Bellofram Type 75HR High Relief Pneumatic Air Relay

The Type 75HR Pneumatic Air Relay from Marsh Bellofram uses signal pressure to accurately manipulate output pressure over an expansive range of flow and supply pressure variations. Under these varying flow conditions, output pressure is regulated by use of an aspirator tube, which changes the air supply valve opening in accordance with flow velocity. A balanced supply valve, utilizing a patented Marsh rolling diaphragm, makes the relay virtually unaltered should changes in supply pressure occur, with reliable operation over millions of cycles.

The Type 75HR relay is the high-relief version, delivering extra fast “blowdown” for quick release of output pressure. This relief feature makes the relay ideal for use in applications demanding rapid exhaust. More still, the unit is available with an internally spring mounted fixed negative bias, with a formula that is particularly useful for obtaining zero pressure from pneumatic devices such as I/P transducers, which cannot normally be adjusted this low, as well as obtaining higher outputs from such devices. The design and construction of the Type 75HR relay require little maintenance and prevent downtime as units are able to be serviced without being removed from the line. Signal to output pressure ratios of 1:1, 1:2, 1:4 and 1:6 are available. Maximum output is 150 PSIG (10.3 BAR).