Ops

Use Safety Goggles At All Times

Pumping Down the Line

  1. Check that all valves on line are closed, i.e. all switches on pneumatic valve card are in centre position. (OFF)
  2. Fit two clean and dry water/oil traps – note that the trap labelled "OIL" goes nearest pump, and switch on vacuum pump.
  3. Open bypass (green manual valve above oil trap) to pump down right-hand end of line.
  4. Open V6 (top right-hand switch on top left-hand bank of switches) and put LN2 on oil trap. Continue pumping down line.
  5. Put alcohol/dry ice on first two traps.
  6. Turn on Pirani. Open the rest of auto valves (V1-V5) and green manual valve on MS bottle on first trap and allow line to pump down to 0.5-1 Pa.
  7. Top up LN2 and alcohol traps.

Reaction Vessel (RV) Preparation

  1. Start with clean, dry reaction vessels and stirrer.
  2. Support RVs in an upright position.
  3. Place 6ml of phosphoric acid in each side arm and clip onto RV.
  4. Tare weigh each RV (containing acid) on balance. Record Tare weight.
  5. Remove caps, flush RVs for 5 minutes with zero air at ~ 1 l/min flow rate.
  6. Transfer approximately 100g of sample into each RV.
  7. Quickly replace caps on RVs and seawater sample bottle.
  8. Weigh RVs again and record mass of seawater.

Preparation for Sample Analysis

  1. Start "Sea Water Line Control" program, if not already running
    1. Double-click the "Seawater Line Control" icon to open LabVIEW (if not already open).
    2. Click on first arrow icon at top left of screen to RUN program.
  2. Ensure auto valves switches on the pneumatic valve card are in "CONNECT" position (slide switches UP). Valves 1-7 must be set in this position to allow computer control of the auto valves.
  3. Invert RV to tip acid into water sample and shake vigorously to mix for one minute.
  4. Attach RV to line. Ensure that magnetic stirrer is revolving smoothly.
  5. Place LN2 on CO2 trap under V4, top up LN2 or dry ice on other traps as required. Check again that all switches 1-7 are on "auto".

Sample Analysis Processing

  1. Click on START to begin processing.
  2. Process will now run automatically. You will be prompted to open sample bottle and put LN2 on manometer at the appropriate times.
  3. With LN2 still on manometer, record P2. This is the gauge "zero".
  4. Remove LN2 and apply water at room temperature. When pressure at P2 is stable, record "Gauge Pressure". Record also CJC temperature (room temperature).

Saving the Sample

Transfer sample to MS sample bottle. Check that MS sample bottle is pumped down. This is all done manually:

  1. LN2 onto MS sample bottle and top up LN2. Check that V1 and V3 are closed. Check Pirani is on the green scale.
  2. Open V2 on control board. Sample will transfer from manometer to sample bottle. Pirani will show the pressure change as CO2 transfers.
  3. Close V2 and sample bottle when Pirani gauge stabilises.
  4. Remove LN2 and sample bottle. Label the sample bottle and store in refrigerator.
  5. Attach new sample bottle and open V1 to clean out lab air from portion of line. When good vacuum, open sample bottle. Then open all valves 1-6 (all the way "down") and let line pump down to less than 1 Pa.

Seawater Line Shutdown

This is a manual procedure (and assumes the line is pumped down).

  1. Close V1, V2 and V3.
  2. Close sample bottle.
  3. Close V4.
  4. Take alcohol/dry ice off trap under V5. Wait. This allows water in the loop trap to condense in main water trap.
  5. Close V5. Remove alcohol from first trap.
  6. Turn pump off.
  7. Remove LN2 from oil trap.
  8. Open V7 (switch left-hand, bottom row, right-hand switch bank). This allows room air into first trap and oil trap via bypass (and allows removal of traps).
  9. Unscrew first trap and oil trap (remove o-rings and nylon bush) and place trap in oven to dry.
  10. Set all auto valves to "off" position.
  11. Switch Pirani mains off.

Briefly

  1. At startup, RHS of line will pump down to remove entrained air.
  2. CO2 trap will begin to cool.
    • Prompt to open RV valve
  3. CO2 trap will take a "bite" of sample and trap will continue to cool to –150 °C at the core.
    • At this point P1 should be typically 150mb depending on volume of sample.
  4. Trap will take "bites" of sample by cycling V3/V4 until P1 pressure is ~ 20 mb. V4 will then remain open, while V3 is pulsed.
  5. Sampling is finished when V4 closes. You will be prompted to put LN2 on manometer. The trap will continue to be cooled until you respond or LN2 runs out! After clicking OK the CO2 trap will then close and the heater will turn ON.
  6. CO2 sample will be transferred to manometer as soon as the transfer temperature is reached.
  7. End of run (prompt).