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Measure clearly.
Calculate consistently.

Practical SI tools for commissioning checks. Each result shows its assumptions and method so it can be checked against the approved design.

Manufacturer valve-flow calculator ↗HVAC field handbook ↗

CALCULATOR

Pump differential total head

Calculate the energy rise between suction and discharge measurements, including velocity and elevation corrections.

Method and scope

H = (p_d − p_s)/(ρg) + (v_d² − v_s²)/(2g) + (z_d − z_s) + h_remote. g = 9.80665 m/s².

Use gauge pressures with a common reference and a known steady liquid flow. Pressure-tap elevations must match the pressure readings. This is not an NPSH or pump selection calculation.

The pre-filled numbers are illustrative examples. Replace them with measured values or verified project inputs. Calculations do not save data or alter equipment.

Liquid flow (L/s) Same steady flow through both measurement planes.

Liquid density (kg/m³) Use fluid properties at measured temperature/concentration.

Signed suction gauge pressure (kPa) Vacuum is negative. Do not turn it into a positive number.

Signed discharge gauge pressure (kPa) Discharge gauge pressure, not differential pressure.

Local atmospheric pressure (kPa absolute) Used to reject impossible gauge pressures. Use local pressure, not a sea-level weather correction.

Suction internal diameter (mm) Inside diameter at suction pressure plane.

Discharge internal diameter (mm) Inside diameter at discharge pressure plane.

Discharge minus suction pressure-tap elevation (m) Use a common datum; correct remote sensing-line readings first.

Loss between measurement planes and pump flanges (m) Sum known suction/discharge losses only. Zero for flange-adjacent readings.

Reset example inputs

Measure clearly.Calculate consistently.

Pump differential total head

Good buildings start withthe right conversations.

Measure clearly.
Calculate consistently.

Good buildings start with
the right conversations.