Large Rocker Operation
Prepare the Solution and Glass Liner
- Obtain the liner from the labeled drawer in the HPL. The liner can be checked out in advance. Be sure it is the correct size for the volume desired.
- Transfer the desired reactants into the liner being careful not to exceed the maximum volume specified.
- Place a metal wire around the neck of the liner to provide easy extraction of the liner from the pressure vessel.
Prepare the Pressure Vessel
- Ensure that the sealing surfaces on the head and base are clean.
- Wire brush them to remove any rust or other particles.
- Wipe them off after wire brushing.
- Lower the glass liner into the pressure vessel.
- Note ‘UP’ (or ‘TOP’) stamped on the outside of the pressure vessel.
- Place the liner so that the hole in the side is facing the same direction as the ‘UP’ (or ‘TOP’) stamped on the vessel. This will minimize leakage from the liner.
- Place the spring on top of the glass liner.
- Insert the thermocouple into the glass liner.
- Place the head on top of the base and spring, making sure to align the pins so that the ‘UP’ (or ‘TOP’) on the head is facing the same direction as the ‘UP’ (or ‘TOP’) on the base.
- Screw on the cap (with the screws recessed).
- After the cap is tightened all the way, back it off a ¼ of a turn to prevent it from seizing up during the reaction.
- Tighten down the cap bolts according to instruction on the 'Instructions for Installing Bomb Heads' page. (A diagram and instructions are also posted on the wall in the HPL.)
Load the Prepared Pressure Vessel into the Rocker
- Attach the pressure vessel to the pulley.
- Screw the two looped metal rods into the top of the cap.
- Insert a straight metal rod through the loops, ensuring that the washer and nut are attached on the outside of each of the loops.
- Attach the hook of the pulley to the horizontal metal rod.
- Using the pulley, insert the pressure vessel into the rocker with the stamped ‘UP’ (or ‘TOP’) facing up.
- Attach the two tubing connections to the thermocouple. Note: Counter torque must be applied when tightening and loosening the…
- Plug in the thermocouple.
Prepare the System
- Energize the required electrical circuits including the hydrogen monitor (circuit breaker #9)
- Using the piping diagram, verify the proper line-up to obtain the desired gases to your system. Always check valves in the SHUT (clockwise) direction only.
- With the regulators turned counterclockwise, pressurize the gas cylinders you require and adjust to the desired pressure.
Purge/Pressurize the System
- Shut the cell door.
- Note that pressurizing and venting should be done slowly (~20 psi/sec) to minimize frothing and the subsequent loss of reactants.
- Purge the system three times with nitrogen to evacuate the air, helping to reduce the risk of explosion. Monitor the system pressure to ensure acceptable pressure stability.
- Purge the system three times with hydrogen (or your desired gas).
- Pressurize the system to the desired starting pressure.
- Close the gas cylinders, back off the regulators, isolate the supply header, and vent the regulator load side using the ball valve above the regulators.
- For maximum pressure integrity, shut V19 if desired.
Program the Experiment Run
Program your desired temperature, ramp time, soak time, etc. Refer to Pressure and Temperature Plots for Large Rocker for specific instructions. Start the rocker, if desired.
Monitor the Experiment
NOTE: It is recommended that you monitor the system periodically until you are comfortable that the pressure is holding and that the temperature is correctly following its programmed profile. Since P1/P2 ≈ T1/T2, pressure will increase with temperature.
- After the experiment is finished, slowly vent off the hydrogen (or other gas used).
- Purge the system three times with nitrogen to expel the excess hydrogen.
- Disassemble the apparatus in the opposite order that you assembled it, only you need not worry about taking off the head bolts with a torque wrench.
- Be sure to clean up and put everything back in its proper place. If any of your solution spilled inside the pressure vessel, be sure to dispose of it properly and clean and dry the vessel with air.