Which type of fittings should be used in gas installations?

In gas installations, it is essential to use fittings that are specifically designed and approved for that purpose to ensure safety and compliance with building codes and regulations. Approved gas fittings and connectors are rigorously tested for their ability to withstand the pressures and conditions of gas systems. They are also designed to prevent leaks, which can lead to dangerous situations such as fire or explosion.

Using standard PVC fittings, while they may be suitable for other applications like water plumbing, is inappropriate for gas installations because PVC is not designed to handle the properties of natural gas or propane. Similarly, while iron and brass fittings can be used in various plumbing applications, they must be specifically rated and approved for gas use to ensure they can effectively maintain the integrity of the gas system without risking failure or leaks.

Therefore, the emphasis on using approved gas fittings and connectors is critical for safe and effective gas installations, making this the correct choice.