To reduce pressure to an acetylene regulator, the adjusting screw is turned:

• A. Counter-clockwise until the tension is off
• B. Clockwise to its limit
• C. Clockwise one full turn
• D. Clockwise one half turn

Answer: (A)

The adjusting screw on a regulator controls how much the internal spring is preloaded, which sets the downstream pressure. Turning it clockwise increases spring preload and raises the outlet pressure. Turning it counterclockwise reduces the preload, allowing the valve to open less and lowering the regulated pressure. So, to reduce the pressure to the acetylene regulator, you turn the adjusting screw counterclockwise until the spring tension is released, thereby lowering the output. After reaching the desired pressure, verify with the gauge and adjust as needed.