NSW Deputy Coal Mine Practice Exam

Purging the bag is about making sure the sample inside truly represents the environment you’re trying to measure. By flushing the bag with clean gas before sealing it, you remove any residual air or previous sample that could contaminate the new sample and skew results. The other options aren’t about maintaining the bag’s integrity: inflating the bag to full capacity isn’t a standard integrity step and can risk overfilling or compromising the seal; not checking the barometer would ignore important pressure considerations that affect how the gas is stored and later interpreted; and performing a bump test on the gas monitor relates to instrument safety, not the bag’s integrity.