Driver injured in explosion from AC system

The driver of a mining truck in Queensland has suffered serious burns in an explosion believed to be caused by an air conditioning system incorrectly charged with hydrocarbon refrigerant.

According to the Queensland Mines Inspectorate, the explosion occurred in the truck cabin while the vehicle was being driven in an underground mine. It caused serious burns to the driver’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. It also deformed the metal filter access panel for the air conditioning system (shown above).

Although the investigation is still ongoing, the findings so far indicate that the air conditioning system was charged with a refrigerant containing propane and isobutane (hydrocarbon) instead of R134a – as per the original equipment manufacturer’s (OEM) requirements. The system was not certified for the use of the hydrocarbon refrigerant.

Additionally, the personnel servicing and charging the air conditioning system did not hold Queensland Gas Work Licences for working with hydrocarbon refrigerant.

The release of hydrocarbon refrigerant from the AC system into the cab created an explosive atmosphere, which was ignited by an unidentified source.

The report notes that 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. The fatal Rochester Hotel explosion in 2014 was also found to be caused by an air conditioning system incorrectly charged with flammable refrigerant by unlicensed workers.

The latest incident is further confirmation that there are issues in Australia with air conditioning systems being incorrectly maintained, and the danger this poses.

The Queensland Mines Inspectorate has ordered the site senior executive to:

• Inspect all refrigeration plant and equipment including AC units on mobile plant to verify compliance with OEM guidance with regards to refrigerant(s)
• Immediately quarantine any refrigeration plant and equipment charged with refrigerant not specified by the OEM
• If an alternate refrigerant is used, inspect and certify the refrigeration system for the use of that refrigerant.

To read the Queensland Mines Inspectorate alert, click here.