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Safety Aspects of the G-01 Control Box
The G-01 Gas Membrane Control Box is made with Swagelok stainless steel fittings. They are rated by the manufacturer as follows.
Part | Pressure rating/psig |
¼” tubing | 7,500 |
1/16” tubing | 6,800 |
Black hose | 5,000 |
Quick-Connect couplings (when connected) [NB. These must be connected/disconnected only at atmospheric pressure.] | 4,000 |
Valves in the G-01 box | 6,000 & 5,000 |
Plug valve (on the line to the dac) | 3,000 |
These are the maximum working pressures recommended by Swagelok. They are not the bursting pressures: there is a large safety factor built into them according to US standards.
The maximum pressure that seems to be available from commercial gas cylinders is 3,000 psig, which is reduced to about 2,500 psig by a high pressure regulator. Thus, the rated presures for all components are well above the pressure at which the system will operate.
The gas membrane welds will also support this pressure so long as the membrane is properly located onto its matching pressure plate. In addition, the membrane is fully enclosed in the thick steel casing of the diamond anvil cell when the cell is assembled. Pressure should only ever be applied to the membrane when within a properly assembled cell.
The volume of the pressureised gas behind the membrane is only about 0.5 ml at 200 bar. Thus, the maximum gas volume at STP is under 100 ml. The rate at which gas can be delivered to the membrane is deliberately restricted by means of the attached capillary tubing to a maximum of 12 litres per second (at STP) under a pressure difference of 200 bar. Thus, the low volume of gas at the membrane, together with its total enclosure by the cell, ensures that there is no danger to an operator even should a leak develop in the membrane.
