Help with pump design

[Suchbirthday9919]

Young engineer working on pump project. Pump suction/discharge is cleared with air at end of operation. I am looking at installing new pump down a level. I have option of moving automated block valve on suction to lower level or leaving where it is on upper level. It is a PD pump and running dry isn't an issue. I'm not sure how to figure out if it is advisable to move the automated block valve. Seems like it would help get the liquid to pump faster with more head pressure if I do move it but I'm not sure if it will be an issue if I don't move it. Also struggling to figure out how to determine if the air is enough to clear the additional pipe.

 

[LittleInch]

Can you draw a sketch with some dimension so we can figure this out as it is quite hard to understand all these different levels and location of valves and pump.

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[Suchbirthday9919]

I am not in a position to sketch right now, so hopefully me elaborating will fill in the gaps. I'll ignore the floors. Let's say the automated block valve on suction is currently 15 ft above the pump. The change, for example, would leave the automated block valve 30 ft above the pump unless I move down the tie-in. The line downstream of the automated block valve is cleared to the destination tank with air after use regardless of piping change.

 

[georgeverghese]

Why do you clear the pump, suction and discharge with air at end of operation?
And also explain why there is some limit on air supply if automated valve is left where it is now :
" Also struggling to figure out how to determine if the air is enough to clear the additional pipe."

 

[LittleInch]

Also what is inlet pressure? If this valve is at a high point on the pump inlet line and liquid level is lower you won't be able to lift the fluid up over the high point. Hence why we needed a simple sketch.

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

 

[LittleInch]

If your inlet conditions and discharge conditions stay the same then moving the pump further down will have no impact on its performance.

Only if this affects the start up scenario when priming the pump will it be an issue.

If the air is used to clear the inlet and discharge lines then the pressure required will increase when the first section of inlet line to the pump is cleared as you now have to push the discharge line 15ft further up.

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