Housing and handling
The housing and strainer element can usually withstand more than the strainer cover gasket between them. The gasket limits the temperature, it reacts to the medium, and it is stressed every time the strainer is opened. That is why we do not simply supply it with the strainer but select it – by medium, temperature and cleaning frequency.
Graphite with tanged steel insert
EPDM, Viton on request
DIN EN 1514-2
TA Luft · FDA · EU 1935/2004
A housing in 1.4571 withstands well over 300 °C and almost any medium found in plant engineering. An EPDM gasket does not. In practice, it is almost always the gasket that sets the permissible temperature range of a strainer. If the wrong material is chosen, it is also the first part to fail: it swells, hardens or is attacked by the medium.
Conversely, with the right gasket the limit shifts considerably. A pot type strainer with EPDM is designed for up to 120 °C, the same strainer with Viton for up to 150 °C – with an otherwise identical construction. That is why we ask about the medium and temperature before we specify the gasket, not afterwards.
The first two are standard equipment; we select the others to suit your medium.
Graphite layers on a stainless steel carrier sheet. Temperature-resistant far beyond the range in which elastomers give up, largely chemically neutral and reusable as long as the sealing face stays clean. In the TA Luft version also suitable for fuels and volatile media.
Elastomer for water, hot water, steam and aqueous solutions. Soft, and it seals even at low surface pressure – which makes it the right choice for closures that are tightened by hand. Designed for up to 120 °C on the pot type strainer; common up to 110 °C as a ring liner in butterfly valves.
Fluoroelastomer withstands higher temperatures and considerably more media: mineral oils, fuels, many acids and cleaning agents. On the pot type strainer, Viton raises the limit from 120 to 150 °C. Used in the TA Luft version for jet fuel.
For media that defeat elastomers – ammonium nitrate solution, strong acids, alkalis. As an O-ring or as expanded PTFE tape. The ePTFE version is approved for food contact to EU 1935/2004 and 10/2011/EU and is used in ancillary processes.
A wound strip of stainless steel 1.4541 with graphite filler, guided by an inner and an outer ring. It withstands high surface pressures and tolerates settling in the flange. It is used up to DN450 in pressure ratings PN40 and above.
Where pressures go even higher, the kammprofile gasket is an option: a metal core with fine serrations and soft facing layers, fitted in a machined groove in the sealing face.
Proven flat gaskets for general media, also available with FDA conformity. In strainer gaskets they form the carrier into which the wire mesh is inserted – face-to-face length to DIN 2690.
The following combinations are typical examples. They do not replace a resistance check for your application, but they show what has proven itself in practice.
| Type, medium or limit | Gasket | Note |
|---|---|---|
Standard by type | ||
Basket, simplex and duplex strainers | Graphite with tanged steel insert | Standard equipment |
| T-type strainer | Graphite with tanged steel insert | Standard equipment |
| Pot type strainer | EPDM | up to +120 °C |
| Strainer gasket | AFM 34 · Klingersil · graphite | Face-to-face length DIN 2690 |
Examples by medium | ||
| Fuels, tank farms | Graphite with tanged steel insert to TA Luft | with earthing lug |
| Jet A-1 | Viton to TA Luft | Example for simplex strainer |
| Ammonium nitrate solution | PTFE O-ring | Basket strainer in the chemical industry |
| Potassium hydroxide solution 30 % | top-chem 2000 | Basket strainer, e.g. DN100 PN40 |
| Oils | FKM | Basket strainer, e.g. DN150 |
| Edible oil | ePTFE to EU 1935/2004 | ancillary food processing |
| Nitrogen, inerting | AFM 34 with FDA conformity | T-type strainer, e.g. DN150 |
| Acids and electrolytes | FKM · PTFE · EPDM | depending on concentration |
Temperature | ||
| Pot type strainer with EPDM | up to +120 °C | Standard design |
| Pot type strainer with Viton | up to +150 °C | 30 K more with the same construction |
| EPDM ring liner in butterfly valves | up to +110 °C | e.g. changeover unit of a duplex strainer |
| Graphite with tanged steel insert | for the high range | Strainers up to +300 °C |
Whether a gasket material is compatible with a medium does not depend on the medium alone. Concentration, temperature, pressure and mode of operation also play a part: the same acid is harmless when diluted and cold, and a problem when concentrated and hot. A “material × medium” table would suggest a certainty it cannot provide. That is why we give typical combinations as examples and check your application individually – if in doubt, against the gasket manufacturer’s chemical resistance chart.
Yes. Before production starts, you receive the design drawing for approval – it also states the gasket material. Only once you have confirmed the drawing does the order go into production.
Of course. Drawings, specifications, parts lists or the data sheet of the previous strainer are the best basis. Our design engineers adopt your requirements and adapt them where manufacturing or the applicable code requires it – we agree any deviations with you in advance.
Graphite with tanged steel insert can be reused several times as long as the sealing face is clean and undamaged. Elastomer gaskets are better suited to frequent opening, but they age. With frequent cleaning, a stock of spare gaskets is part of the basic equipment – we include them on request.
Yes, ePTFE gaskets to EU 1935/2004 and 10/2011/EU are possible, as are fibre gaskets with FDA conformity. Please note: we filter ancillary media in food processes – such as steam, condensate or CIP caustic – not the food itself.
The German Technical Instructions on Air Quality Control (TA Luft) limit fugitive emissions at flanged joints. Gaskets in the TA Luft version are tested for this – they are regularly required for fuels and volatile media.
For high pressures and large flanges, where a flat gasket would settle. It compensates for movement in the flange and maintains the preload – used up to DN450 in PN40 and above.
Yes. Gasket replacement is one of the services we also carry out on strainers and filters from other manufacturers – as is the renewal of strainer elements.
All topics at a glance: Strainer options
Tell us the medium, concentration, temperature and how often the strainer is opened – this determines the material. For critical media, we check against the manufacturer’s chemical resistance chart.
