Strainer Design and Selection

Batu Valve strainers (filters) retain the solid particles carried by the medium and protect the valves, pumps and sensitive measuring instruments on the line.

Liquids, gases and steam passing through piping carry contamination with them: sludge, rust and scale in old systems; weld slag and gasket fragments in new ones. Installation of a strainer at the inlet of every fitting is therefore recommended.

Batu Valve strainer

Type code: BPT-FL

Connection: Flanged

Pressure: PN 16 · PN 25 · PN 40

Size: DN 15 – DN 200

Body: Cast iron · sphero · cast steel · stainless steel

Standard: TS 11494 / EN 558

Construction

A strainer consists of the body, cover, screen and drain plug. The screen is stainless steel (1.4301). The screen is cleaned by removing the blind plug on the cover.

Field of use: water, hot water, steam and non-flammable gases.

Selection of screen mesh size

Service	Mesh size
Pump suction protection	1.0 – 1.6 mm perforated plate
Control valve and flowmeter protection	0.5 – 0.8 mm
Steam lines	0.8 – 1.2 mm stainless steel wire mesh
Natural gas and air lines	0.25 – 0.5 mm

The screen surface area must be at least three times the pipe cross-section.

Installation direction and position

The direction arrow on the body must point in the direction of flow.
On horizontal lines the strainer is installed with the cover facing downwards or to the side.
On vertical lines the flow must be from top to bottom.

Monitoring of clogging

A pressure gauge is fitted at both the inlet and the outlet. The pressure difference across a clean screen is taken as the reference; the screen is cleaned when this difference doubles.

Strainer cleaning

The line is isolated, the pressure released and the strainer drained through the drain.
The cover is opened to the side.
The screen is washed against the direction of flow; it is not forced with a wire brush.
A torn or dented screen is replaced.
The gasket is inspected and the cover closed.

Cleaning intervals

Line	Interval
New line	First cleaning 24 hours after commissioning
Clean water	Inspection every 3 months, gasket once a year
Steam and condensate	Once a month
Medium with solid particles	Once a week

A screen of the same mesh size, a cover gasket and a drain plug gasket are held as spare parts.

Frequently asked questions

Where is a strainer installed?How often is a strainer cleaned?How is a clogged strainer identified?In which direction is a strainer installed?

It is installed at the inlet of the fitting to be protected.

It depends on the cleanliness of the line: inspection every 3 months for clean water, once a month for steam and condensate, once a week for media with solid particles. On a new line the first cleaning is carried out 24 hours after commissioning.

From the pressure difference between inlet and outlet. The screen is cleaned when the difference reaches twice the value for a clean screen.

The arrow on the body indicates the direction of flow. On a horizontal line the cover faces downwards or to the side; on a vertical line the flow must be from top to bottom.