Question about connection pipe to pump suction

[siva9]

Dear all,

can anyone please help me on the following?

I have to connect a pump with 2 1/2" suction size to an oil tank with an outlet pipe of 1" size.what will be effect of this connection on the total system in terms of pump performance, pressure, oil flow or any other problems. as per the hydraulic manual, the suction pipe should be one size larger or equal to the pump suction size.

Thanks in advance,
regards,
siva.

 

[MJCronin]

siva...

What is your pumped media (fuel oil, gasoline or what) ?

What is the design flow rate and head of the pump ?

Perhaps you should consider the installation of an additional larger nozzle on the tank ?

Without a larger suction nozzle on the tank, you risk "starving" the pump, cavitation and possible loss of the pump itself.

If he refuses to consider reasonable tank modifications, make sure that your MBA boss is standing next to the pump during start-up.....

-MJC

 

[BigInch]

The smaller pipe diameter will tend to reduce suction pressure to the pump, so NPSHA will be affected. It also increases velocity, so that's a very slight good point. Use 2-1/2" pipe and fittings wherever possible, but otherwise just check the NPSHA. If that's OK, chances are you're good.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[siva9]

MJCronin,

Thank you very much for the immediate response. the pumped media is transformer oil.I donot think the head is a problem - the tank height(suction head) is 4m and our pump sits on the same plinth next to the tank. We cannot do any modifications to the tank we have to use the existing 1" pipe on the tank to connect our pump having 2 1/2" suction.thats why i would like to know the effects of this connection.
Please tell me what is this MBA boss.
I would like to know the best possible pipe connection without loosing much of pump performance and any further problems.

can you please tell me where do i need to connect the check valve on the discharge side - immediately next to the pump discharge flange or after the elbow? the pump is a centrifugal pump with axial suction and radial delivery on top.

Thanks in advance,
Best regards,
siva.

 

[siva9]

BigInch,

Thank you very much for the response and web link. can you please tell me where do i need to use the expander from 1" to 2 1/2" - tank or pump?

Thanks in advance,
Best regards,
siva.

 

[BigInch]

He thinks your boss has a Masters in Business Administration and knows nothing about the reality of engineering.

Just check NPSHA, if it shows OK, its not starving the pump.
put the check after the pump discharge flange if you can, otherwise just put it as close to the pump as you can. Correct direction and orientation, either horizontal, vertical up, etc. is more important than exactly where you have to put it. The truth is anywhere in the discharge line will work hydraulically speaking. Closer to the pump may have more advantages if you need to do maintenance on th pump, as would including a backup ball valve to assure positive shutoff if the pump needs to be disconnected from the discharge line. A check valve by itself should never be assumed to be completely closed, especially when it is open for maintenance.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[siva9]

Hi BigInch,

Thank you very much for the immediate response and help.

I am an electrical engineer knowing little about pumps and pipe connection. can you please send me details how to select a pump for a closed system. My application is to pump the transformer oil from tank to heatexchangers and back to tank. the oil flow rates will be 10to 15 l/s.

Thanks in advance,
Best regards,
siva

 

[BigInch]

Maybe you can find what you're looking for here,

http://www.bellgossett.com/Press/BG-cooltowr.asp

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain