When considering transportation systems, our thoughts will normally turn to vehicles, such as lorries, locomotives, ships, and aircraft. In practice, even though it remains stationary throughout the operation, one of the most widely used vehicles to transport liquids and gasses is the pipeline. For example, a pipeline can be used to transfer oil for hundreds of kilometres from a well to a refinery. More commonly, they are used to transport water and, more often than not, a basket strainer will be included somewhere within the pipeline involved.
A number of different processes are carried out sequentially at a typical municipal water treatment plant, and one of these is fine filtration to remove microscopic solids. However, before the water can be introduced into a fine filtration system, it is necessary to remove any larger particles that may be present, which could otherwise result in it becoming clogged and non-functional. For this purpose, a form of basket strainer can be employed to act as a preliminary coarse filter, removing items, such as leaves, branches, and refuse present in the source water.
The suspended solids present in water, however, are not always this large and, in many situations, it is those particles that are just visible to the unaided eye that tend to lead to big problems if not removed. In addition to blocking any fine filtration media located within a pipeline, an accumulation of particulate matter can cause damage to other items of equipment commonly mounted within a pipeline. Once again, a basket strainer will invariably be the answer.
For example, in order to monitor the performance of filtration systems, pressure gauges are often installed on either side of them. This provides a means to measure the pressure drop between the incoming and filtered liquid, which gets bigger as the filter medium absorbs more solids until a point is reached when it must be cleaned or replaced. Unless the larger particles present in the liquid are removed, these gauges could be damaged by accumulated sediment, and so, give false readings. However, when locating a basket strainer upstream of the gauges, this risk will then be eliminated.
Made of perforated metal or mesh, as their name suggests, their design is basket-like. In order to function as intended, they can only be installed horizontally within a pipeline. While there is an alternative and more compact Y-shaped product that has no such limitation and is able to operate at higher pressures, it is the property known as the “‘open area ratio” or OAR, which is typically 6:1, but can be as much as 8:1. That is regarded as the main advantage of a basket strainer.