| | Status: One cycle of cryopumping mixture out of 3He pump completed. 3He Pump pressure at outlet reduced to 3.0 mbar as measured on G1. There is mixture in the Dump, Trap 2, the G1 volume, the IGH Manifold, the Vent volume, the Cryopump tubing, and the Cryopump. Cryopump is warm and open to G1, Dump and 3He pump are isolated, 3He pump is off. |
| 0850 | G1 (cryopump, warm) = 879.5 mbar, small variations overnight tracking with lab temperature. |
| 0855 | Lower cryopump into LHe Dewar. G1 (cryopump) quickly falls below 5 mbar. |
| 0900 | G1 (cryopump, cooling) = 2.3 mbar and pretty flat. A little below the last recorded 3He pump pressure. |
| 0900 | Open V13b, which opens 3He pump outlet to the cold cryopump. G1 rises slightly, 2.3→2.5 mbar |
| 0905 | Turn on 3He Pump. No noticeable increase in G1. |
| 0910 | Put Trap 2 into bath and fill with LN2. This may help pull a little bit more mixture out of the 3He Pump.
G1 falls, 2.5→1.8 mbar. |
| 0920 | G1 basically flat at 1.9 mbar. Close V13b, isolating 3He pump. Turn off 3He pump. |
| 0925 | Open V4, which opens Dump to Cryopump, then start pulling Cryopump out of LHe Dewar. Also remove Trap 2 from LN2 bath to let it warm up. |
| 0940 | Cryopump surface = 21.3 C (2 C lower than room temp), LN2 Trap 2 still frosty, = 14.0 C. G1 (dump+cryopump+trap 2) = 872.2 mbar and rising. |
| 0955 | LN2 Trap 2 = 17.0 C, cool to touch. G1 (dump+cryopump+trap 2) = 879.4 mbar. |
| 1040 | LN2 Trap 2 = 22.1 C, slightly cool to touch. G1 (dump+cryopump+trap 2) = 881.0 mbar, maybe still slowly increasing. |
| 1056 | P1 = 7.0 mbar. Open V6 to 100%. This way we can read pump inlet pressure at P1. After opening V6, P1 falls to 6.0 mbar. |
| 1100 | Turn on 3He pump. This pulls the few mbar of (probably) air from P1 to G2. P1 falls to 0.007 mbar, G2 rises to 1.2 mbar. |
| 1135 | Hook up a manifold of plumbing to the two t-intersections at both the output and the input of the 3He Pump. (The one on the inlet is on the IGH side of V6, which is one reason that we opened V6.) This manifold will allow us to bleed clean N2 into the pump before draining the oil, and also allow us to pump out the 3He pump with the scroll pump before operating it again. |
| 1145 | Let a little N2 gas into both sides of 3He pump. P1→50 mbar (which is probably too high to be correct on this gauge), G2 = 53 mbar (probably about right). |
| 1150 | Let more N2 into both sides of 3He pump. G2 → 840 mbar. (P1 = 80 mbar - normally I'd expect it to be pegged, but it probably reads differently when it's N2 instead of He.) |
| 1215 | Removing oil from LHe pump. Fill the shallow metal tray a few times - when it is partially full, put plug back in pump and empty try into a bucket. When oil is almost all out, turn on pump for a couple of seconds as per instructions in manual. Then open plug, more oil comes out. |
| 1220 | With pump outlet open to air, G2 reads 982 mbar. |
| 1225 | Repeat process of turning on pump a few seconds then drain some more a couple more times. (Note - I closed the speedivalve to the inlet tee, so that the inlet is isolated. So the first time we were pumping on 1 bar but the second two times it was low pressure.) Get a little bit more oil out. |
| 1230 | Finish draining oil. Replace plug. |
| 1330 | Measure the amount of oil removed: 3.30 L. Note that the manual says the oil fill min/max is 2.0/3.3 L. |
| 1345 | There is a partially full bottle of LVO 210 oil (about 0.3 L left in 5 L bottle), but the oil in it looks cloudy. The oil in a fresh bottle looks more clear. So we won't use the partial one - we'll throw that out. |
| 1355 | Start filling 3He pump with new LVO 210 oil. |
| 1520 | Disconnect the flange at the 3He Pump inlet to remove and clean the dirt trap. It looks pretty clean already, spray with methanol and wipe a little. A spot of dark oil was just inside the elbow that connects to the inlet. Wiped this off. |
| 1555 | We've put in about 2.1 L. The sight glass seems to have a floating plastic thing that rises with the oil level - the bottom of the patterned plastic thing is apparently the level. It's a bit above the bottom line right now which makes sense considering we're a little above the minimum amount (and there may have been a little left over that didn't drain out).
I get the impression that the oil was a bit overfull before. Since it ran well I'll err toward a high fill again but will avoid overfilling. |
| 1625 | About 2.6 L of oil has been added and sight glass is about 2/3 of the way up from the min line to the max line. We'll put a little more in, since it seemed to run pretty well before when it was overfull. But we'll stop short of the top line. |
| 1630 | About 2.75 L of oil has been added and sight glass is about 3/4 of the way up between min and max. We'll stop there. Replace fill plug. |
| 1640 | P1 at 3He Pump inlet currently reading 70.0 mbar. Pump out 3He pump inlet with scroll pump for 10-20 seconds. P1 falls to 34 mbar. Open 3He pump outlet to air. |
| 1645 | Turn on 3He Pump. Sounds pretty good, no whining or screeching. P1 falls quickly to 0.009 mbar. After 5 minutes it's down to 0.007 mbar. |
| 1650 | With pump running, oil level in sight glass is much lower, though still between the lines. It's about 20% of the way up. Turn off pump, see what it does. Rises up to about 30%. |
| 1705 | Add more oil until it's right at 50% on sight glass. This is a total of 3.0 L added. Turn pump on again. With pump on level is about 29%. |
| 1710 | Use scroll pump to pump out some of the pressure in the pump outlet. Pump G2 down from 982.8 mbar (when open to air) to about 160 mbar. |
| 1748 | Turn off 3He pump. |
