Water Jet Calculators
8 free calculators for sizing pumps, washers, nozzles and hoses — the same tools our engineers use every day.
Power Calculator
Motor power needed to drive a pump at a given pressure and flow rate.
How it is calculated
P (kW) = p (bar) × Q (L/min) ÷ 500. This is the hydraulic power (p × Q ÷ 600) with about 83 % pump efficiency. 1 kW = 1.341 HP. The standard motor is the next IEC rating at or above the required power.
Nozzle Size Calculator
Orifice diameter and the closest standard nozzle size for your pressure and flow rate.
How it is calculated
d = √( Q ÷ (0.6669 × Cd × √p) ) per nozzle, with discharge coefficient Cd = 0.82. The standard size is the nozzle whose rated flow at this pressure is closest to yours.
Pump Flow Calculator
Actual output of a triplex plunger pump from its plunger size, stroke and speed.
How it is calculated
Q (L/min) = π ÷ 4 × d² × s × (n ÷ i) × z × η ÷ 1,000,000 — d plunger diameter and s stroke in mm, n input speed, i reduction ratio, z number of plungers, η volumetric efficiency.
Plunger Diameter Calculator
Plunger diameter needed to reach a target flow rate with a given stroke and speed.
How it is calculated
d (mm) = √( Q × 4,000,000 ÷ (π × s × (n ÷ i) × z × η) )
Crankshaft Stroke Calculator
Crankshaft stroke needed to reach a target flow rate with a given plunger size and speed.
How it is calculated
s (mm) = Q × 4,000,000 ÷ (π × d² × (n ÷ i) × z × η)
Recoil Force Calculator
Reaction force the operator feels at the gun or lance.
How it is calculated
F (N) = 0.236 × Q (L/min) × √p (bar)
Hose Pressure Loss Calculator
Pressure lost along a high pressure hose, and the pressure left at the outlet.
How it is calculated
Darcy–Weisbach: Δp = f × (L ÷ D) × ρv² ÷ 2, with the Blasius smooth-hose friction factor f = 0.316 ÷ Re^0.25 (64 ÷ Re when laminar), water at 20 °C.
Unit Converter
Convert pressure, flow, power and length units used on pump and washer data sheets.