INDIAN RAILWAYS – LIMITING VALVE
The Limiting Valve is designs for installation in a compressed air line to provide a reduced output pressure at a constant valve. It can be used for a wide range of pressure setting with adjusting spring to suit the range. It has a spring loaded synthetic rubber diaphragm, which control an inlet valve so that the output air pressure balances the spring pressure at the set valve. Adjustment of setting pressure with in a given range can be done by an adjusting screw.
OPERATION
In the normal position, the inlet valve (9) remains open due to the load of the adjusting spring (5) below the diaphragm (3). The incoming air enters port “A” And passes into the chamber “J” to Chamber “H” and through the outlet port “D” to the equipment.
An orifice in the valve admits air to the space above the diaphragm. As the pressure in the chamber “J” and “H” increase, the load in the diaphragm increases and forces the diaphragm against the spring at the predetermined pressure setting, the inlet valves closes and is kept seated by the spring (8). The forces acting on the diaphragm are balanced.
When the outlet pressure falls below the setting pressure, the balance is disturbed and the inlet valve opens to admit more air from the inlet poet until the balance is restored when inlet valve closes again.