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Edwards Fittings: Technical Data

Absolute vacuum services uk limited supplies, services, rebuilds and provides spares/parts for
Edwards Vacuum (formerly BOC Edwards)

CF flange names

There are many descriptions used to describe the same flange sides. Use the table below to cross-reference between common names.

In addition to the traditional aluminum hinged clamp. BOC Edwards also offers a range of coupling clamps manufactured from high technology polymer, offering important advantages for the vacuum system builder.

Compared to aluminum, the high flexural modulus and better strength-to- weight ratio has enabled BOC Edwards to design and manufacture clamps which are lighter and more compact than existing aluminum products. The CX4 crystalline aryl polymer clamps can be used at temperatures up to 120 degrees C and are unaffected by most common solvents.

These clamps are competitively priced and the high quality finish will enhance the appearance of any vacuum system. The range is available in swing and quick release hinged versions covering the following flange sires: NW10/16, 20/25, 25/32, 32/40 and 50. With BOC Edwards Co-seals, swing clamps are suitable for use in the pressure range 17 bar to 10(-7) mbar. Electrical continuity across the clamps is achieved by built-in earth strips.

Co-seal

The introduction of our Co-seal represented a major advance in the method of sealing NW and ISO flange connections. Discerning users appreciate the benefits of a seal design which eliminates crevices and trapped volumes. Our NW Co-seals with polymer carriers offer a more economical seal with even wider appeal.

A C0-seal has a split outer ring, or carrier, which retains a moulded elastomer sealing ring. When fitted, the inner face of the Co-seal is directly exposed to the vacuum system, eliminating any crevices or trapped volumes which can generate gas bursts and inhibit pump-down. Unlike the regular centering ring and 'O' ring, the NW Co-seal is fully restrained externally and is therefore suitable from 10(-8) mbar to 17 bar. Available with either nitrile or fluoroelastomer seals.

For ISO bolted flanges, cut-outs around the external circumference of the Co-seal are positioned so that the securing bolts centralise the Co-seal precisely. For ISO collar flanges, claw clamps also centralise the seal and are themselves spaced around the flange by the cut-outs in the Co-seal.

Centering rings in high technology polymer

We compliment our aluminum centering rings with a range manufactured from a high-tech polymer. These centering rings have a unique slotted design which prevents gas bursts The CM polymer can be used at temperatures up to 120 OC and is unaffected by most common solvents. The material has an outgassing rate of 6.6 x 10(-8) mbar | s (-1) cm (-2) which makes it suitable for use in most vacuum systems, whilst giving additional benefits in terms of lower weight and cost.

Operating pressure range (absolute)

C clamp and centering ring:
10^-7 mbar – 1 bar/ 14.35 psi

Stainless steel clamping ring and Co-seal:
10^-7 mbar – 17 bar/ 247 psi

Stainless steel clamp and metal seal:
10^-8 – 3 mbar / 44 psi

Stainless steel clamp and Co-seal (all sizes):
10^-7 mbar – 17 bar / 247 psi

Polymer and aluminum clamps and Co-seal:

NWIO to NW25:
10^-7 mbar – 17 bar / 247 psi

NW40 to NW50:
10-7 mbar – 10 bar / 145 psi

NW trapped 'O' ring :
10^-7 mbar – 1 bar / 145 psi

'O' ring and centering ring (vacuum use only):
1^-7 mbar – 1 bar / 14.5 psi

Bellows:
10^-7 mbar – 1 bar / 14.5 psi

Flexible pipelines:*
10^-7 mbar – 2 bar / 29 psi

Braided flexible pipelines: *
10-7 mbar – 10 bar / 145 psi

*Depends on size

Operating temperature

Polymer Co-seal:
-10 to 80 degrees C

Aluminum Co-seal and nitrile seal:
-10 to 100 degrees C

Aluminum Co-seal and fluoroelastomer seal:
-10 to 200 degrees C

Polymer centering ring and nitrile 'O' ring:
-10 to 100 degrees C

Polymer centering ring and fluoroelastomer seal:
-10 to 125 degrees C

Nitrile 'O' ring:
-10 to 100 degrees degrees C

Fluoroelastomer 'O' ring:
-10 to 100 degrees C

Polymer clamp Constant vacuum use:
-10 to 100 degrees C

Intermittent vacuum use:
-10 to 125 degrees C

Stainless steel clamping ring:
-10 to 125 degrees C

Aluminum clamping ring:
-10 to 200 degrees C

Stainless steel clamp:
-10 to 200 degrees C

Standards compliance

NW and ISO fittings:

Pneurop 6606 (1981)

ISO1609 (1986)

DIN28440, DIN 28404

ISO3669

CF fittings

Stainless steel equivalents

Chemical resistance

This information is provided as a general guide only. Further guidance should be sought with respect to specific chemicals and their applications

Edwards Fittings: Dimensions