Intro to Millwright Practice Exam 2025 - Free Millwright Skills Practice Questions and Study Guide

The acceptable range for fuel gauge pressure on an oxygen-mixing valve on a torch head is critical for ensuring safe and effective operation of the torch. The selected range of 5 to 7 pounds is correct because it balances the need for sufficient pressure to mix fuel and oxygen effectively without exceeding safety limits.

At this pressure range, the torch will achieve optimal combustion characteristics, allowing for better flame control and efficiency. Operating within this range helps to prevent issues that can arise from too low of a pressure, such as an inadequate flame that is not hot enough for certain applications, as well as the risks associated with higher pressures, which could lead to unsafe operating conditions or damage to the equipment.

Maintaining fuel gauge pressure within this specified range ensures that the mixing valve operates correctly, providing the right ratio of oxygen to fuel for combustion and minimizing the risk of backfire or flashback, which can be hazardous in welding and cutting operations.