What must be done if a methane detector located at a vehicle fails in service?

When a methane detector at a vehicle fails, the correct procedure is to ensure the gas concentration is continuously monitored by a portable detector. This is essential for maintaining safety, as methane is a highly flammable gas that can pose serious risks in mining environments. Regular monitoring with a portable detector allows for real-time assessment of methane levels, helping to prevent potentially hazardous situations until the main detector can be repaired or replaced.

Using portable detectors provides an immediate and effective way to mitigate risks associated with the failure of the primary detection equipment. It ensures that workers remain safe and that any build-up of methane is promptly detected, thereby enabling timely evacuations or intervention measures.

The other options would not provide the necessary safety adjustments. For instance, removing the vehicle from site may not always be practical and does not directly address the need for ongoing monitoring. Similarly, prohibiting the use of portable detectors would impede safety protocols and create further risks. Relying on laboratory testing alone is insufficient in an operational context where immediate monitoring is required, as such testing typically lacks the real-time response needed in dynamic environments like mining.