Automatic Systems – Flow Switch Versus Pressure Switch
Now that you have decided to purchase industrial pressure washing equipment, how do you plan to start and stop your pressure washer. Your cleaning personnel should have the correct tools to clean without the fear of causing expensive damage to the equipment. Choosing the right pressure washing controls and accessories is the first step. The correct equipment and controls reduces or eliminates costly downtime, service, and replacement parts.
Manual or Automatic Controls?
The type of controls for your electric motor driven pressure washer will depend on who is using the equipment and how.
- A single user with a single hose/gun/wand assembly knows not to leave equipment running when not in use and is usually more careful with the equipment. Manually starting and stopping the unit when required with the understanding of how the equipment works leads to years of trouble free service.
- Multiple users and/or multiple cleaning stations has a greater chance of abuse. Your industrial pressure washing equipment is more likely to require service and parts to repair failed components. Automatic start and stop controls complete with pump high temperature and low inlet water supply safety shutdowns will prevent unscheduled service and repairs.
Flow Switch Start and Stop
Just as the word states the flow of water controls the starting and stopping. The flow of water is caused by pulling the trigger allowing water to spray out the nozzle. When the equipment is not running, a slight leak anywhere in the system such as quick connects, hoses, trigger guns, swivels, or fittings, is usually not enough to causes the pumping package to start unnecessarily. A pumping package that starts correctly and continues to run after the trigger gun is released is a symptom of a leak downstream of the pump. A leak significant enough large enough under high pressure to keep the pump running is not only harmful to the equipment but could also pose a safety hazard. This should be repaired by qualified personnel immediately.
Pressure Switch Start and Stop
In most cases there are usually two pressure switches control the starting and running of the equipment. Some manufactures use pressure switches incorporated into the design of the regulating/unloader eliminating the need of the second switch. Typically the two pressure switches style would have a “pressure trapped regulator/unloader”. This means when you release the trigger gun stopping the flow of water, the high pressure water is “trapped” between the gun and the regulator/unloader. The pump being upstream of the regulator/unloader is not trapped in the high pressure but remains at a lower inlet water supply pressure. With no high pressure water on the pump, the pressure switch shut the unit down. When you release the “trapped” pressure by pulling the trigger on the wash gun the “start” pressure switch activates the pumping package. As the cleaning continues the “start” pressure switch opens up. The “run” pressure switch wired in parallel continues to stay closed with the high pressure in the pump. This system is susceptible to false starts and stops if any leaks are in the systems quick connects, hoses, trigger guns, swivels, or fittings. It is more forgiving and starts easier with smaller nozzles, longer / larger discharge piping systems, or lower than average inlet water pressure supplying the pumping package.
Start-Up and Shutdown
With most industrial units once the trigger on the gun is released, a timer delays the shutdown of the pumping package. This feature allows the operator to adjust or move with the trigger gun in the closed position. Once the safe action has been completed, the operator then pulls the trigger on the wash gun to continue cleaning without the need to restart the pumping package. This eliminates the number of starts for the electric motor greatly reducing contactor and motor wear. This time delay ranges from 2 seconds to 90 seconds depending upon the application and manufacturer.
To learn more about power pressure washer controls, contact HPW Incorporated today at 905-761-8822 or Contact Us.