Pressure Regulators. (1) Check the regulator fittings for dirt and obstructions. Also check threads of cylinders and regulators for imperfections. (2) Connect the acetylene regulator to the acetylene regulator and the oxygen regulator to the oxygen cylinder. Use either a regulator wrench or a close fitting wrench and tighten the connecting nuts sufficiently to prevent leakage. (3) Check hose for burns, nicks, and bad fittings. (4) Connect the red hose to the acetylene regulator and the green hose to the oxygen regulator. Screw the connecting nuts tightly to insure leakproof seating. Note that the acetylene hose connection has left hand threads.