Convert pressure and head, calculate discharge pressure from suction and differential rise, or estimate required pump differential pressure. The system model is a turbulent, full-pipe water estimate using Hazen–Williams; changing density does not make it valid for other liquids.

Use a consistent pressure reference. System estimate: water only, turbulent full-pipe Hazen–Williams flow, negligible boundary velocities. It does not check pump curves, NPSH or equipment pressure ratings.

1 models water at 1000kg/m³. System friction remains water-only; a density change does not model viscosity.

Pump Discharge Pressure Formula

The following formula is used to calculate the Pump Discharge Pressure. 

Pdischarge = Pₛuction + ΔPₚump
  • Where Pdischarge is the Pump Discharge Pressure (Pa)
  • Psuction is the suction pressure (Pa) 
  • ΔPpump is the required pressure rise across the pump (pump differential pressure) (Pa) 

To calculate pump discharge pressure, add suction pressure and pump differential pressure using the same gauge or absolute reference. This pressure identity does not include elevation and velocity corrections required for total pump head.

How to Calculate Pump Discharge Pressure?

The following example outlines how to calculate the Pump Discharge Pressure.

Example Problem #1:

  1. First, determine the suction pressure (Pa). In this example, the suction pressure (Pa) is given as 54.
  2. Next, determine the required pressure rise across the pump, ΔP (Pa). For this problem, ΔP (Pa) is given as 15.
  3. Finally, calculate the Pump Discharge Pressure using the equation above: 

Pdischarge = Psuction + ΔPpump

Inserting the values from above and solving the equation: 

Pdischarge = 54 + 15 = 69 (Pa)

FAQ

What is suction pressure in pumps?

Suction pressure in pumps refers to the pressure at which the fluid is fed into the pump (at the pump inlet). It's a critical parameter that influences the pump's ability to avoid cavitation and impacts the discharge pressure.

Why is the required pressure rise (ΔP) important in calculating pump discharge pressure?

The required pressure rise (pump differential pressure, ΔP) is crucial because it represents how much pressure the pump must add to overcome system losses (e.g., elevation/static head and friction) and achieve the desired flow and discharge conditions.

How can incorrect calculation of pump discharge pressure affect a system?

An incorrect calculation of pump discharge pressure can lead to several issues, including inadequate flow rates, potential damage to the pump or system components due to excessive pressure, and inefficient operation leading to increased energy consumption and operational costs.