Determining Suction Lift Pump Height Using Solve Blocks
By D.M. Griffin, Jr.
About this worksheet:
Finds the maximum height above a reservoir that an iron pipe can be placed and maintained with specific operating conditions
Applicable for engineers working with pump manufacturers, pipes, reservoirs, and hydraulics
Performs calculation with net positive suction head (NPSH), Fluids Mechanic, friction, optimum flow condition, solve blocks, symbolics, headloss equation, etc
This worksheet using PTC Mathcad helps you to determine the maximum height that a pump can be placed under a reservoir, and maintain the operating conditions set by a pump manufacturer. In the problem, a pump lifts water into a ductile iron pump from one reservoir into another. You are given the difference in elevation, the performance curve, and flowrate through the system. The pump manufacturer requires the net positive suction head (NPSH) to be 1.5-m. In the worksheet, you must determine the maximum height above the lower reservoir that the pump can be placed and maintained with the same operating conditions.
To solve, the worksheet first shows you how to define the known terms for the schematic and provides you with the calculation to find the net positive suction head. This worksheet uses solveblocks to find solutions. In order to solve, calculations must be made for the higher and lower sections of the pumping system. Symbolics are used to determine an equation for the maximum distance from the pump suction to the water's surface.
This worksheet solves for the solution and determines that the available suction head exceeds the 1.5-m required by the pump manufacturer. This worksheet is an example of how PTC Mathcad can save an engineering firm time and money. All notation, images, data, formulas, and solutions are provided to aid you in your own calculations.