Safety Valve is one of the most crucial accessories in a chemical dosing system. It is also referred as pressure relief valve in the industry. Safety valve helps to prevent system being over pressure. In a typical setup, it shall be installed along the return pipeline after the metering pump. While installing a safety valve, it shall be installed as close as possible towards the dosing pump and there shouldn’t be any valve in between. When the pressure in the system pipeline exceeds the preset value, the diaphragm and the shaft are jacked up, and the medium is discharged back to the return pipe. The preset value can be adjusted directly on the safety valve itself. The preset value can be adjusted within 0 – 1Mpa by adjusting the adjustable nut. The relief pressure is generally set higher than the system pressure by 0.1-0.2Mpa and not exceeding the maximum pressure of the metering pump.
Back pressure valve is very similar to safety valve, but the emphasis is on steady state pressure control instead of on/off actuation. It shall be installed on the positive pressure side along the discharge pipe of the metering pump. A back-pressure valve can prevent the occurrence of siphoning and reduce unstable dosage which is caused by the pressure fluctuation. To adjust the set value, remove the protective cap, rotate the adjusting nut, and set within the range of 0-0.6 MPa. It is commonly used in conjunction with the pulsation damper to reduce the vibration damage towards the system. On the discharge, the flow will be more stable with the installation of back pressure valve.