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Vacuum Flange Types and Sizes

Main types of vacuum flanges that are fitted to the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other. Vacuum flanges are used for scientific and industrial applications.
EM Vacuum Assortment
Vacuum fittings: KF40‐40>25; KF25>19; KF40 for 19mm hose; VTR‐19 tubing; SS Vac bellow KF40; plus KF clamps rings

Vacuum Connection Parts and Fittings

Vacuum clamps, O‐rings, centring rings, blanking plates, hose adapters

They are widely used in the assorted vacuum systems and low‐voltage pipe systems, such as electronic, food machinery, the petrochemical industry, and medicine machinery.

Most vacuum fittings come with plastic protective caps which help protect the NW/KF flanges from scratches and dust.
NW/KF flanges

Vacuum flange types

KF / ISO‐K / CF

Klein Flange (DN/NW/KF ISO‐KF)

Klein Flange (KF/NW) fittings are the industry standard for vacuum components in the low and medium vacuum range and can be found on a variety of laboratory, production and test equipment.

"The ISO standard quick release flange is known by the names Quick Flange (QF), Klein Flange (KF) or NW, sometimes also as DN." ‐ Wikipedia.

KF fittings are an economical system of reusable interfacing stainless steel vacuum fittings and components. Each vacuum seal is made by compression of an O‐ring on a centring ring between mating flanges. The seal is made in seconds by finger‐closure of a wing nut on the all‐metal hinged swing clamp.

KF/NW style vacuum fittingMany pumps and vacuum gauges use the standard NW/KF flanges for easy integration. Test systems can be readily and quickly built utilising the large selection of NW/KF type components and can be easily modified for new tasks and applications. The NW/KF style vacuum components are available in the standard NW16 to NW50, with some components available in the smaller NW10.

The NW/KF system refers to the internal bore in mm:

NW/KF standard sizeInternal diameter (mm)External diameter (mm)
NW/KF101030
NW/KF161630
NW/KF252540
NW/KF404055
NW/KF505075

The terms NW, KF or QF all refer to the same standard quick release vacuum couplings.

Most standard NW/KF style quick release vacuum connections are made from a high quality grade 304 stainless steel. Stainless steel is a cleaner, stronger and more durable alternative to aluminium For specific applications, some vacuum components are also available in aluminium. The competitively priced ball valves offer an easy and quick way

ISO fittings (ISO‐K / ISO LF)

ISO fittings are joined by a centring ring and an elastomer o‐ring.

ISO Clamp"The ISO large flanges come in two varieties. The ISO‐K (or ISO LF) flanges are joined with double claw clamps which clamp to a circular groove on the tubing side of the flange. The ISO‐F (or ISO LFB) flanges have holes for attaching the two flanges with bolts. Two tubes with ISO‐K and ISO‐F flanges can be joined together by clamping the ISO‐K side with single claw clamps which are then bolted to the holes on the ISO‐F side." ‐ Wikipedia

ISO large flanges are available in sizes from 63 to 500mm nominal tube diameter.

ISO standard sizeTube diameter (mm)
DN63LF63.5
DN100LF102
DN160LF160
DN200LF200
DN250LF254
DN320LF316
DN400LF400
DN500LF500

Conflat fittings (CF / ISO‐F)

Conflat (CF) fittings use a copper gasket and knife‐edge flange to achieve an ultrahigh vacuum seal.

CF conflat hose adapter"Each face of the two mating CF flanges has a knife edge which cuts into the softer metal gasket, providing an extremely leak‐tight, metal‐to‐metal seal. Deformation of the metal gasket fills small defects in the flange..." ‐ Wikipedia
European, Asian sizeNorth American size [inches] 
DN101 
DN161? ("mini")1.33"
DN252? 
DN40 (or: DN35)2.75"
DN503? 
DN634.5"
DN754? 
DN10066.0"
DN125 
DN160 (or: DN150)88.0"
DN2001010.0"
DN25012 
 13¼ 
 14 
 16½ 

All of ProSciTech's NW/KF style vacuum connections conform to the international ISO 2861/I standard. KF series quick release flanges also comply with Standard GB4982‐85.
Other vacuum components, which may include three‐way types, blind plates, metal flexible corrugated pipes, callipers and bolts, heel blocks and holders, comply with the ISO Standard 9000:2000.
They are widely used in the assorted vacuum systems and low‐voltage pipe systems, such as electronic, food machinery, the petrochemical industry, and medicine machinery.
Our vacuum fittings come with plastic protective caps which help protect the NW/KF flanges from scratches and dust.

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