What does the term "purge" refer to in gas systems?

In the context of gas systems, the term "purge" specifically refers to the process of removing air or any other unwanted substances from a gas conduit. This is a critical step to ensure safety and efficiency in gas systems, as the presence of air could lead to improper combustion or hazardous situations when the gas system is activated.

Purge procedures are implemented before the introduction of fuel gas to ensure that the system is fully ready for safe operation. By effectively clearing the line of air, it helps prevent ignition problems and ensures that gas can flow freely without obstruction or concern about the presence of combustibles. This process is particularly important when commissioning new systems or maintaining existing systems to reduce the risk of accidents.

Other options do not accurately describe the purging process. Refilling a gas conduit with natural gas, installing new piping, or measuring gas flow rates represent different operations and issues within gas systems, but they do not capture the essence of what purging entails.