pressure carbon dioxide feed line 98 the ball valve 76 permits the pressure in pipe 70 to be reduced if it becomes too high as shown by gauge 80 coupled to pipe 70 finally a 2 inch pipe flange 82 supports a stub pipe 84 which passes through plates 42 52 and gasket 50 and supports a 2 inch ball valve 86 of a type well known in the art which controls the overall pressure in well 22 and permits the quick reduction of the pressure in the well of 160 to 400 psi to atmospheric pressure of 14 7 psi turning now to fig6 and 7 the manner of supplying the liquid gasses are shown the liquid nitrogen is maintained in a cryogenic tank 88 one such tank is sold by mve cryogenics type no ugl 160l and the liquid or gaseous nitrogen is released by opening valve 90 into high pressure hose 92 insulated with armflex insulation to prevent freezing one such hose is manufactured by western industries in stainless steel or braided metal another by goodyear tire and rubber company of double steel braided nitrite to the ball valve 64 to fig6 the liquid carbon dioxide is fed from cryogenic tank 94 via valve 92 high pressure hose 98 also insulated with armflex to ball valve.