Copyright Goodheart-Willcox Co., Inc. 410 Fluid Power operating pressure of the regulator is set by tightening the adjustment screw to compress the control spring. This applies force to the atmospheric side of the dia- phragm. Application of this force moves the transfer pin, which opens the poppet valve and compresses the valve spring. System air is then allowed to move through the valve to the outlet port and on to the actuator. When the actuator encounters resistance, the pres- sure of the incoming air begins to increase. This pro- duces force in the actuator that attempts to move the actuator load. At the same time, the pressure in the out- let port of the regulator increases. This produces a force on the system side of the diaphragm, which begins to balance the force applied by the control spring. When the pressure reaches the setting of the regu- lator pressure, the force generated on the surface of the diaphragm overcomes the control spring force. This allows movement of the diaphragm. When the dia- phragm moves, it no longer applies force to the pop- pet valve through the transfer pin. The valve spring can then adjust the valve. The adjusted valve posi- tion allows only suffi cient air to pass to maintain the desired working pressure. If the air-powered equipment does not need air, the pressure climbs to the regulator setting and the valve completely closes. If there is a need for air, the regula- tor adjusts until only suffi cient air is allowed through the valve to compensate for the required fl ow. This regulator design provides pressure control but directly exposes the diaphragm to system airfl ow. This exposure subjects the diaphragm to any foreign materials in the air, which may shorten the life of the component. Direct exposure also affects regulator accuracy and sensitivity. When the regulator is installed, the inlet port is connected to a line from the air distribution system. The outlet is connected to the workstation line contain- ing the pneumatic-powered actuators. The maximum Outlet port Transfer pin Inlet port Valve spring Poppet valve Control spring Adjustment screw Diaphragm Goodheart-Willcox Publisher Figure 16-18. The diaphragm of a direct-operated pressure regulator is directly exposed to the pressurized air in the outlet port. Outlet port (reduced pressure) Inlet port (supply pressure) Diaphragm-control chamber Sensing orifice Goodheart-Willcox Publisher Figure 16-19. The diaphragm of a basic, diaphragm-chamber regulator is separated from the direct airflow through the valve. The pressure in the outlet port is transmitted to the diaphragm through a pressure-sensing orifice in the valve body.