Strainers

Strainers are devices that are placed in-line with process piping to remove large solid contaminants from the flow. They can be cleaned and reused and can be supplied as either an assembly or an element. Strainer assemblies come equipped with a housing, cover or case, and a strainer element. Strainer elements, when sold separately, do not come as a complete assembly. A strainer element is a simple mesh or perforated metal element that may be used as replacement or a handheld strainer. Strainers can be used in a wide variety of applications, including but not limited to: general purpose, chemical, coolant, food processing, laboratory, industrial, high temperature, high viscosity, hydraulic fluid, medical or pharmaceutical, oil or fuel, refrigerant and water.

There are different types of strainers used in fluid-flow applications to capture sediment, debris, scale, etc. that might otherwise clog downstream equipment or contaminate products. The principal types of industrial strainers in common use include: Simplex Strainers, Duplex Strainers, Y-type Strainers and Temporary or Start-up Strainers.                                                                                       Simplex strainers require shutdown or isolation of the line before they can be cleaned. A basket is ordinarily used for the straining element. Housing lids are usually held in place with swing bolts and maintain pressure in the systems with O-rings or gaskets. As pipe diameters increase the lids become heavier and manufacturers will often provide a hinge or davit arrangement to support the lid when opened. Ports for pressure gages can be provided so that pressure-drop monitoring serves as a maintenance indicator.                                                                               Duplex strainers use dual straining elements and valves to allow the elements to be cleaned without blocking out the strainer, ensuring continuous straining. Valves are typically ball, plug, or butterfly style. In some designs, the valves are synchronized so as one opens the other one closes.

Y-type strainers have a shape that resembles the letter Y. They are suitable for gas or liquid lines that are under pressure and have a low number of solids that need to be filtered out. They do not require frequent cleaning because of their design.

Temporary or start-up strainers are only used for a short time when new piping systems are being installed or after existing systems have been repaired.