The purpose of a relief valve is to release the pressure buildup, also known as backpressure, in a blower system. Backpressure will cause the blower motor to overheat resulting in a burnt out motor and bearing failure. Backpressure is the number one cause of motor failure in regenerative blowers. A simple installation of a relief valve with proper calibration can prevent unwanted and unnecessary blower replacements, saving you time and money. Available in 1.25", 1.5", 2", 2.5", 4", and 5".