Technical Support
Choosing the Right Pump

Choosing the correct pump for an application should not be difficult if a few basic preliminary steps are followed.
• Volume and pressure requirements of the system
• Type of material being pumped – oil, fertilizer, insecticides, chemicals, and at what temperature
• How the pump will be driven and at what speed – PTO, engine, electric motor or hydraulic motor
• Check HP requirements of power unit for system pressure and volume

Diaphragm Pumps
A diaphragm pump is a positive displacement which means flow stays constant with speed. Flow is also variable with change of speed. This type of pump is reliable and compact compared to other pumps that have similar flow and pressure ratings. These pumps are excellent for agriculture, industrial, lawn care and nursery requirements because of their adaptability to spraying conditions.
• Wide range of flow and pressure specifications
• Low maintenance and almost wear-free operation
• Self-priming
• Handles wide range of materials that would damage other pumps such as corrosive chemicals, wettable powders and other abrasive solutions.

Roller Pumps
A roller pump is similar to a vane pump except it utilizes multiple rollers in place of sliding vanes. Its unique design adapts to a variety of spraying applications, especially for the lower PTO speed requirements of agricultural spraying systems.
• Low initial and maintenance costs
• Operates efficiently at PTO speeds
• Good priming characteristics
• Compact size in relation to capacity
• Easily mounts

Centrifugal Pumps
Centrifugal pumps are very popular because of their versatility. They provide high capacities and handle abrasive and wettable powders. Centrifugal pumps require higher operating speeds which make them ideal for small engine applications of liquid transfer.
• Handles suspensions well
• High capacity
• Low maintenance
• Low pressure characteristics, pressure only needs to be controlled by by-pass valve
• Some designs can handle solids

Piston Pumps
A piston pump is a positive displacement pump which means it delivers variable output in proportion to its driven speed. It also develops the higher pressure needed for washing equipment, injecting chemicals, and other agricultural and industrial needs that require long life and dependability.
• Wear resistant
• Positive displacement
• High pressure capability
• Good priming characteristics
• Handles various chemicals, wettable powder suspensions, and other abrasive liquids

Pressure Washer Components

Creates flow in the system
Sized to the pumps output flow to obtain desired output pressure. Using nozzles, with different orifice sizes, with a fixed flow rate, can change output pressures.
Unloader Valve
Pressure actuated plunger bypasses flow under low pressure to the intake side of pump when the trigger gun is closed. This relives engine load. Opening trigger gun allows unloader to redirect water to the gun.
Pressure Reducing Valve
Lowers inlet water pressure to allow upstream chemical injection to operate.
Pulsation Dampener
Reduces water hammer and smoothes output flow reducing wear on components,
Bypass Hose
Directs water from unloaded to inlet side of pump.
Prevents foreign matter from entering system.

Pressure Washer with Downstream Injection
Chemical Injection
Chemical injectors provide a mechanical means of introducing chemical into the water stream. The addition of chemical provides better cleaning results while saving time and water consumption. This chemical can be introduced into the water stream by either upstream (before the pump) or downstream injection.

Methods of Chemical Injection

  1. Three way selector valve to select between chemical tank and rinse water.
  2. Chemical injector on inlet.
  3. Pump mounted injector.


  1. Chemical injector on outlet side of pump.


Upstream chemical injection allows user to inject the chemical at high pressure. Chemical is metered or controlled by a valve mounted at the injector. Operator must return to pressure washer to operator injector.
Downstream injection allows operator to control injection at the gun. Chemical is introduced into the water stream at a reduced pressure (normally less that 250 PSI) by increasing nozzle opening size. At reduced pressure, water passes through a venturi drawing chemical with it to the gun. At high pressure water still passes through the venturi but it closes a check valve preventing chemical flow.