I. Overview When metering pumps and other positive displacement pumps operate at low system pressure, there will be an excess of transport. To prevent similar problems, the import and export must be at least 0.7Bar metering pump backpressure. By installing a back pressure valve in the metering pump outlet pipe can achieve their goals. Second, the main function 1. Provide a back pressure valve pressure difference at both ends of the line is not very demanding 2. The system can be used as safety valve. 3. and pulsation dampers with the use of the system to reduce water hammer hazards, reducing the flow rate fluctuation of the peak, protection pipes, elbows, joints from impact pressure fluctuations. 4. create a good working environment for metering pumps and improved pump performance. Third, the working principle of the back pressure valve by spring force to work. When the system pressure than the set pressure hour, under the action of the diaphragm spring force to plug the pipeline; large when the system pressure than the set pressure, the diaphragm compression springs, pipes connected, through the liquid back-pressure valve. Fourth, the use of back-pressure valve in the outlet line, back-pressure valve and a pulsation damper should be used simultaneously to absorb traffic spikes between the pump and the back pressure valve with a pulsation damper. When no pulsation damper, back pressure valve with each pump stroke progresses quickly open and close. When pulsation damper, back-pressure valve in half-open and half-closed position of oscillation, thus reducing pulsation damper can wear rate of back pressure valve. For large flow pump, and the outlet pipe long, thin, back-pressure valve installation location should be close to filling point to reduce the siphon trend. When liquids containing suspended solid medium, back pressure valve should be installed with the inlet end of the three-way pipe plug (or four), so in the case of the pipeline can be cleaned without disassembly. Back pressure valve just a pipe element, only with other pipeline components (such as pulsation damper, safety valve, check valve, globe valve) used in conjunction to achieve maximum effectiveness. V. Selection Guide diameter pipe have DN10,15,20,25,32,40,50,65,80,100 ten models. The inlet end of the pressure 0.3MPa and 1.0MPa have two series, import and export side pressure differential can be adjusted by adjusting the length of the spring. Materials are PVC (P), SS304 / 316 stainless steel (S), carbon steel (A) provide import and export threaded coupling, flange, hose connectors three ways for selection. Based on the company's previous experience, process information available information and professional users, the company will provide users recommend material contact parts material, determined by the user selection of materials. The company does not bear the loss due to wear or corrosion and damage caused by parts or product warranty. VI Notes 1, to avoid system resonance. 2, simultaneously with the pulsation damper, the pulsation damper to be safe back-pressure valve between the pump and to absorb traffic spikes between the pump and the back pressure valve. Slow the wear rate of back pressure valve. 3, outdoor use should be added protective shed or protective cover. 4, the back pressure valve prior to any maintenance, you should stop functioning equipment, the release of pressure, close the back pressure valve valve associated with the system, while recognizing that there is no pressure pulsation damper. Pay attention to prevent harm to human transmission fluid maintenance. 5, if the back-pressure valve import and export access, back pressure will grow exponentially, bringing harm to the system and may be dangerous. 6, running back-pressure valve malfunction was found should be promptly cut off the power. Warning: The back-pressure valve prior to any maintenance, you should stop functioning equipment, the release of pressure, close the back pressure valve valve associated with the system, while recognizing that there is no pressure pulsation damper. Pay attention to prevent harm to human transmission fluid maintenance.