Apart from those who are employed in water treatment plants, power stations, or the oil and gas industry, most people’s contact with pipes is limited to their domestic plumbing. While some consumers now choose to insert a special filter in the supply to their kitchen tap, its sole purpose is usually to improve the taste of drinking water that is already crystal clear and free of any solid particles large enough to be visible to the unaided eye. In an industrial pipeline, a strainer will often perform the task of removing those larger, visible particles.
There are several reasons why it may be necessary to ensure that the water or gas flowing through a pipe is free of particulate matter. A return to the kitchen scenario offers a convenient way to illustrate one of them. Frequently, a modern sink will have a metal device that acts to retain the water. Rotating the upper sealed layer of that device exposes a second layer containing narrow slots. The slots work much like the pipeline strainer, allowing water and tiny particles to pass through but retaining any solid bits large enough to block the sink’s U-bend.
However, on the industrial scene, blocked U-bends are not the concern. To control the flow of a contained liquid or gas requires installing various pieces of equipment at intervals along the pipe. Among the more obvious of these additions are pumps, to keep the pipe’s contents flowing, and measuring instruments to monitor the flow rate and pressure of those contents. Installing a pipeline strainer upstream offers a means to trap any particles that may be large enough to damage them or cause blockages in other components, such as valves and fine filtration equipment. For example, in a water treatment plant, preliminary straining of the source water to remove visible debris helps to improve the efficiency of sedimentation and filtration later in the processing.
Although the purpose of each is to act as a coarse filtration device, industries can choose between two types of pipeline strainers. One is known as a basket strainer while, based on its distinctive shape, the other is termed a Y-strainer. In addition to their differing designs, the two also display different performance characteristics. For example, the basket type is the better choice for flow streams with a high concentration of solids. The cheaper Y-shaped models are only suitable when contamination is minimal but can achieve higher pressures.
However, when it comes to flexibility, basket strainers are outclassed. Whereas one can install a Y-shaped pipeline strainer vertically or horizontally, the basket models are only compatible with horizontal systems.