| 1030 | Fed Cricket 4 pellets. |
| 1040 | Did leak test. Background rate in hose: 5.8E-10 mbar*l/s. When IVC was opened, the rate dropped slightly to 4.5E-10 mbar*l/s. Didn't wait for it to stabilize, and closed IVC again. |
| 1340 | Connected helium leak checker to IGH vent. Helium leak rate in hose 4.2E-7 mbar l/s. Close valves 2A & 5A on IGH, and open vent speedivalve. Wait for leak rate to stabilise. |
| 1350 | Helium leak rate in mixing chamber lines leading to fridge 8.8E-7 mbar l/s. |
| 1450 | Conducted spray test on following flanges: condenser line speedivalve; welded joints at top of helium cold trap; between copper pipe and hose leading to helium cold trap; condenser port at back of IGH; N2 cold trap 1 & 2 in and out at back of IGH (4 total); vent at back of IGH; four KF10 flanges on N2 cold traps; two black caps on N2 cold traps; and welded joints on N2 cold traps. Valves 1, 2, 7, 8, 11A & 11B open on IGH. Dump isolated, manual valves closed. Vent speedivalve at back of IGH open. |
| | Helium leak rate fell gradually to 6.4E-7 mbar l/s during test. Liberally spraying the back of the IGH with helium before checking the flanges and joints on the N2 cold traps caused the leak rate to increase to 6.6E-7 mbar l/s. The leak rate then gradually fell to 5.9E-7 mbar l/s as the flanges and joints in the N2 cold traps were spray tested. Liberally spraying the back of the IGH with helium again at the end of the test caused the leak rate to increase gradually to 6.9E-7 mbar l/s. Leak rate is now at 6.0E-7 mbar l/s. |
| | This would indicate that there is a small leak somewhere in the IGH. It does not appear to be around the ports, and is likely to be from somewhere inside the IGH. However, the leak does not appear to be very large, and we have seen something similar before. It is doubtful that this is the cause of our now frequent blockages. |
| 1455 | Helium leak rate is now 5.6E-7 mbar l/s; rate of descent was gradual. We should consider opening up the IGH at some point in the future and conducting a thorough leak check. From what I've heard, the development of a leak within the IGH is not unusual. |
| | Close vent speedivalve and isolate leak checker. Start pumping on mixing chamber lines with He-4 pump. Turn off leak checker and wait for turbo to spin down. |
| 1748 | Finished 3 rounds of cold trap cleaning. |
