Low pressure reducing valves control secondary pressure (p2, behind valve). Low pressure reducing valves ZM-R/D and LPR/D are controlling protective gas or inert gas to isolate processes from contamination by atmospheric oxygen.
ZM-R/D and LPR/D is a spring loaded differential pressure regulator with reference to actual atmospheric pressure via a sensor hole to ambient. Under non operating conditions, the atmospheric pressure the adjustable range spring and a lever mechanism hold the valve open. Under operating conditions, gas enters from primary (p1) through the valve and reaches counter side of diaphragm via a Venturi-tube. As a result, the differential pressure is exactly in balance with the force of adjustable range spring. The valve will be closed as soon as secondary pressure (p2) raises set point of adjustable range screw. Valve will be open again, with secondary pressure below set point. Valve seat tightness is at least according to VDI/VDE 2174. Optional C-connection is used for pulse line connection in case of long pipes and/or high gas flow rates to compensate dynamic pressure drop. Optional D-connection s used for pilot line connection in case of dome loaded service (high pressure blanketing). ZM-R/D and LPR/D is vacuum-proof, manufactured in decreasing design and uses no external energy. Depending on application, the units are performing with or without pulse and/or pilot line.
The low pressure reducerZM-R/D and LPR/D works similar to LPS. But in addition, a dome pressure of up to 2000 mbar relative can be applied via “D-connection”. So the regulator can be used with higher reference pressure to "blow-out" vessels for example. A pneumatic control unit can be offered and delivered accordingly.