An explosion occurred inside a mobile trailer containing five (5) gas-fueled clothing dryers at a fruit orchard and processing facility. The blast caused damage to the building, and the facilities manager, who was inside when it took place, received burns and contusions.
In 2019, the gas-fueled clothing dryers were installed and converted from natural gas to propane by unqualified individuals who left appliance gas valves connections loose. At that time, the appliances were not connected to a fuel source, and the trailer was stored for future use.
In 2024, a licensed contractor sent an uncertified plumber who finished connecting the appliances but did NOT check for leaks downstream of the shut-off valves, nor did they purge the gas piping of air.
When the facilities manager started the appliances, he did not immediately smell the odor of gas since the pipes had not been purged of air. The activation of the dryers created a source of ignition that likely ignited the air and fuel mixture to create the explosion.
The facility is a fruit orchard and processing facility that utilizes and houses seasonal migrant workers. Guidelines for seasonal housing for temporary workers in BC from the provinces Seasonal Agricultural Worker Program (SAWP) previously outlined that laundry facilities must include one machine for every 15 beds. As of October 2020, the requirement was increased to one washing/dryer machine for every ten occupants.
The facility obtained a used 24’ x 10’ ATCO mobile building to accommodate this requirement. The building was outfitted with a new electric water heater and five new Whirlpool stacker laundry washers/dryers connected to a standard black iron gas manifold. The building also contained a gas furnace that was not connected for use. Gas-fueled clothes dryers use the combustion of gas to heat the air used to dry the clothes. When the dryer is turned on for a heat cycle, the dryer drum and fan start immediately, and a hot surface ignitor is energized and begins to heat up. After a short time delay, after the ignitor has had enough time to heat up to a temperature that will ignite the gas, the gas valve opens to allow gas to flow to the burner to be ignited.
Installation and/or fuel conversion of gas appliances at a commercial facility is regulated work that must only be done by a person with a certificate of qualification, a recognized training credential, or under the direct on-site supervision of such person. A licensed contractor must not permit regulated work to be undertaken by persons under the control of the licensed contractor if they are not authorized to do so. It is the responsibility of the installer of a gas appliance to ensure before leaving the installation that the appliance, accessory, component, equipment, or piping and tubing they installed complies with the code requirements, and the person initially activating the appliance shall ensure that the appliance is in safe working order.
When a new piping or tubing system is installed, it shall be pressure tested before appliances are connected using an inert gas such as air before it is put into service. After the system has been pressure tested and appliances are installed, the remainder of the connected gas system and appliances, including any openings where gas can escape, shall be tested with either the test dial of a connected gas meter, a pressure gauge, a liquid solution, or leak detecting device.
Site observations
- A new copper gas line was connected between the propane cylinders and a black iron gas piping manifold.
- The data tags on all five of the appliances identified they were factory set for use with natural gas.
- The factory natural gas orifices were found in a conversion kit bag inside the building.
- Four of the appliances had gas conversion decals installed on the gas valve brackets that were only visible by removing the gas valves and one appliance had the conversion decal installed on the rear of the appliance that was visible from the rear of the appliance.
- None of the appliances had gas record labels supplied with the conversion kits applied that identify the date of conversion and the name and address of the organization making the conversion, who accepts the responsibility for the correctness of the conversion.
- Three of the five gas connection unions on the dryers that were behind closed access panels were loose.
- The mobile trailer had two damaged doors and the back wall behind the appliances had been pushed out from the force of the explosion.
Testing and measuring
Removal of the gas valves on all five appliances showed that they had all been converted from the factory settings and all of them had gas orifices and regulator caps for use with propane gas installed.
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