Vacuum flange

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A vacuum flange is a flange at 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 to allow various pieces of equipment to interact via physical connections and for vacuum maintenance, monitoring, and manipulation from outside a vacuum's chamber. Several flange standards exist with differences in ultimate attainable pressure, size, and ease of attachment.

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Vacuum flange types

Several vacuum flange standards exist, and the same flange types are called by different names by different manufacturers and standards organizations.

KF/QF

A KF-25 tee, o-ring, and clamp KF 25 Tee.jpg
A KF-25 tee, o-ring, and clamp

The ISO standard quick release flange is known by the names Quick Flange (QF) or Kleinflansch (KF, German which translates to "Small flange" in English). [1] The KF designation has been adopted by ISO, DIN, and Pneurop. KF flanges are made with a chamfered back surface that are attached with a circular clamp and an elastomeric o-ring (AS568 specification) that is mounted in a metal centering ring. Standard sizes are indicated by the nominal inner diameter in millimeters for flanges 10 through 50 mm in diameter. [2] Sizes 10, 20 and 32 are less common sizes (see Renard numbers). Some sizes share their flange dimensions with their respective larger neighbor and use the same clamp size. This means a DN10KF can mate to a DN16KF by using an adaptive centering ring. The same applies for DN20KF to DN25KF and DN32KF to DN40KF.

FlangeO-ring size
DN10KFAS-311
DN16KFAS-314
DN20KF
DN25KFAS-320
DN32KF
DN40KFAS-326
DN50KFAS-330

ISO

The ISO large flange standard is known as LF, LFB, MF or sometimes just ISO flange. As in KF-flanges, the flanges are joined by a centering ring and an elastomeric o-ring. An extra spring-loaded circular clamp is often used around the large-diameter o-rings to prevent them from rolling off from the centering ring during mounting.

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.

ISO large flanges are available in sizes from 63 to 500 mm nominal tube diameter: [2]

FlangeTube diameter (mm)
DN63LF63.5
DN100LF102
DN160LF160
DN200LF200
DN250LF254
DN320LF316
DN400LF400
DN500LF500

CF (Conflat)

A 2 3/4 CF (conflat) full nipple with blank flange and oxygen-free high thermal conductivity copper gasket Conflat Flange.jpg
A 2¾ CF (conflat) full nipple with blank flange and oxygen-free high thermal conductivity copper gasket
A 60 kV high-voltage electrical feedthrough on a 4 1/2 inch (or DN63) conflat flange 60kV Feedthrough.jpg
A 60 kV high-voltage electrical feedthrough on a 4½ inch (or DN63) conflat flange

CF (ConFlat) flanges use an oxygen-free high thermal conductivity copper gasket and knife-edge flange to achieve an ultrahigh vacuum seal. [3] The term "ConFlat" is a registered trademark of Varian, Inc., so "CF" is commonly used by other flange manufacturers. 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, allowing Conflat flanges operate down to 10−13 Torr (10−11 Pa) pressure. The knife edge is recessed in a groove in each flange. In addition to protecting the knife edge, the groove helps hold the gasket in place, which aligns the two flanges and also reduces gasket expansion during bake-out. [4] For stainless-steel conflat flanges, baking temperatures of 450 °C can be achieved; the temperature is limited by the choice of gasket material. CF flanges are sexless and interchangeable. In North America, flange sizes are given by flange outer diameter in inches, while in Europe and Asia, sizes are given by tube inner diameter in millimeters. Despite the different naming conventions, the actual flanges are the same.

European, Asian sizeNorth American size [inches]
DN101
DN161⅓ ("mini")
DN252⅛
DN40 (or DN35)2¾
DN503⅜
DN634½
DN754⅝
DN1006
DN1256¾
DN160 (or DN150)8
DN20010
DN25012
 13¼
 14
 16½

ConFlat gaskets were originally invented by William Wheeler and other engineers at Varian in an attempt to build a flange that would not leak after baking. [5]

Wheeler

A Wheeler flange is a large wire-seal flange often used on large vacuum chambers. [6]

American Standards Association (ASA)

A flange standard popularized in the United States is codified by the American National Standards Institute (ANSI), and is also sometimes named after the organization's previous name, the American Standards Association (ASA). [7] These flanges are elastomeric o-ring seal and can be used for both vacuum and pressure applications. Flange sizes are indicated by tube nominal inner diameter (ANSI naming convention) or by flange outer diameter in inches (ASA naming convention).

Nominal inner diameter/ANSIFlange outer diameter [inches]/ASA
14.25
1.55
26
37.5
49
611
813.5
1016

Vacuum gaskets

To achieve a vacuum seal, a gasket is required. An elastomeric o-ring gasket can be made of Buna rubber, viton fluoropolymer, silicone rubber or teflon. O-rings can be placed in a groove or may be used in combination with a centering ring or as a "captured" o-ring that is held in place by separate metal rings. Metal gaskets are used in ultra-high vacuum systems where the outgassing of the elastomer could be a significant gas load. A copper ring gasket is used with conflat flanges. Metal wire gaskets made of copper, gold or indium can be used.

Vacuum feedthrough

A vacuum feedthrough is a flange that contains a vacuum-tight electrical, physical or mechanical connection to the vacuum chamber. An electrical feedthrough allows voltages to be applied to components under vacuum, for example a filament or heater. An example of a physical feedthrough is a vacuum-tight connection for cooling water. A mechanical feedthrough is used for rotation and translation of components under vacuum. A wobble stick is a mechanical feedthrough device that can be used to pick up, move and otherwise manipulate objects in the vacuum chamber.

See also

Related Research Articles

A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength ; for easy attachment/transfer of contact force with another object ; or for stabilizing and guiding the movements of a machine or its parts. Flanges are often attached using bolts in the pattern of a bolt circle. The term "flange" is also used for a kind of tool used to form flanges.

<span class="mw-page-title-main">Gasket</span> Type of mechanical seal

A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly.

A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier (gate) out of the path of the fluid. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened. The gate faces can be parallel but are most commonly wedge-shaped.

<span class="mw-page-title-main">Vacuum chamber</span> Rigid enclosure from which all internal gases are pumped out

A vacuum chamber is a rigid enclosure from which air and other gases are removed by a vacuum pump. This results in a low-pressure environment within the chamber, commonly referred to as a vacuum. A vacuum environment allows researchers to conduct physical experiments or to test mechanical devices which must operate in outer space or for processes such as vacuum drying or vacuum coating. Chambers are typically made of metals which may or may not shield applied external magnetic fields depending on wall thickness, frequency, resistivity, and permeability of the material used. Only some materials are suitable for vacuum use.

<span class="mw-page-title-main">Drum (container)</span> Cylinderical shipping container used for shipping bulk cargo

A drum is a cylindrical shipping container used for shipping bulk cargo. Drums can be made of steel, dense paperboard, or plastic, and are generally used for the transportation and storage of liquids and powders. Drums are often stackable, and have dimensions designed for efficient warehouse and logistics use. This type of packaging is frequently certified for transporting dangerous goods. Proper shipment requires the drum to comply with all applicable regulations.

<span class="mw-page-title-main">O-ring</span> Mechanical, toroid gasket that seals an interface

An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, forming a seal at the interface.

<span class="mw-page-title-main">Hose coupling</span> Connector on the end of a hose

A hose coupling is a connector on the end of a hose to connect it with another hose or with a tap or a hose appliance, such as an irrigation sprinkler. It is usually made of steel, brass, stainless steel, aluminium or plastic.

<span class="mw-page-title-main">Pipe (fluid conveyance)</span> Tubular section or hollow cylinder

A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members.

<span class="mw-page-title-main">Face seal</span>

A face seal is a seal in which the sealing surfaces are normal to the axis of the seal. Face seals are typically used in static applications and are used to prevent leakage in the radial direction with respect to the axis of the seal. Face seals are often located in a groove or cavity on a flange. Face Seals are a category of products where there is no dynamic movement on the part of either the Seal or the hardware surface.

<span class="mw-page-title-main">Piping and plumbing fitting</span>

A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes.

<span class="mw-page-title-main">Ground glass joint</span> Used in laboratories to quickly and easily assemble apparatus from available parts

Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from interchangeable commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture. This is a large improvement compared with older methods of custom-made glassware, which was time-consuming and expensive, or the use of less chemical resistant and heat resistant corks or rubber bungs and glass tubes as joints, which took time to prepare as well.

A back-up ring is a rigid ring that holds an elastomeric seal or plastic connection to its designed shape and in its correct place. Back up rings are commonly used with O-rings, lip seals, and as reciprocating shaft seals. They are also used for piping connections joining two different materials - typically one flexible and one rigid.

<span class="mw-page-title-main">Groove (engineering)</span> Long and narrow indentation in a part/material, usually for other parts to fit into

In manufacturing or mechanical engineering a groove is a long and narrow indentation built into a material, generally for the purpose of allowing another material or part to move within the groove and be guided by it. Examples include:

  1. A canal cut in a hard material, usually metal. This canal can be round, oval or an arc in order to receive another component such as a boss, a tongue or a gasket. It can also be on the circumference of a dowel, a bolt, an axle or on the outside or inside of a tube or pipe etc. This canal may receive a circlip, an o-ring, or a gasket.
  2. A depression on the entire circumference of a cast or machined wheel, a pulley or sheave. This depression may receive a cable, a rope or a belt.
  3. A longitudinal channel formed in a hot rolled rail profile such as a grooved rail. This groove is for the flange on a train wheel.

FFKMs are perfluoroelastomeric compounds containing an even higher amount of fluorine than FKM fluoroelastomers.

ISO 2852Stainless steel clamp pipe couplings for the food industry was an international standard that defines a non-permanent sanitary food-grade piping interconnect method, commonly used in the food processing industry and with dairy farm equipment.

A Wills Ring or Cooper Ring is a form of all-metallic O-ring seal. They are used for extremely arduous service, such as sealing the head gasket of high performance piston engines.

<span class="mw-page-title-main">Parflange F37</span>

The Parflange F37 system is a technology from the hydraulic area of Parker-Hannifin, which allows a non welded flange connection of hydraulic tubes and pipes.

<span class="mw-page-title-main">Bonded seal</span>

A bonded seal is a type of washer used to provide a seal around a screw or bolt. Originally made by Dowty Group, they are also known as Dowty seals or Dowty washers. Now widely manufactured, they are available in a range of standard sizes and materials

<span class="mw-page-title-main">Scuba cylinder valve</span> Valve controlling flow of breathing gas into and out of a scuba cylinder

A scuba cylinder valve or pillar valve is a high pressure manually operated screw-down shut off valve fitted to the neck of a scuba cylinder to control breathing gas flow to and from the pressure vessel and to provide a connection with the scuba regulator or filling whip. Cylinder valves are usually machined from brass and finished with a protective and decorative layer of chrome plating. A metal or plastic dip tube or valve snorkel screwed into the bottom of the valve extends into the cylinder to reduce the risk of liquid or particulate contaminants in the cylinder getting into the gas passages when the cylinder is inverted, and blocking or jamming the regulator.

References

  1. ↑ "KF (QF) Flanges Technical Notes". Kurt J. Lesker Company. Retrieved 2007-09-02.
  2. 1 2 "ISO KF Flanges and Fittings" (PDF). Archived from the original (PDF) on 2007-09-29. Retrieved 2020-02-25.
  3. ↑ "CF Flanges Technical Notes" . Retrieved 2007-09-02.
  4. ↑ Daniel Bills (1996-10-06). "AVS Interview: 1996 Albert Nerken Award Recipient: William R. Wheeler". Archived from the original on 2013-08-08. Retrieved 2009-11-17.
  5. ↑ "AVS Interview: 1996 Albert Nerken Award Recipient: William R. Wheeler" . Retrieved 2009-11-17.
  6. ↑ US 3458221,Wheeler, William R.,"Metal vacuum joint",published 1969-07-29, assigned to Varian Associates
  7. ↑ "ASA Flanges Technical Notes" . Retrieved 2007-09-02.
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