What is the consequence of not purging a gas line properly?

Not purging a gas line properly can lead to an increased risk of fire or explosion because improper purging may leave combustible gases in the line. When gas lines are installed or serviced, it's essential to remove any air or nitrogen that may have entered the system. If this is not done correctly, a potentially dangerous mixture of gas can remain. If there is an ignition source, it can ignite the remaining gas, resulting in hazardous outcomes, including fires or explosions.

The other options do not reflect the seriousness of the consequences. Improved efficiency and lower gas bills imply benefits from a proper purging process, while the notion of having no significant effect downplays the potential dangers involved. Understanding the risks associated with improper gas line purging highlights the critical nature of following safety protocols in gas technology work.