Vacseal

Some leaks on the system can be temporarily sealed using Vacseal, a liquid vacuum leak sealant.

The group has successfully sealed leaks to carry us through to a maintenance period where we can replace the leaky part (on HVP metal-glass seam in 2021 and on HVP glass-heater flange in 2023).

To effectively seal a leak with Vacseal, we did the following: 0. If possible, run a leak check RGA scan to identify the exact location of the leak 1. Using a syringe, take in a small amount of the liquid Vacseal from the container 2. Slowly inject small amounts of the Vacseal to the location where the leak is. If running a leak test, you should start to see the intensity of the leak decrease as the Vacseal fills in the hole. Otherwise, you will notice the pressure of the chamber you are working on slowly decrease. 3. Continue injecting Vacseal until the leak is no longer detectable and the pressure continues to decrease. 4. Cure the Vacseal -- this can be done in a few different ways (per the manufacturer). For our HVP, we applied the Vacsel at Bravo's HVP low idle temperature, then increased the HVP to high idle for at least 24 hours. 5. Before proceeding with normal operation, we leak checked once more at high idle the following day.

Notes from the manufacturer:

• Vacseal can operate under vacuum from -200-450C

• Removal of Vacseal can be done with nearly any hydrocarbon solvent

• Some examples of curing conditions are given below:

  • 300° C for 30-40 minutes

  • 260° C for 1 hour

  • Room temperature: Very long cure time (days, maybe weeks)