Fine and coarse strainer elements for demanding screening applications

Strainers are made for high flow volumes and low pressure loss. A strainer is fitted with a flow detector, preventing the barrier of the screen insert in front of the outlet and permitting contaminants to stay on the filter bottom. Here they can be easily eradicated from the below through an offset discharge port. The strainer is prepared for the connection of 2 presure gauges, permitting to control pressure loss occurring on the screen insert. Strainer is made with different screen insert types.

Perforated

A wide range of perforation sizes are available. For easy selection, a standard perforation size is recommended that is suitable for general application of each type of strainer. A general perforation size is specified to offer the excellent balance of open area ratio, hole arrangement and gauge thickness that results in minimal pressure drop. You should refer to every strainer’ specification sheet for standard perforation size.

Where possible, a 60 degree staggered round hole order is used for its excellent strength and large open area ratio. In small perforation sizes, a straight line is used, round hole pattern that allows for a large open area ratio while not compromising gauge thickness. Generally as the hole diameter becomes smaller and the open area ratio increases, gauge thickness gets thinner.

Wire mesh

Sintered Wire mesh strainer elements are recommended for finer straining applications. Plain weave mesh with large open area ratio and nominal flow resistance is commonly used. Other types of weaves used are plain Dutch and Twilled Dutch weave. Generally with perforated straining elements, standard mesh sizes are developed fit for standard service for every type of strainer. Unsupported wire mesh straining elements are only fit for strainers under 2 inches in size, made of 20 or 30 mesh and operating with low pressure applications. For large strainers, fine mesh sizes and higher pressure applications reinforced mesh lined screens should be used.

Wire Mesh Lined

In various cases, mesh strainer elements are strengthened with heavier gauge, perforated metal to offer additional support. Perforated metal backing 5/32 inch offers outstanding support without considerably reducing the open area ratio.

Considerable factors

Purpose:  If a strainer is used for protection rather than direct filtration, standard screens will suffice in various applications.

Service:  With services that need very durable screens like high pressure and temperature applications or services with high viscosities, perforated screens without mesh liners are preferred. If a mesh liner is needed to receive a specific level of filtration, a trapped mesh combination is used.

Filtration level: While choosing a perf or mesh combination, focus should be on to prevent overstraining. As per a general rule, the specific filtration level should not be lower than half of the size of particle to be eliminated. If very fine filtration is needed, the pressure drop through the strainer will increase quickly, feasibly causing damage to the screen.

Very fine mesh sizes such as of 5 micron and coarsed perforated plate of ½ inch dia offer innovative solutions.