3pm local

CP4 = cryopump #4 at mid Y

John, Chandra

First, this morning we installed type K thermocouples along the exterior of the nitrogen exhaust pipe outside - one ~1 ft the exit of the building, one mid way down, one at the end of the SS exhaust line, and the last inserted inside the plastic flex tube (also the flow meter measures temperature).

We repeated yesterday's CP4 experiment by doubling LLCV (66% open) and allowing CP to overfill beyond 100% until LN2 came out the exhaust. I was physically at the exhaust line during the violent transition taking temp. measurements along exhaust. LN2 sputtered into plastic flex tube, so I quickly opened bypass exhaust valve and closed manual LN2 fill line on main Dewar (temporarily). It didn't help that during this chaos there were reverberations from an airplane or big truck in the distance that sounded like the entire arm coming up to air.

Temp measurements along the exhaust line (degC):

Time      TC1 (wall)     TC2 (mid)     TC3(end)     TC4 (flex tube)     TC5 (flow meter)
14:07     -27.4          5.8           21.9         22.8                -
14:43     -25.2          11.1          25.9         26.1                28.xx
14:55     -27.5          10.1          26.2         26.2                -
15:01*    -57.5          -49.3         -57.6        -193.8              -0.5
15:30     -23.1          13.7          15.6         16.3                19.7

*LN2 out the exhaust

Flow meter seems to be functioning still

John and I are considering installing a TC inside the end of the exhaust pipe at CP3 to use both this signal and the exhaust pressure to develop an automated fill every 2-3 days (no flow meter).