Explosion in truck cabin in underground mine

Queensland Resources Safety & Health has released an incident report regarding a mine worker being seriously burned in an explosion in a truck cabin.

On 11 January 2021, a serious accident occurred while a mine worker was driving a truck in an underground mine. There was an explosion in the truck cabin causing serious burns to the worker’s face, hands and chest. Fortunately, the worker’s eyes were protected from the blast by safety glasses.

The force of the blast dislodged some of the windows of the truck’s cabin and these were blown clear of the truck. Figure 1 shows the deformation to the metal filter access panel for the air-conditioning (AC) system and Figure 2 shows a window lying where it was ejected by the blast.

Tyre explosion following a lightning strike

New cabin air standard ISO 23875

Whilst the investigation is still on-going, the findings of the investigation to date indicate that:

• the AC was charged with a refrigerant containing propane and isobutane (hydrocarbon) instead of compliance with the original equipment manufacturer (OEM) requirement which stipulates the use of R134a refrigerant
• the AC was not certified for the use of the hydrocarbon refrigerant
• personnel servicing and charging the AC did not hold Queensland Gas Work Licenses for working with hydrocarbon refrigerant
• the release of hydrocarbon refrigerant from the AC into the cab created an explosive atmosphere which was ignited by an unidentified source.

A similar incident occurred in 2014 when a drill operator in a coal mine suffered burns to the face, hands and torso in an explosion after hydrocarbon refrigerant leaked from the AC system and ignited.

Queensland Mines Inspectorate recommends to the Site Senior Executive must ensure that:

• they inspect all refrigeration plant and equipment including AC units on the mobile plant to verify compliance with OEM guidance with regards to refrigerant(s)
• any refrigeration plant and equipment charged with refrigerant(s) not specified by the OEM must be immediately quarantined from use
• if an alternate refrigerant is used, the refrigeration system must be inspected and certified for the use of that alternate refrigerant. In the case of hydrocarbon refrigerants, this is certified by the Petroleum and Gas Inspectorate
• any refrigerants may only be charged or drained by persons that are specifically licensed for those refrigerants.

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