Calculation aids & planning tools Calculate with the formulas from the technical book "Abwasserpumpen – Technik, Planung und Betrieb" (wastewater pumps – technology, planning and operation)
Five calculation aids for the design of wastewater pumping stations. Every formula is derived in the technical book; the reference is given with each tool. The order follows the planning process – from the pump curve via the suction side to the discharge side and operation.
nq
Specific speed
Classifies the hydraulics – radial, mixed-flow or axial – and what this means for the pump curve and part-load behaviour.
Technical book, chap. 3.4.1
NPSH
NPSH check
Compares the NPSH available in the system with the NPSH required by the pump and shows the safety margin.
Technical book, chap. 3.3.2
n₂/n₁
Affinity laws
Converts flow rate, head and power of the pump curve to a different speed.
Technical book, chap. 3.4.5
Δp
Pressure surge (Joukowsky)
Estimates the pressure surge caused by a rapid change in flow and assesses whether a detailed surge analysis is required.
Technical book, chap. 3.7.2
VN
Switching volume & starts per hour
Determines the effective volume of the pump sump so that the motor stays within its permissible number of starts.
Technical book, chap. 4.1.6
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Derivations, boundary conditions and worked examples for all tools can be found in the technical book.
Request the technical bookNote: These calculation aids are intended for estimates in preliminary planning and do not replace a detailed design. Responsibility for their application remains with the user.