Boca Research None manual General procedures, Sample loading, Evacuation of the system

2 General procedures

2.1 Sample loading

At this point, the system will be open to the atmosphere, ensure that valve V2 is closed to prevent air condensation in the cold trap.

2.1.1 Loading Vessel 1

•Open the tap on the right-hand side of Vessel 1.

•Open tap A and valve V11.

•The liquid should be poured into the system very slowly to avoid liquid leaving the vessel via the side tap.

•When loading is complete, close the side tap, tap A and valve V11.

2.1.2 Loading Vessel 2

•Ensure tap E and valve V7 are closed.

•Remove the rubber septum on Vessel 2 and open tap E.

•Opening valve 12 allows the liquid to be poured directly into the glass bulb.

•When loading is complete, close tap E and valve V12. Replace the rubber septum carefully making sure not to place any strain on the metal-to-glass seals.

It is important to note that a small amount of liquid may remain in the system after sample loading is finished. Care must be taken to prevent this liquid reaching the pump.

2.2 Evacuation of the system

After loading the sample liquid, the system must be evacuated. However, air and possibly a small amount of liquid will be in the main body of the system. To avoid air condensation in the cold trap, the nitrogen dewar surrounding it should be removed and the glass U-tube allowed to warm-up.

•Close all the taps on Vessels 1, 2 and 3.

•Ensure that the pump is switched to roughing before opening valve V1. The pump can be switched to turbo if a high vacuum is required.

Once the system is evacuated, air must be removed from the vessel containing the sample to be cleaned. The system must be ‘let-up’ to atmospheric pressure using helium gas. This is achieved by first closing valve V1 and then opening valves V3 and V9. The pressure of gas in the system can be read from the baratron gauge.

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