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- Gather equipment needed
- Leak valve
- Wrenches
- Nitrogen tubing line
- Relevant Hardware
- Ensure Nitrogen Dewar is full, and/or is at least more than half full.
- Close-off RGA section with its respective valve
- Leaving it under vacuum
- Close-off turbo/roughing pump section with respective valve
- Leaving it under vacuum
- Connect nitrogen line to inlet valve with pressure relief valve
- Allow approximately 5 minutes for system to be backfilled with nitrogen
- Remove blank from RGA cart hose, and replace with leak valve (Reference Figure 2)
- Ensure nitrogen is flowing through the system before starting this step!
- Ensure leak valve is tightly closed before placing onto hose
- Once leak valve is tightly sealed/connected to hose, let the system backfill with nitrogen again
- Make the connection to the leak valve at the end of the hose, making sure to tighten bolts all the way until metal to metal contact is made.
- Backfill for approx. 3-4 minutes
- Close, and then remove nitrogen line from current position and relocate to it respective spot on the leak valve
- Ensuring the leak valve is tightly closed, so no nitrogen is flowing into the system
- Turn on the roughing pump+turbo. (Do not open the valve to the RGA head YET!)
- Monitor the pressure at the roughing pump by observing the pressure at the Pirani gauge(s) as you throttle the valve(s) which open the roughing to the system.
- Pump for approx. 3-4 minutes, wait for pressure to reach a value below 10-7
- If turbo and pump are separately operated
- Once the cart and hose pressure are below 10-2 torr, switch on the turbo pump and wait for pressure to reach a value below 10-7.
- If pressure will not go this low, it is likely there is a leak somewhere on the cart or on the new connection
- Open the valve to the RGA head slowly while observing any pressure changes at the cold cathode.
- Pressure should equalize slowly. If pressure spikes, throttle the valve until the pressure equalizes. This would be an indication that the RGA was last vented (oops!).
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