82
Hydraufics and Pneumatics
Pressure ~
1
Droop
....
~- Flow
Response of simple pressure regulators
Figure 3.28
main diaphragm. This space can, however, be vented to the exit side of the valve by the small ball valve. If outlet pressure is low, the pilot diaphragm closes the ball valve causing the main diaphragm to be pushed down and more air to be admitted to the load. If outlet pressure is high, the pilot diaphragm opens the ball valve and the space above the main diaphragm de-pressurises. This
Adjusting screw
Pressure setting spring Pilot diaphragm Ball Orifice
Pressure sensing line Main diaphragm
Pressure line Diaphragm .._rises to vent outlet via hollow stem
Light spring Outlet
Inlet
Vent Valve pushed down to raise outlet pressure
Figure 3.29
Hollow valve stem
Pilot-operatedregulator