Millwright Level 1 Practice Exam 2025 - Free Millwright Practice Questions and Study Guide

A hissing or squealing sound from a cutting torch typically indicates a flashback, which occurs when the flame travels back into the torch handle or hoses. This is a dangerous situation because it can lead to an uncontrolled reaction, resulting in fire or explosion. Flashback is usually caused by a mix of improper gas flows, inadequate equipment, or a failure to maintain proper safety protocols. Recognizing this sound as a warning is crucial, as it allows the operator to take immediate corrective action, such as shutting off the gases and inspecting the equipment for any damages or faults.

In contrast, backfire refers to a sudden and momentary flame that occurs at the tip of the torch and is usually less dangerous than a flashback. While a gas leak would cause a persistent sound, it typically has a different auditory signature associated with the escape of gas rather than the hissing or squealing indicative of a flashback. Improper pressure could affect the performance of the torch, but it does not specifically lead to the sounds described.