What indicates a fuel gas regulator is meant for left hand threads?

In welding and cutting applications, fuel gas regulators designed for left-hand threads often feature a V-notch cut around the nut. This distinctive cut serves as a visual identifier, allowing operators to quickly recognize that the thread direction is opposite to standard right-hand threads. This is crucial, as using the wrong fittings can lead to dangerous situations, including gas leaks or improper connections that compromise safety during oxyfuel cutting operations.

While other options might provide markings or indicators, they do not specifically convey the information needed to identify that the threads are left-handed. For instance, a circular cut could indicate other functions but lacks the specificity of the V-notch. A painted line or color code label might provide some form of identification, but V-notch cutting directly associates with the threading type, significantly reducing the potential for errors in gas connections. Understanding these indicators is vital for maintaining safe procedures in oxyfuel cutting.