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The term UHV (ultrahigh vacuum) denotes the pressure range < 10-7 mbar. In order to attain and maintain such low pressures, the degassing rate of the entire apparatus must be extremely low. This can only be achieved by UHV capable materials and degassing of the entire apparatus over a longer period of time at temperatures of about 300 °C. If the ultimate pressure provided by the vacuum pump used is sufficiently low, the ultimate pressure attained in the vacuum system depends on the desorption rate of the chamber walls.
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For the reasons outlined above Trinos Vakuum-Systeme GmbH uses exclusively high quality steel materials complying with standard 1.4306 (304L). All components are welded from the inside in line with vacuum requirements or if the geometry does not permit, the components are welded through so as to avoid virtual leaks like cracks and pocket holes. Professional surface processing and cleaning guarantees very low degassing rates. Helium leak test with leak rates below 10-10 mbar × l/s are standard.
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Our UHV components are manufactured in accordance with ISO 3669 and Pneurop 6606 standards and in standard sizes of DN 16 to DN 250.
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The CF (ConFlat©) joint relies on flange profiles having cutting edges in connection with a metal gasket. During assembly, the cutting edges of the flanges are forced into the enclosed gasket, whereby the metal is displaced. This creeping process is restricted by the outer wall accepting the seal, so that very high pressures are attained in the boundary layer. Under these high pressures the sealing material flows plastically and equalises surface defects in the sealing surface whereby a metallic joint is created which is UHV-tight.
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Generally, OFHC (oxygen free high conductivity) copper is used as the gasket's material. Degassing of this material at temperatures up to 450 °C is easily possible a number of times, provided that - especially at greater diameters - heating and cooling cycles are not too fast. To avoid oxidization of the copper when exposed to air, the copper seals may also be silver plated. For testing, special gaskets made from Viton©, which can be re-used several times, may be used .
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It is important that during the assembly process the bolts on a CF joint are tightened evenly and crosswise so as to avoid any kind of bracing or warping. A radial recess at the flange serves, on the one hand to loosen the flange joint, and on the other hand helps to detect leaks since the helium test gas can be sprayed straight at the sealing surface. With components having two or more flanges, at least one of the flanges should be rotatable so that the components can be aligned as desired.
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| Nominal |
16 CF |
38 CF |
40 CF |
63 CF |
100 CF |
160 CF |
200 CF |
250 CF |
| ID [mm] |
16 |
35 |
38 |
63 |
100 |
150 |
200 |
250 |
| [inch] |
5/8" |
1 3/8" |
1 1/2" |
2 1/2" |
4" |
6" |
8" |
10" |
| OD [mm] |
34.0 |
69.9 |
69.9 |
113.5 |
152.0 |
202.5 |
253.0 |
306.0 |
| " [inch] |
1 1/3" |
2 3/4" |
2 3/4" |
4 1/2" |
6" |
8" |
10" |
12" |
| Height H [mm] |
7.2 |
13 |
13 |
17.5 |
20 |
22 |
24.5 |
26 |
| Setback R [mm] |
18.2 |
38.2 |
40 |
70.3 |
108.3 |
159.3 |
205.3 |
256.3 |
| Tube Dia. R [mm] |
18 x 1 |
38 x 1.5 |
40 x 1.5 |
70 x 2 |
108 x 2 |
159 x 2 |
205 x 2.5 |
256 x 3 |
| Bolt hole L [mm] |
27 |
58.7 |
58.7 |
92.15 |
130.25 |
181.0 |
231.8 |
284.0 |
| Screws |
6 x M4 |
6 x M6 |
6 x M6 |
8 x M8 |
16 x M8 |
20 x M8 |
24 x M8 |
32 x M8 |
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