Articles for Contractors

Breaking Down the Pressure Washer

What Type of Pressure Washer is Right for Your Business? We Break Them Down

Cold-water pressure washers are the most popular, probably primarily due to cost and ease in manufacturing and use. They are generally limited to 140 degrees Fahrenheit from a hot water tap. They are broken into two types: electric or gas engine.

1. Electric are more compact and lower performance when electric current is limited to 115 volts. They are more economical and sold to consumer markets or for semi-professional use.

2. Gas and diesel engine units are more portable and used primarily outside when noise and gas fumes do not present a problem.

Performance is limited by the price you are prepared to pay to get the job done. EnviroSpec’s power washers are the industry’s most powerful and easiest to maintain. They are built exclusively for the professional contract cleaning industry. They are expensive on the front end but are much less expensive over the long distance. They last much longer that standard power-washing equipment.

Hot water units are primarily used for professional or industrial applications where high temperature is required to break down dirt more effectively. Because they consist of an oil burner and heating coil, they tend to be more expensive and complicated to operate. They have, however, enjoyed probably the largest percent sales growth in the industry due to more efficient manufacturing and promotion.

Most pumps have a dual-packing design with a water recycling system, allowing water to lubricate packings and bleed back minor leakage from slightly worn packings. When excessive wear occurs and pressure drops significantly, packings should be changed. Remember a new pump will sometimes weep slightly until packings take a good set against plungers.

The pump crankcase is very trouble free — like an automobile if properly maintained. Oil should be changed after initial a 50-hour break-in period and every 500 hours or annually thereafter or when oil gets milky. This could be caused by condensation from temperature changes or oil seal leakage, which may occur if vented crankcase plug is not installed and seals are sucked in from vacuum created when oil heats up.

  • Filters — A good inlet filter is a cheap price to pay to protect your pump from impurities that are in water. Rust, scale, and sand easily can clog valves or scratch plungers. Use a 60 to 100 mesh screen of adequate size for flow and be sure it is checked and cleaned periodically.
  • Pressure Gauges — These gauges are generally not used by most manufacturers as they tend to malfunction easily unless more expensive glycerin-filled ones are used and they add to machine cost. They do, however, serve an important role as a ready warning to nozzle wear or pump seal damage, which reduces effective cleaning and potentially leads to more expensive repair later. In a professional contractor environment, a pressure gauge is highly recommended.
  • Unloader Valves — The main safety component of a pressure washer. It along with the trigger gun, uploader valves literally control the traffic flow of water in the system. Without an unloader valve, when gun is shut off, pressure will continue to rise until either the engine stalls or the pump, hose or gun ruptures. Unloaders divert all or part of the flow to a supply tank or the inlet of pump to prevent pressure from building up. When the gun is opened, water moves from the outlet of the pump through the hose to the gun and nozzle. When the trigger is released, the valve closes and the unloader is activated, either by an increase in pressure (pressure-actuated type) or a reduction in flow (flow-actuated type). Water flows into the channel and pushes the piston down, which opens the bypass valve. The unloader diverts flow of water from outlet side of pump back to inlet side, causing water to flow back to pump virtually under no pressure.

The advantage of a flow-actuated unloader is that hose and pump pressure is reduced in unload mode. This is safer for the hot water coil, and when the operator doesn’t want a fast kick-back when the gun trigger is depressed. A flow-actuated unloader, however, can’t be used on multigun systems and is generally more expensive and sensitive to adjust.

The pressure-actuated type is the common. It traps pressure in the hose in unload mode so immediate pressure is available when the gun is opened.

The pressure of the system can be controlled to some extent by adjusting the tension on the spring holding the piston in the valve in place. Changing the nozzle is the preferred method of controlling pressure, and the unloader should only be adjusted to fine-tune the system.

If the unloader valve goes on/off when gun is shut off, either the spring is not properly adjusted or there is a leak in the hose, gun, or connections. Spring tension that is too tight can be hazardous because pressure spikes before it unloads.

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