Take home message

Harvester fires can damage equipment, destroy crop and infrastructure and endanger life. With larger plantings of winter pulse crops in recent years driven by favourable pricing, our exposure to risk has been elevated. Steps to minimise harvester fire risk can be taken, so before harvest run through the checklist below to give yourself the best possible start.

Figure 1. Harvester fire

Checklist

There are a number of elements that add to the risk of fire on harvesting machinery. Most of these can be monitored, maintained, addressed and ultimately fires can largely be avoided.

According to Kondinin Group research, of the major causes of fires on harvesters, dust and trash build-up on the machine and bearing failures, together account for around half of harvester fires.

Mechanical failures are also implicated for one in 12 harvester fires.

While static electricity is regularly blamed for starting harvester fires, it is largely a fallacy. While static may attract additional fuel, potentially making fires worse, static discharge does not have sufficient energy to ignite crop dust.

Reducing harvester fires requires minimisation of the fuel and the ignition source. Research indicates harvesting winter pulse crops is up to five times more fire prone than wheat.

Fuel minimisation requires regular clean-downs of the machine, particularly in dusty crops and those that have suffered mould and disease. In extreme cases a blow-down every boxful may be required. Start on the front and move to the top working down from there.

Ensure concave doors seal well. One South Australian machinery dealer fits additional sealing in to prevent fine dust blowing out the concave doors and up onto the exhaust stream.

Bearing failure is the cause of one in four harvester fires. Buy an infra-red thermometer (around $50) and monitor bearing temperatures, keeping a log of discrepancies.

Some pulse crop plant material can ignite at temperatures as low as 130°C. While this can vary by seasonal conditions, there are plenty of components on a harvester that exceed this. In most cases much of the exhaust stream can exceed this.

Harvester exhaust system components can be insulated with ceramic coatings, moulded amorphous silica and insulating jackets to significantly reduce the area of high temperature. But each of these approaches has advantages and disadvantages.

Figure 2. Cracking of amorphous silica exhaust coating

Monitor the fire danger index (FDI) when harvesting (use a hand held weather meter). Cease harvesting if conditions deteriorate and the grass fire danger index (GFDI) approaches 35. Always have plenty of fire fighting equipment at hand in the paddock. I recommend 1000L of water, two fire extinguisher sets on the harvester; water (red) and an ABE - powder (white band around top of cylinder).

Get your harvesting team together  prior to harvest to plan out what will happen if there is a fire – how will you communicate, who will call the authorities, what tasks will each team member be responsible for.

Check your insurance policy covers all the components in your harvester, including the GPS equipment.

There is more research work to be conducted on minimising harvester fires including what influences crop ignition temperatures, understanding harvester heat signatures and how best to insulate the components above ignition temperatures. Fire suppression is also a topic of interest.

Figure 3. Harvester exhaust streams can easily exceed the ignition temperature of pulses.

Acknowledgements

Ben White and the late Dr Graeme Quick previously worked together to produce the GRDC Reducing Harvester Fire Risk: The Back Pocket Guide (DGQ00003) which can be accessed by following this link.

Contact details

Ben White
Agricultural Engineer
mobile: 0407 941 923
email: ben@bmwhite.com.au