Removing and Installing Copper Gaskets On Vacuum Chambers

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If you are new to UHV vacuum chambers and how to create a seal using copper gaskets when mounting optics, this blog post has some useful tips.

In many cases, installing the copper gaskets that are used to seal flanges on UHV vacuum chambers is as simple as placing the copper gasket in the knife edge recess. If the flange is facing down, then the gasket can be placed on the optics part being installed and the gasket will stay in place.

But in cases where the flange is perpendicular to the floor, the gasket will not stay in place on its own because the gravitational constant will prevent the gasket from staying in place. In other words, the gasket will fall.

There are a few ways to install a gasket onto the flange. But first, you need to make sure you’ve removed the old gasket properly.

Removing Gaskets

When you remove the old gaskets, you want to be very careful not to nick the knife edge on the flange when removing the old copper gasket because a nicked knife edge often results in a vacuum leak. And, nicked knife edges are difficult and sometimes very expensive to repair.

Usually the gaskets will come off easily with a minimum amount of force. For those gaskets that are pressed in tightly and very hard to remove, I have found that using a long-nosed vice grips locking pliers works quite well.

6" long nose Vice Grip needle nose pliers

You can adjust the gap on the pliers so that it firmly clamps down on the gasket, then simply bend the pliers so that the leverage will pop the gasket off the flange. It works every time and most importantly, it follows the number one rule of flanges – protect the knife edge. You can use a screwdriver to pry up the edge of the gasket, but if the screwdriver slips, you risk damaging the knife edge.

Pry up gasket

Two resources for removing gaskets:

Removal of metal UHV gaskets; Journal of Vacuum Science and Technology 12, 654 (1975) https://doi.org/10.1116/1.568642 https://avs.scitation.org/doi/abs/10.1116/1.568642?journalCode=jvs

A UHV-Gasket Removal Tool; Published March 1, 1983 https://www.nist.gov/publications/uhv-gasket-removal-tool

Installing New Gaskets

Method 1: Gasket Clips

The first method is to use a gasket clip. Gasket clips hold the copper gasket to the flange via a spring action. They line up with the flange’s leak check groove and hold the gasket in an area that is just past the knife edge of the flange.

Gasket Clip

Here is a link to the gasket clips that Ideal Vac provides:

https://www.idealvac.com/Agilent-GC0275S-Conflat-Gasket-Clip-Set-Package-of-10/pp/P105418

Gasket clips work well most of the time. Sometimes they will not work due to geometry limitations with other nearby flanges or optics.

If you do not have gasket clips, there are some other ways to mount a copper gasket to a horizontal flange.

Method 2: Elongate the Gasket

The second method is to elongate the gasket. This works well for larger copper gaskets, such as those for 10-inch and 8-inch flanges. It works with smaller gaskets as well, but you will need to drop them from a higher distance from the floor.

For an 8-inch gasket, hold the gasket about 1 foot above the floor. Hard concrete floors work best. This technique will not work on carpet.

Hold the gasket

Drop the gasket on its edge and it will hit the floor and bounce back up. You need to catch it when it bounces back up. If you don’t catch it and it falls to the floor, that is OK. You will just need to clean the gasket off with some isopropanol or methanol.

It takes a little bit of practice to get the correct height from which you are dropping the gasket. But the general rule is that the smaller the gasket, the higher the height. I have used this technique on 10-inch to 4.5-inch gaskets with good results. 10-inch flange gaskets should be dropped from about 6 inches. 4.5-inch gaskets should be dropped from about 18 inches. 2.75-inch gaskets are more difficult as they are harder to deform than the larger gaskets.

When you insert the gasket into the flange, you need to press it into the knife edge recess. The slight elongation will act like a spring and the gasket will stay in place.

Method 3: Cellophane (Scotch) Tape

Which brings us to the third method for mounting copper gaskets – cellophane (Scotch) tape.

Scotch Tape

You can use Scotch tape to mount the gasket as long as the tape is just barely on the gasket. Since the tape is mounted outside the knife edge, then it is OK if any of the tape stays on the gasket because it will be on the air side of the knife edge.

The pictures below show the knife edge cuts on common gasket sizes. For most copper gaskets (2.75- to 10-inch flange sizes) the knife edge is approximately .100 inches from the outside edge of the gasket. For the very small 1.33” flange, it is .050 inches from the gasket’s outside edge.

Knife edges

The procedure is to place the tape to where it is barely on the gasket (outside the knife edge region) and then very lightly touch the flange. You can use 2 or 3 sections of tape as needed.

Tape on copper gasket
6 inch CF flange
Gasket with tape

Once you get the optics part mounted to the flange with just a few nuts or bolts to hold it in place, pull the tape straight up and away from the flange. Usually all of the tape will come out. But if any small piece of tape is left behind, it will not matter since it is on the air side of the knife edge and will not have an effect on the vacuum.

Rotate the flange slightly to make sure that the copper gasket is properly seated before you tighten the bolts.

And don’t forget that if you are up to air for awhile and need to cover a flange or optics component with aluminum foil, you should use a UHV foil such as All Foils. UHV foil does not have an oil coating on it like foil from the super market does.

https://www.allfoils.com/single-product/uhv-foil/

UHV aluminum foil

RBD Instruments provides copper gaskets for less that what most other vacuum supply companies charge. – https://rbdinstruments.com/phi/uhv-parts.html

New Ion Beam Profiler

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Idaho National Laboratory has development a new type of ion beam profiler that reconstructs the ion beam intensity in two dimensions with a single measurement device.

This technology is available for licensing.    More information can be found at this link –

Ion Beam Profiler

Companies interested in learning more about this licensing opportunity should contact Kala Majeti at td@inl.gov or by calling 248-877-8866

Argon Bottle Installation Procedure

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RBD Instruments provides a refill service for the 25cc Argon gas bottles that are used on PHI (Physical Electronics) 04-303 and 06-350 ion guns on X-ray Photo-electron and Auger Electron spectrometers.

This blog post will describe how to install the Argon bottle and pump out the small volume of air that is between the bottle valve and the leak valve.  That small volume of air needs to be pumped out in order to prevent contaminating the argon in the new bottle.

The RBD part number to refill your 25cc Argon gas bottle is Argon25ccRP.   We can provide you with an exchange bottle which you can install on your ion gun’s leak valve and then return your empty bottle to RBD.  We also provide new bottles that do not require an exchange (contact us for a special offer on new argon bottles that runs until the end of July).

Procedure:

  1. Make sure that the leak valve is closed (fully CW and the arm should be parallel with the valve body).
  2. Close the green valve on the bottle (turn fully CW).
  3. Remove the six cap head screws that seal the bottle to the leak valve.
  4. Remove the bottle.
  5. Make sure that the green valve on the new bottle is fully closed (CW).  It should be very tight.
  6. Use a new 1.33” copper gasket and install the new Argon bottle to the leak valve.  If the old copper gasket is stuck to the leak valve flange, use a needle nose pliers to remove the old gasket.  Do not use a small screwdriver as that can damage the knife edge.   Tighten the 6 cap head screws evenly.
  7. Next, we will pump out the small volume of air that is between the leak valve and the green valve on the gas bottle.  You could just slowly open the leak valve and bleed the air into the chamber over a period of a day or two, but this procedure will pump that volume out in just a few minutes.
  8. With the turbo pump ON, pump out the load lock.   You can do that with the AVC remote by pressing the Pump Intro button, or by manually opening V3 on the auto valve controller.  We will be using the turbo pump to pump out the chamber and so need to first pump out the load lock.
  9. With the load lock pumped out (let it pump for 5 minutes or more), turn the high voltage OFF on the ion pump controller.  If your system has a Boostivac you can set the HV switch from Run to Standby.
  10. Press the I/T 3 button on the DIGIII ion gauge controller.  That will turn the filament OFF but still leave the power to the DIGIII on.
  11. With the green valve on the argon bottle still closed, open the leak valve 2 turns CCW.  That will start to bleed air into the chamber.
  12. Manually open V1.  The turbo pump will now be pumping on the chamber.
  13. Fully open the leak valve by turning CCW another 4 to 6 turns.
  14. The turbo pump may spin down slightly. You should have 5 bars on the AVC remote after just a minute or two. Let the turbo pump on the chamber for about 5 minutes. 
  15. After 5 minutes, press the I/T 3 button on the AVC to turn the ion gauge back on.  You should be in the low 10-5 to mid-10-6 Torr range.
  16. Flash the TSP for 2 minutes.   Let the vacuum improve for a minute or two.
  17. Start the ion pump high voltage.  For a Boostivac, set the HV switch to Start, then to Run.    The ion pump should stay on and the vacuum should be improving rapidly.
  18. Manually close V1.  The turbo pump is now isolated from the vacuum chamber.
  19. Once you are in the low 10-8 Torr range, close the leak valve by turning it fully CW.  The arm should be parallel with the valve body.  Do not over tighten the leak valve.
  20. With the leak valve closed (fully CW), open the green valve on the argon bottle by turning it CCW 1 full turn.  You may need to use a pliers as these valves are closed very tightly once filled with argon.    When the green valve is open the small volume between the green valve and the leak valve will be charged with argon.
  21. Installation is complete.   The vacuum will continue to improve and in 24 hours or so should be fully recovered to where the vacuum was prior to installing the new argon bottle.   Even the small amount of air that was bled into the chamber has enough water vapor to degrade the chamber vacuum.
  • 25cc-argon-bottle
  • Boostivac in standby
  • Boostivac monitor HV
  • Digitel 500 ion pump control
  • Flash TSP
  • Green valve on argon bottle
  • Leak valve fully closed
  • Leak valve fully open
  • New 25cc argon bottle