I Inlet shapeType 75 fBehindDocument 1 pWrapPolygonVertices 8;8;(21493,0);(10261,0);(10261,12589);(0,12589);(0,21500);(19888,21500);(19888,20268);(21493,20268) posrelh 0 posrelv 0 pib _1- Inlet pressure switch A common way of sensing tank pressure and controlling actuation and de-actuation of a relatively small (10-15 HP) compressor, is with a pressure switch. Large compressors use other means of various types. what a pressure switch consists of A pressure switch basically consisis of a body, a piston biased by a spring, and electrical contacts. how a pressure switch works System pressure is sensed at the bottom of the piston through the pressure switch inlet. When pressure in the system is at its low level, the spring pushes the piston down. In this position, a contact is made causing an electrical signal to turn on the compressor. As pressure in the receiver tank rises, it forces the piston upward. With system pressure at its high level, the piston breaks the electrical contact shutting down the compressor. safety relief valve Maximum pressure developed by a compressor is designed to be regulated by a control system which senses discharge or tank pressure. In case of an emergency, as the failure of a control system to function properly, a positive displacement compressor system is generally equipped with a safety relief valve. what a safety relief valve consists of A safety relief valve consists of a valve body with inlet and exhaust passages and an internal moving part. In the illustration, the moving part is a poppet which is held biased in one position by a spring. how a safety relief valve works A safety relief valve is a normally closed valve. The poppet of the safety relief valve is seated on the valve inlet. A spring holds the poppet firmly on its seat. Air cannot pass through the valve until the force of the spring biasing the poppet is overcome. Air pressure at compressor outlet is sensed directly on the bottom of the poppet. When air pressure is at an undesirably high level, the spring will be compressed, the poppet will move off its seat, and air will exhaust through the valve. Safety relief valves on a compressor are not intended to be operated frequently. They are a safety device. Many times safety relief valves are equipped with whistles or horns to alert personnel that something has failed or a problem exists. pressure regulator In a pneumatic system, energy which will be used by the system and transmitted through the system, is stored as potential energy in an air receiver tank in the form of compressed air. A pressure regulator is positioned after a receiver tank and is used to portion out this stored energy to its leg of a circuit.
Want to see the other 2 page(s) in scan0029.rtf?JOIN TODAY FOR FREE!