Pneumatic And Hydraulic Equipment Page 688

Operation of a Typical Regulator Outlet pressure is controlled by the adjusting knob. Clockwise rotation increases and counterclockwise rotation decreases the outlet pressure setting. When the knob is rotated fully counterclockwise, no force is applied to the regulation spring, and the valve is held closed by the valve spring. Clockwise rotation of the knob compresses the regulation spring, which supplies a downward force on top of the flexible diaphragm. The diaphragm and valve pin move downward forcing the valve off its seat, which allows air to flow past the valve to the downstream system. Outlet pressure increases in the down stream system and sensing chamber and applies an increasing upward force on the bottom of the diaphragm. The diaphragm, valve pin, and valve move upward, compressing the regulating spring. Upward movement stops when the forces below the diaphragm balance the forces above the diaphragm. When there is no downstream flow demand, the balance of forces occurs with the valve closed. When there is downstream flow demand, the balance of forces occurs when the valve opens enough to compensate for demand, thus maintaining the desired outlet pressure. Operation of a Pilot Operated (Slave) Regulator with a Conventional Pilot Regulator The pilot regulator controls the pressure in the control chamber of the slave regulator, replacing the spring force as described in Operation of a Typical Regulator above. This pressure causes the flexible diaphragm and valve tube of the slave regulator to move downward forcing the valve off its seat, which allows air to flow past the valve to the downstream system. Outlet pressure increases in the downstream system and sensing chamber and applies an upward force on the bottom of the diaphragm. The diaphragm, valve tube, and valve move upward. Upward movement stops when the forces below the diaphragm balance the forces above the diaphragm. When there is no downstream flow demand, the balance of forces occurs with the valve closed. When there is downstream flow demand, the balance of forces occurs when the valve opens sufficiently to compensate for demand, thus maintaining the desired outlet pressure. Operation of a Pilot Operated (Slave) Regulator with a Feedback Pilot Regulator Operation using a feedback regulator is the same as the conventional regulator except that outlet pressure of the slave regulator is sensed (through the feedback line) under the pilot diaphragm, causing the pilot valve to close when the desired outlet pressure is achieved. The output of the pilot regulator will therefore increase or decrease the pressure into the control chamber as required to maintain a constant pressure downstream of the slave regulator. REGULATOR OPERATION WARNING The feedback line must sense the outlet pressure of the slave regulator and must be connected before turning on air pressure. If feedback line is not connected, slave regulator outlet pressure will rapidly increase to inlet pressure when the adjusting knob on the pilot regulator is turned clockwise. Norgren (314) 427-0600 800-444-0522 (FAX) 314-427-3502 www. j hf.com JHF Catalog [ Volume 7 ] 688 Prices Subject to Change Without Notice John Henry Foster pneumatic and hydraulic equipment

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