Duplex type strainer is similar to basket strainer and usually consists of two separate strainer baskets housed. They have a cleanable basket that traps suspended solids. Valve is placed between the two baskets to divert the flow of liquid to one strainer while the other is being cleaned. This change-over is accomplished by the use of butterfly valves. Duplex type strainer is installed in the pipeline systems where the flow cannot be stopped such as chemical process systems, lubricating systems, salt, and freshwater systems and fuel lines lubricating systems, sewage water system, cooling water, condensers, compressors, pumps, fire line, and positive suction head service.