Calculate Total Head
Calculate Total Head
(OP)
This is a very fundamental question which I'm having a tough time explaining to a colleague. Maybe you guys can help.
Question:
What is the total static head in the following piping layout?

To me, the obvious answer is:
Total Static Head = 30m -24m = 6m
regardless of all the bends and fittings etc in the suction or discharge side.
But my colleague insists that as the suction side is not directly to the tank, therefore as a result of all the bends etc (before the pump), the fluid would be at zero velocity and zero potential energy at the suction point. And therefore zero head at the pump, resulting in 30m of Total Static Head.
Can anyone suggest a better way to explain this?
Question:
What is the total static head in the following piping layout?

To me, the obvious answer is:
Total Static Head = 30m -24m = 6m
regardless of all the bends and fittings etc in the suction or discharge side.
But my colleague insists that as the suction side is not directly to the tank, therefore as a result of all the bends etc (before the pump), the fluid would be at zero velocity and zero potential energy at the suction point. And therefore zero head at the pump, resulting in 30m of Total Static Head.
Can anyone suggest a better way to explain this?
---engineering your life---





RE: Calculate Total Head
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Calculate Total Head
Your bud is thinking that head is the result of only v^2/2/g. The total head is z1 + p1/rho + v1^2/2/g - Hl = z2 + p2/rho + v2^2/2/g
BigInch
http://virtualpipeline.spaces.msn.com
RE: Calculate Total Head
---engineering your life---
RE: Calculate Total Head
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Calculate Total Head
When you say "Total Static Head" it's not totally clear what you mean. When I do pump calcs, I would normally have a static head on the suction side AND a static head on the discharge side of the pump. I consider both as I set up the calculation. Neither is 30 m, because you must always reference them to the pump suction nozzle centerline - not to grade as your diagram is implying. However, the difference is 6 meters, which accounts for the static head portion of the work that is done by the pump.
HTH,
Doug
RE: Calculate Total Head
Exactly my thinking. And in fact, the line will always fill up to the minimum level in the tank before the pump is allowed to start.
Yes, your points were already considered because:
TOTAL Static Head = (Discharge Static Head) - (Suction Static Head)
= 30m - 24m = 6m
The heights used are referenced to the pump centerline for simplicity of the example. Also, the pressures on both tanks are equal (both at atmospheric).
Regards,
DD
---engineering your life---
RE: Calculate Total Head
choose pump conditions and just fill out the form, calculates for minimum and maximum conditions as described in the other answers.