Weight loaded pressure relief valves are designed to protect the blower against damage caused by operation at greater than design pressure or vacuum (they are NOT intended as pressure regulators). As the service line air pressure reaches the pressure setting, the weight loaded cap is forced upwards of the valve seat. As pressure increase, the cap rises to expose the discharge ports. The flow-through capacity of the valve is such that no damage can be caused to the blower or related systems. The valve automatically reseats itself as line pressure is reduced. Removable weights have been carefully designed to permit accurate pressure settings in ½ and 1 PSI increments; the weights are cut from uniform steel plate or uniformly cast to give accurate pressure adjustment. Available in 1" through 8" sizes