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Pressure regulators type 121 and 121 BV

Pressure regulators type 121 and 121 BV – direct acting

Pressure regulator type 121 is direct action device for low pressure, which ensure a constant downstream pressure (p2). The regulator is controlled by a diaphragm and spring. They can be provided with shut-off device for low and high pressure or for high pressure. They can be used with natural gas, LPG, air, nitrogen, etc.


In the absence of pressure, gas pressure regulators type 121 and 121-BV are in open position. Inlet pressure acting upon diaphragm, thus overcoming the spring action, and through diaphragmassembly and lever move the rod with pad unit. When outlet pressure increase up to presset value, the nozzle is completely closed by pad unit. Increasing inlet pressure up to value of completely closed nozzle is defined by lock-up pressure (SG). Gas consuption cause outlet pressure decreasing, and cause opening nozzle by moving pad unit.This is main gas regulator function: Maintaing constant outlet pressure which is defined by accuracy class (AC). Set point pressure is established by the adjusting ring. In order to increase the outlet pressure, rotate clockwise the adjusting ring, and to decrease the outlet pressure rotate counterclockwise the adjusting ring.


Gas pressure regulator equiped with shut-off device is called 121-BV. Protecting the instalation and the consumers after regulator against extreme (high and low) pressure is the basic function of shut-off device (protection against only high pressure upon request). Shut-off device for protection against high and low pressure is type: GT.BM.VNP.02.65.P.Z and for high pressure protection is type: GT.BM.VP.02.65.P.Z. Operation shut-off device for protection against low and high pressure type: GT.BM.VNP.02.65.P.Z is explained in folowing text. Outlet pressure intake through the pulse pipe under the diaphragm assembly. Pressure increasing move the diaphragm assembly upper, through lever cause moving of rod which release the tooth from the rod . The rod under the spring load move the valve disc to close the nozzle. Increasing outlet pressure act uppon diaphragm assembly and overcome the high pressure spring load (VP). Decreasing outlet pressure move the diaphragm assembly down under the low pressure spring load (NP) and through lever move the rod and release the tooth from the rod. Activate pressure is realized by setting springs and by adjusting ring for VP and adjusting ring NP . Rotate adjusting ring clockwise for increase pressure or rotate adjusting ring counterclockwise to decrease activating pressure. Shut-off device is manualy reset by pulling handle. Shut-off device used only for protection against high pressure (type: GT.BM.VP.02.65.P.Z) is equipied without spring NP and adjusting ring for NP.


Technical manual:

Safe use guide type 121

Safe use guide: