In a piping system, it shall be installed a strainer before pump and valves to block the impurities from fluid and make pump and valves in safe operation. The

strainer is usually equipped at the inlet of pressure-reducing valve, pressure relief valve and other main devices to block the impurities from fluid into the pipe

and protect fittings on the piping systems from abrasion and plugging, so that the valves and other devices could be normally working.