A self-cleaning strainer is an application that is used to flush out debris by going through a complete cleaning cycle. Fluids that flow through these strainers, collect all the accumulated debris and are then flushed out. This system is a very practical solution for rural areas, due to the fact that it is very easy to maintain and does not require any manpower to operate.

These systems are usually used where fluids have to be cleaned, with a process called backwashing. Normally, high volume debris fluid like sewage, white paper from paper mills and earth are among the solid loading that has to be removed from a liquid pipeline or filtration system. Other liquids like gasoline, black liquor, lubricant oils, start fuel and chemicals can also be effectively strained with a self-cleaning strainer. An automatic self-cleaning strainer can often be more costly, but it does have a few advantages, including the following:

These units do not have to be cleaned frequently, which will save money on labour;

No damage can be done to the strainer, since the cleaning proses is automatic;

The strainer can be placed in a location where accessibility is difficult. This does not present a problem to automatic self-cleaning strainer units;

Because plugging is unpredictable due to variable loading rates, scheduling manual cleaning can be a problem if the unit is not automatic;

No personnel needed to clean these units. 

The straining process happens inside the self-cleaning strainer. During the straining process, several circular arrangements of elements are mounted to a removable tube sheet. Solid water enters through the inlet, passes through the tube sheet and flows from the inside to outside inside a chamber. Solids collected at the elements are then strained with water via a strainer outlet. Self-cleaning strainers are used in many industries. They are designed to be rugged, reliable and efficient. When they are used in a plant or process service water system, the liquids that are handled are not normally pre-screened.

With the backwashing process, an automatic strainer stays on-steam during the backwash cycle which is initiated by an adjustable interval timer or by a differential pressure. This will result in a continuous flow process. An automatic valve opens during the short backwash cycle and this then causes the backwash drive motor to energise and rotate the internal backwash assembly. Inside the tube sheet, a seal plate will move along the inlet as the backwash arm rotates. While a small amount of strained water is reversing, the elements are cleaned one by one in a sequence. This causes solids to be flushed through the backwash valve.