During the verifier purity test, the ppm non-methane variation between the most remote outlet and the source gas must not exceed which level?

The correct response indicates that during the verifier purity test, the allowable variation in parts per million (ppm) of non-methane content between the most remote outlet and the source gas should not exceed 5 ppm. This limit is established to ensure that any gas delivered to medical outlets maintains a high purity standard, which is critical for patient safety and effective medical procedures.

Setting the variation at this level helps to ensure that the gas distribution system is functioning effectively without significant contamination or degradation of the gas quality as it travels from the source to the most distant outlet. A strict adherence to this standard mitigates the risk of adverse effects on patients, ensuring that the gases used for anesthesia and other medical applications are safe and reliable.

Other options present values that are either too low or too high for acceptable variation levels as outlined in NFPA 99 standards. This provides a framework for safe operational practices in environments that rely heavily on medical gases. Therefore, maintaining a 5 ppm variation is essential for adhering to compliance requirements and ensuring the integrity of the medical gas system.