Strainers are placed in-line with process piping to remove large solid contaminants from the flow.  Strainers can be cleaned and reused. Strainers 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.

Strainer Types

Strainer types can be basket or simplex basket, duplex basket, in-line, tee type, y-strainers, conical line or flat plate.  A simplex basket strainer is used where the line can be shut down for short periods to clean or change baskets. It becomes an integral part of the pipeline and all flow passes through it.  Duplex strainers remove damage causing particulate matter from the process media, and never have to be shut down for cleaning.  The line can run continuously. When one strainer basket becomes full, flow is switched to the other. The first basket is removed, cleaned and is ready for use again.  Some basket filters are 'temporary' and are intended for start-up use only.  In-line strainers are positioned with the basket parallel to the line of fluid flow.  They are often used in sanitary applications.  Tee type strainers are particularly adapted where basket replacement needs to be made quickly.  Y-strainers are devices for mechanically removing solids from flowing liquids or gases by means of a perforated or wire mesh straining element. They are used in pipelines to protect equipment such as pumps, meters, control valves, steam traps, and regulators.  Conical line strainers are used to protect fluid and gas handling equipment by removing debris during the start-up of a system. They are easily installed between large flange faces without modifying the surrounding pipe work and they are easily removed.  They are "temporary" strainers and are intended for start-up use only.  Flat plate strainers are inserted directly in the line of fluid flow.  They may also be used while held in the hand.  They are "temporary" strainers and are intended for start-up use only.

Strainers remove solids from a fluid line.  Some strainers may be available for specific types of media only.  Specific media types include liquids, gases, steam, and slurries.  Selection of strainers is dependent upon the pipe size of the process line or the nominal pipe size that can be accommodated by the strainer.  Strainers will have a maximum service design pressure that should be specified.  The screen opening is important to consider as well The standard most widely used in North America is ASTM E-11 standard (American Society for Testing Materials).  The opening is defined by a number (number 635 (20 µm) to number 3-1/2 (5.6 mm)) or is defined in inches (1/4 in. (6.3 mm) to 5 in. (125 mm)).  The standard used in Canada in the field of construction materials is ISO 3310-1 standard (International Standards Organization). The opening is defined in micrometers (20 µm to 37,500 µm).  Strainer selection also depends on process temperature; the full required range of ambient operating temperature.

Materials of Construction

Strainers can have a connection that is welded, flanged, threaded, clamped or brazed or soldered.  Materials of construction include bronze, cast iron, nickel alloy, carbon or alloy steel, stainless steel, titanium, polyvinyl chloride (PVC), polyethylene (PE), or polypropylene (PP, PPL).  Fiberglass strainers and rugged strainers made of reinforced plastics and composite materials are also commonly available. Features common to strainers include integral filters, magnetic inserts, steam jacketing, self-cleaning, and sanitary construction.