Pressure unloader valves are important part of your pump system. Unloader Valves are the traffic directors of your pump and pressure regulator. They serve to direct the flow of water in a pressure washer system. They are used in many plumbing applications as well. When water stops flowing from the nozzle of a spray gun, the unloader valve redirects it for a safe pressure outlet. When the cleaner is in “bypass mode,” water that is not released by the spray gun is diverted back to the inlet side of the pressure pump. It then circulates through the pump and back to the inlet side of the unloader valve. Water is once again either released via the spray gun, or redirected to the pump.
Although cycling prevents the dangerous buildup of pressure, added safety concerns arise during bypass. Most pressure cleaner pumps can withstand temperatures of 140º F. At higher temperatures, damage to the pump can occur. Pump packings, plungers, seals, and even the short bypass hose in external bypass systems may be damaged. Thermal Relief Valves offer some protection against excessive heat buildup. They ensure cool water is released to the pump when temperatures rise. Operators are advised to always take care to prevent overheating regardless of the presence of Thermal Relief valves. Pumps should not be allowed to operate in bypass mode for more than 2 to 3 minutes. Squeezing the spray gun trigger always interrupts cycling and introduces new, cool water to the system.
Unloaders come in a variety of styles like: