Most compressed air systems require at least one regulator, and in many situations they require a large number of these devices. A pressure regulator is a control device that takes a high input pressure and lowers it to a usable output pressure. The most important regulator in the system is the master regulator, which is responsible for controlling the primary pressure in the entire distribution system. These regulators are usually placed on the output of the primary receiver. Generally the output of a master regulator should be set at 90 psi. It should also be noted that the regulator’s flow rate must be ample to deliver full pressure even during peak surge conditions. Agood rule of thumb is to select a master regulator that is capable of delivering a flow rate that is at least five times the flow rate of the compressor. If you have a 10-hp compressor with a rating of 38 SCFM, then a regulator should be selected that has a flow capacity of 380 SCFM. above Figure shows a typical master regulator. Smaller regulators are applied at the different application sites as necessary.
above Figure shows a sectional view of a pressure regulator. Highpressure air is introduced to the high-pressure cavity via the input port. The poppet and seat provide a valve that is used to control the flow of air into the low-pressure cavity. The top of the low-pressure cavity is in the form of a diaphragm. The diaphragm is backed with a preload spring, which can be adjusted via an adjustment screw and knob. When a preload is applied, the diaphragm pushes the poppet down and allows air to flow from the high-pressure cavity to the low-pressure cavity. When the output pressure becomes high enough, it applies a force to the diaphragm that counters the preload spring and stops or restricts the flow between the cavities. Pressure regulators generally have two additional gauge ports that allow the operator to monitor the input and output pressures.