VectorFridgeShutDown260912

Unexpected shutdown of vector fridge on 26 09 2012

Magnet temperatures as I found them. Magnets are hot!

Fridge temperatures as I found them. Fridge is hot

IGH front panel as I found it. All valves are shut. Mixture is behind He3 pump and in He4 dump?!

IGH panel again. Notice P3=243! . Most likely mixture.

Pressure gauges as I found them. Probe>1500 mbar and IVC no Ident -> IVC is vented !? Gas in the OVC due to warming of the fridge. Still>1500. There is mixture in the fridge.

IGH front panel after recovery. After recovery pressures don't match previous values + He3 and He4 are mixed in the dumps. Fridge Crash Sept2012 Pressure Logs MG2-MG5.
See VectorFieldFridgeMixturePressureLog for details of the fridge dump pressures, but usually they are 990mB & 1153 mB, and we are now getting 985 & 919 mB.

So there is some mixture missing -- maybe this is in the IVC (-- AlexHamilton - 27 Sep 2012) ?

Switched off both compressors.

Waiting to warm up.

Oleh wrote that he pumped the IVC into the dumps and now the dumps pressures make sense: P6=1160 and P7=989. This is basically the same as the historical values, which says that the extra gas in the IVC may well have been mixture - but how on earth did it get there?

He Leak Detection

Hooked up Leak detector to Aux Port-1, to leak check the still lines and both condensing lines.

*done whilst waiting for fridge to warm up (Magnet temperatures ~ 242K).

*Note: Here we're used the leak detector's rotary pump as a substitute for pump S4.

Result of leak checking:

IVC is holding pressure so no leakage between IVC and fridge lines (still and both condensing lines).

Perhaps it is due to a blockage.

Cleaning Mixture via Fridge Attempt

The following attempts at cycling the mixture was repeated a couple of times, and the same result was obtained every time - inidicating a blockage in the condenser lines.

Blocked_condenser_lines.doc

Pressure Tests (5/8/12)

The following tests were conducted as per Giorgio's suggestion.

Fridge Logs of the Event

Plots of the fridge pressures & temperatures are provided below.

Crash occurred between 8:31am to 8:34am:

- Sudden heat load applied to all Plates of the fridge.

- Flow rate dropped from 177 to 0.

- Mixture was auto dumped in to P6 (He4 dumps rose from 18mbar to >500mbar)

- Mixture also auto dumped into IVC (P3 rose from ~0bar to 250mbar, MG2 and MG4 rose >1500mbar)

Magnet temperatures also increase.

Compressor Logs during that time period show no change - ie power was still on at that time and the compressors were in normal operation:

C:\Liquefier Logs\CompressorState 2012_09_24 1549.txt

Timestamp	Low side PSI	High side PSI	In water temp C	Out water temp C	He gas temp C	Oil temp C	Motor Amps	Diode temp K
08:31:18	082.7	264.5	070.5	087.8	134.6	081.7	15.0	NaN
08:36:26	090.0	273.9	070.9	088.5	135.0	082.4	15.0	NaN

C:\Liquefier Logs\CompressorState 2012_09_24 1551.txt

Timestamp	Low side PSI	High side PSI	In water temp C	Out water temp C	He gas temp C	Oil temp C	Motor Amps	Diode temp K
08:03:24	083.2	268.3	073.0	090.0	133.0	085.3	15.0	NaN
08:08:33	082.7	268.4	073.2	090.0	133.0	085.3	15.0	NaN

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