Thought i would expand on this with some order of magnitude leak rate guesses. For a standard small lab vacuum system with viton o-rings something like 10-7 mba

Thought i would expand on this with some order of magnitude leak rate guesses. For a standard small lab vacuum system with viton o-rings something like 10-7 mbarliters/sec (same as atmcc/sec) would be considered acceptable. Assuming the drive is pure helium at half pressure with this leak, the loss would be on the scale of 3 cc/year. The rate will decrease as the partial pressure decreases, but once this becomes significant im guessing the drive is already toast. I would also note that the helium will leak out before atmosphere leaks in. If the drives are well sealed they should fail due to lack of pressure causing head crash.