Industrial washdown

Pumps for Central Washdown Systems

A central washdown system feeds several cleaning stations from one pump through a common main. As operators open and close spray guns, demand keeps changing, but every nozzle still needs steady pressure.

A pitot tube pump suits this job. Its flat head curve keeps outlet pressure broadly steady from one open station to all of them, and the pressure it generates tops out at its shut-off head.

Below, compare three pump types and see what data you need for selection.

Discuss pump selection

One pump supplies a common main and several cleaning stations. Station valves operate independently.

Cleaning stations

Start with the Cleaning Stations

Separate Hose Washing from High-Pressure Cleaning

Hose stations and central high-pressure cleaning work at very different pressures. Hose stations usually run on mains or lightly boosted water at a few bar. Central high-pressure cleaning systems typically supply about 20–70 bar (approx. 290–1,015 psi). Start with the nozzle pressure needed to remove the product residue, then add the losses between the pump and the nozzle to find the pressure the pump must deliver.

Lower-pressure washing can often use a straightforward booster pump. A central high-pressure cleaning system needs a pump and distribution network selected for the spray guns, hose lengths and simultaneous demand. Cleaning temperature and any chemical addition also affect the equipment selection.

Count the Guns That Run Together

Total installed stations and simultaneous stations are different numbers. Add the flow needed by the guns that will be used together to find the required delivery flow. Check the smallest expected working demand as well, so the selection covers a single active station and the normal cleaning pattern.

Use each nozzle's flow at its specified pressure: nozzle size changes water demand. Agree the cleaning sequence with the plant team before choosing the pump.

Allow for the Distribution Network

The pump must supply the nozzle pressure plus the losses between the pump and that nozzle. Long branches, small pipes, fittings and elevation add to the required head. Review the most demanding station with the expected combination of open guns, rather than only the outlet pressure beside the pump.

Pump choices

What Happens When Fewer Stations Are Open?

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Pump response and pressure control in multi-station washdown
Pump arrangement	Response to changing demand	How pressure is managed	What to include in the selection
Plunger pump with unloader or bypass	At a fixed speed, the pump delivers nearly the same flow. When guns close, the extra flow needs another path.	An unloader or regulating valve diverts flow to control the pressure. Variable-speed control is another possible arrangement.	Valve and packing maintenance; energy used during bypass operation; heat added to recirculated water.
Multistage centrifugal pump	At a fixed speed, pressure generally rises as flow falls. The actual change depends on the pump curve.	A pressure sensor and variable-speed drive can adjust speed as stations open or close. A minimum-flow return may be needed.	The operating curve, minimum-flow requirement, sensor position and control response.
Pitot tube pump	A flat head curve keeps pump outlet pressure broadly steady across changing flow at a fixed speed.	Pump-generated pressure reaches its maximum at shut-off head. A pressure-relief valve is not needed to prevent the pump from generating pressure beyond that head.	The required head and flow range, inlet conditions, nozzle flow and pressure, and distribution losses.

Plunger Pumps: Control the Surplus Flow

A plunger pump is a positive-displacement pump. When operators close some guns, the pump still moves water at nearly its previous rate. An unloader or bypass arrangement gives that surplus water a return path and keeps the working pressure under control.

With the right controls, a plunger system can deliver steady cleaning pressure. The trade-off is the additional valve workload and the energy spent circulating water that is not reaching a cleaning nozzle. Recirculation can warm the water, particularly when a large share of the output returns through a small circuit. Include valves, seals and packing in the maintenance plan.

Multistage Pumps: Match Speed to Demand

Multistage centrifugal pumps are useful for boosted-water systems. A pressure transmitter and variable-speed drive can reduce pump speed as demand falls, rather than delivering all the flow through a bypass. The control system should respond to the stations that actually need pressure.

At small flows, check the minimum-flow requirement and return line. Cover normal demand and quieter periods with fewer active guns.

Pitot Tube Pumps: Use the Flat Head Curve

A pitot tube pump produces high head in a single stage. Water rotates inside the rotor assembly, and the stationary pickup tube recovers that energy as discharge pressure. Its flat head curve is useful for multi-station washdown because outlet pressure changes relatively little as the number of active guns changes.

The pump rotates continuously and delivers low-pulsation flow. It has no plungers or internal suction and discharge valves. Its mechanical seal is on the low-pressure inlet side. These features make it a practical option where cleaning stations switch frequently and the required pressure is high relative to the total flow.

The maximum pressure generated by the pump is set by its shut-off head at the selected speed and inlet conditions. It does not need a pressure-relief valve to prevent it from generating pressure beyond that head. Select the distribution system for the nozzle pressure and pipe losses across the working range.

Plunger + Unloader/Bypass

Fixed speed; pressure held by valve control

Multistage Centrifugal Pump

Fixed speed

Pitot Tube Pump

Fixed speed

The plunger line shows pressure held by bypass control. Fixed-speed multistage pressure varies with flow; variable-speed control can flatten that response. The pitot tube curve is naturally flatter. The lines compare response shapes, not pressure levels between pump types.

Pump range

Where an EHIK Pump Fits

EHIK's standard range covers flow rates of 0.05–70 m³/h (approx. 0.22–308 US gpm) and heads up to 1,050 m (approx. 3,445 ft). A central washdown system fits this range when several stations need high pressure, the number of active stations changes often, and the total flow remains relatively small.

Pump head is stated in metres; cleaning requirements are usually stated as nozzle pressure. Include water temperature, inlet pressure and distribution losses. Compare the proposed pump curve with the working flow range.

For low-pressure hose stations, an ordinary booster pump is often simpler. For cleaning pressures beyond the pitot tube pump's range, a plunger pump can be the better choice. Compare the complete arrangement, including its controls, bypass flow and maintenance needs.

See the pump series table ↗

Prepare your data

Data to Prepare for Selection

Stations: installed stations, the number used together, and the usual cleaning sequence.
Nozzles: flow per gun and required pressure at each nozzle.
Water: temperature, quality, particles and any cleaning chemicals. Include the chemical concentration and where it is added.
Pipework: main and branch lengths, pipe diameters, fittings and elevation changes. A layout drawing helps identify the most demanding station.
Supply: available inlet pressure, water source and NPSH available when known.
Power: site voltage, frequency and any requirement for variable-speed operation.

A question is enough to begin. EHIK can review your requirements and propose a pump, drive and supply package once the operating conditions are defined.

Field installation

A Related Installation: Xiawang Paper

EHIK pumps serve central flushing at Xiawang Paper, supplying several flushing outlets from one pumping installation. The paper-industry page shows the installation and site photographs.

See paper-industry pumping applications.

Questions

Common Questions

Can one pump supply stations that open and close independently?

Yes. Select the pump and distribution network for the required nozzle pressure, simultaneous flow and smallest working demand. A pitot tube pump's flat head curve helps keep pump outlet pressure broadly steady as the number of open stations changes.

Does a pitot tube pump need an unloader or pressure-relief valve to prevent overpressure?

The maximum pressure generated by the pump is limited by its shut-off head at the selected speed and inlet conditions. It does not rely on an unloader or pressure-relief valve to prevent it from generating pressure beyond that head.

Can EHIK pumps handle hot cleaning water?

EHIK's standard liquid-temperature range reaches 260 °C (500 °F). Selection for hot cleaning water includes its actual temperature, inlet pressure, materials and mechanical seal. Tell EHIK whether the pump handles plain water or a cleaning solution.

What should I send first?

Start with the number of stations used together, flow per gun and nozzle pressure. Add water temperature and a pipe layout when available. Inlet pressure, NPSH available and the site power supply make the selection more complete.

Your system

Plan Your Central Washdown System with EHIK

Send the cleaning-station requirements and the operating data you have. EHIK replies within 1 business day. Once we have the operating data, we send a quotation and technical proposal within 3 business days for pumps, or 5 business days for pump skids.

Discuss pump selection