Refer to your study unit on WHMIS. Set supply pressure for cutting oxygen pressure at supply regulator to approximately 90 PSI Adjust Cutting Oxygen pressure on Hi/Low Preheat manifold regulator to the value shown in the chart above STEP #3 Using the manifold regulators, set low pre-heat fuel pressure to the lower of the two pressure values shown in chart above - preliminary setting The Pressure Adjusting Screw * Turning clockwise allows the gas to flow. Make sure regulator pressure adjustment screws are backed out! Oxygen and Acetylene Regulator Pressure Settings • Regulator pressure may vary with different torch styles and tip sizes. Extreme care must be taken with both tanks. Turning counterclockwise reduces or stops the gas flow. That tells me that the industry has **** near dummy-proofed this stuff! Yeah, James, when you think about it, you'd expect to see more horror stories in the news about oxy/acetylene disasters, huh? The Inlet Connections * Oxygen are right hand thread/Acetylene are left hand thread. The average pressure in an oxygen tank at room temperature (70°F / 21°C) is about 2200 PSI when full. * Oxygen and acetylene regulators* reduce pressure and control the flow of gases from the cylinders.The pressure in an oxygen cylinder can be as high as 2200 psi (15,169 kPa), which must be reduced to a working pressure of 1 to 25 psi (6.90 to 172.38 kPa). For 3/16" to 1/4" thick steel using a #0 cutting tip, your settings should be about 30 psi for oxygen, and about 4 psi for acetylene. Liquid acetone will quickly eat away the diaphragm of the acetylene regulator, allowing liquid acetone at full tank pressure to enter the hoses and torch. Make sure torch valves are closed! Stand away from front of regulator; Separately and slowly open the oxygen and acetylene cylinder valves; Adjust regulator p/a screws to tip pressure settings; Open/close torch valves separately and fine tune pressure settings on regulators The average pressure in an acetylene tank under the same conditions is about 250 PSI. At 12 psi for oxygen, you probably had trouble blowing through the edge of the material to get your cut started. A few years ago, I actually got a backfire started in the little "J" handle while trying to weld a butt joint in the corner of some 3/16 angle. The gases compressed in oxygen and acetylene cylinders are held at pressures too high for oxyacetylene welding. Keep free of oil, grease, & dirt! pressure to the hoses & torch. regulator!