Parker 134 Series relief valves are diaphragm type valves that relieve excess pressure, thereby protecting pneumatic circuits and systems. These relief valves are ideal for applications where gradual proportional relief is required. They feature a compact design for narrow spaces and top adjustment knob to adjust relief range. The adjustment knob can be locked / unlocked via a push-pull mechanism and can be rotated in both clockwise & counter-clockwise directions to stop and start bleeding, respectively. These valves have a sensitive diaphragm for accurate operation.