Ross Mackay Forum Moderator 94 Posts
Re: Calculate static discharge head16 January 2007 at 1:29pmYour numbers are confusing, but here's the rule. The Total Dynamic Head required from a pump is as follows:
TDH = Static Head + Friction Losses + Dynamic Head
The static head is measured from the free surface of the liquid in the supply source to the free surface of the liquid in the discharge chamber, or to the highest point in the line.
As you do not identify the elevation of the free surface of the liquid in the supply source, we can only advise you on the discharge static head, which is only half of the total static head.
If we assume a static head basis of the pump centerline, then there are two discharge static heads; one when the highest point in the line becomes a factor at 6.0 m. above ground elevation. The other is when the high points in the line become full of liquid, a siphon effect kicks in, and the lower discharge static head reverts to 2.0 m. above ground elevation.
The friction losses must include all friction losses in all piping, valves and fixtures in the line. The dynamic head is the increase in velocity within the pump itself. I trust this will help you complete your calculations.
How do you determine static discharge head? Additionally, I have a pump at ground level. Its center line elevation is 0.7 m from the ground. The discharge line goes on the rack at 6 m elevation and travels 100 m. The discharge point elevation from ground is 2 m. Please suggest the correct static discharge head from following cases: Ans 1: 2 - 0.7 = 1.3 m Ans 2: 6 - 0.7 = 5.3 m In this case, my final destination is 2 m from the ground, but my discharge line has to travel 6 m up on the pipe rack. Therefore, it is necessary to consider the second option. In this case, if my total head (developed head) is greater than 6 m or 5.3 m (i.e. max manometric head of system), then the pump will work and it will not be necessary to consider 5.3 m as static discharge head. Please clarify.
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