When oxygen working pressure is being set on a regulator, the oxygen cutting lever must be depressed because

When oxygen working pressure is being set on a regulator, the oxygen cutting lever must be depressed because

• A. Acetylene flow is affected
• B. Cutting oxygen pressure is higher than the preheating flame pressure
• C. Preheat acetylene pressure is higher than the cutting oxygen pressure
• D. Cutting oxygen flow will lower the oxygen preheat pressure set on the regulator

Answer: (D)

The key idea is that the cutting lever on a cutting torch opens the cutting oxygen path, and that flow change affects the pressure in the oxygen line feeding the preheat side. When you depress the lever to set the oxygen working pressure, the regulator is delivering gas to the cutting circuit, which draws more flow and can cause the preheat-side pressure to drop. So the pressure you’re setting reflects the actual pressure that will be available when you start cutting, not the idle preheat pressure. This is why the correct answer states that cutting oxygen flow will lower the oxygen preheat pressure set on the regulator.

The key idea is that the cutting lever on a cutting torch opens the cutting oxygen path, and that flow change affects the pressure in the oxygen line feeding the preheat side. When you depress the lever to set the oxygen working pressure, the regulator is delivering gas to the cutting circuit, which draws more flow and can cause the preheat-side pressure to drop. So the pressure you’re setting reflects the actual pressure that will be available when you start cutting, not the idle preheat pressure. This is why the correct answer states that cutting oxygen flow will lower the oxygen preheat pressure set on the regulator.