occasional use then is acceptable. The swirl and forces on the nozzle will be fairly intense, but not critical to the operation.

That's quite a large flow. I'm surprised you've had to squeeze this important pump into a small space but we have no information to use.

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

 

[alienitmeca]

It is a water pump used in case of fire, but according to the contract, it must be able to run for 12 hours,

what I understood from your replies, is that the real problem lies in a piping stress calculation, not a pressure drop, please correct me if i am wrong

 

[Artisi]

Is it possible to reposition the pump?

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.)

 

[LittleInch]

Stress on the pipe and erosion of the inside if you run it for a long period (months).

It also might impose issues back on the pump - they normally like at least 1 or 2 D straight pipe, but check the installation manual of the pump supplier to see what they recommend. Also talk to them about your situation to make sure it won't have serious consequences. they won't like it, but should say it's acceptable or not.

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

 

[alienitmeca]

Artisi, thank you for your reply, in this case, repositioning the pump is out of question

LittleInche, thank you for your reply, I think that's what I should do, and I will be checking the installation manual, apart from the manual, is there any Standard or handbook that could help, I am trying to get the best out of this probleme, still learning you know

 

[LittleInch]

see this thread

http://www.eng-tips.com/viewthread.cfm?qid=408292

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

 

[bimr]

see this thread:

http://www.eng-tips.com/viewthread.cfm?qid=406497

 

[EdStainless]

Rotate the pump to discharge upward, if that will give you more clearance.


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P.E. Metallurgy, Plymouth Tube

 

[DubMac]

The SR elbow will not hurt a thing in your fire service. Thousands of chilled water pumps operate in cramped mechanical rooms with 90 degree elbows bolted directly to the discharge flange of the pump without problems.

Especially for what is really an intermittent service, you will have no issue with pipe erosion either.

 

[Artisi]

Not an ideal situation but agree with DubMac, so long as the SR elbow is correctly sized.

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.)

 

[alienitmeca]

Thank all for your informative replies, I think will go for the SR elbow solution, since changing the pump discharge to upward position is out of the question at this stage of the project.

Thank you everyone