Inlet Feed Tank Versus Variable Speed Drive

For Industrial Pressure Washer Equipment

The number one reason for considering an inlet water tank versus a variable speed drive (VFD – variable frequency drive) for the electric motor is: The application does not require the full capacity (GPM – gallons per minute) of the pump at all times. The entire flow of the pumping package is required only at certain times or when certain conditions happen. Examples of this type of applications are:

  • Multi Trigger Guns or Many Cleaning Stations
  • Process Demands
  • Testing Procedures

In the case of multi gun applications, a standard pump motor configuration uses the regulator / unloader to control the flow, and by default the pressure, to each cleaning station. If the system is sized for 4 trigger guns to be used and only 1 trigger gun is used, the extra capacity or GPM of water produced is directed back to the inlet or suction of the pump via a “bypass” hose. As the word implies, the “bypass” is the amount of water not required, and bypasses the discharge water not used back to the pump. If this bypass flow to the inlet of the pump becomes excessive, the energy in pumping this water will appear as heat in the bypass water. Pump damage will occur if this hot water is allowed to exceed the rated specifications of the pump. It is still possible to over heat the water to the pump without having a heater in the high pressure water system.

The addition of an inlet water tank and the bypass water plumbed back to the tank will allow the cooler tank water dissipate the heat generated in the bypass water. The addition of a variable speed drive would control the flow of water required, eliminating not only the bypass water but the heat generated. In both cases if the system is designed correctly the effects of the heating bypass water has no ill effects on the pumping system.

Why do some systems HPW Incorporated sells use both?

There are applications where not only do flow rates of the system vary, but inlet supply water to the industrial pumping package can not keep up with the demand. Lack of water will cause the pump to cavitate even with the VFD controlling the volume of water used at the cleaning stations. More than one problem can be solved when the use of the inlet tank and VFD are added to the system. The manufacture of the pump (AR, Bertolini, CAT, Comet, Giant, General, Hydra-Cell, Interpump, Pratissoli) will not correct this type of problem. The system must be designed correctly for the industrial pressure wash components to work trouble free.

What components are at risk of premature failure with excessive bypass?

  • Regulator / Unloader
  • Pump seals from water entering the pump in a turbulent manner
  • Pump plungers from heat or cavitation

Contact Us to analyze your application and help you find the best solution to meet your pressure washing or pumping package needs. For professional industrial pressure wash equipment, pumps, accessories, parts, and service, we at HPW Incorporated are here to help.

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