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We are often asked technical questions about Vacuum Klein Flanges, so to try and answer some of the most frequently asked questions. Of course, if we have missed any or you would like further details please do contact us on +44 (0)1424 447726 or place your question in the comment box below.


1. Question – What are Vacuum Klein Flanges?

Answer– Vacuum Klein Flanges the word Klein comes from the German language meaning small therefore it is a small vacuum flange. The KF Vacuum Flanges were developed by a German company that required a Vacuum connection that could be used multiple times to connect Vacuum instruments, Vacuum scientific equipment, Vacuum pressure gauges and other Vacuum Equipment to a vacuum vessel. The Vacuum Klein flanges have a 15° angle on the back face that a tapered circular clamp fits over to pull them together forming a Vacuum Seal with the aid of an Elastomer O ring and metal carrier. The standard designation for this type of Vacuum flange is KF.

2. Question – What other designations are there for the KF Vacuum Flange?

Answer – QF – Quick Flange, DN Flange, NW Flange The KF designation has been adopted by ISO, DIN, and Pneurop. Standards

3. Question – How is the Vacuum-tight connection made?

Answer– Vacuum Klein Flanges are mated together using a circular carrier and o’ ring assembly fitted between two Vacuum Klein Flanges and sealed together using a Vacuum Klein Flanges quick clamp (see image below)

4. Question – What are the standard sizes for the Vacuum Klein Flanges

Answer – Vacuum Klein Flanges are supplied in the Standard sizes KF16, KF20, KF25, KF40, KF50. The dimensions for these sizes of Vacuum Klein Flanges are to the vacuum industry standard and are indicated by the nominal inner diameter in millimetres for Vacuum flanges 10mm through to 50 mm in diameter. Some sizes of Vacuum Klein Flanges have the same flange outer dimensions as the next larger Vacuum Klein Flanges and by using Vacuum Klein Flanges adaptive Centering rings they can be connected together (eg – KF10 to KF16, KF20 to KF25, KF32 to KF40,

5. Question – What Temperature can Vacuum Klein Flanges be used up to?

Answer – Vacuum Klein Flanges can be used up to a sustained temperature of between 150°C and 200°C with elastomer O rings.

6.Question – What Material are Vacuum Klein Flanges manufactured from?

Answer – Vacuum Klein Flanges are predominantly manufactured from Stainless Steel. However, the Vacuum Klein Flanges are also available in a variety of other materials and can be manufactured according to the customer requirements.

7. Question – Are there a range of standard Vacuum Fitting and Components manufactured with Vacuum Klein Flanges?

Answer – There is a complete range of standard Vacuum Components and Vacuum Fittings manufactured and stocked with Vacuum Klein Flanges.

8. Question- Can Vacuum Klein Flanges be supplied with electrical feedthroughs?

Answer – Vacuum Klein Flanges can be supplied with a variety of different electrical feedthroughs.

9. Question- Are View Ports available in Vacuum Klein Flanges?

Answer Vacuum Klein Flanges are available with a variety of different viewports We generally supply Vacuum Klein Flanges with Borosilicate windows. However, if a different window is required we can also supply this.

For any further information email us on [email protected] or call 01424 447726