On average 7 percent of harvesters will start a fire in a given year.
Growers should develop a harvester fire plan to ensure they are prepared for the threat of fires igniting during harvest.
In the way that a bushfire survival plan is critical for all rural landowners during bushfire season, Kondinin Group general manager – research Ben White says growers should consider a harvester fire plan as a critical part of harvest.
“We know that on average, about 7 percent of harvesters will start a fire in a given year. If you add that up over only a few years, there’s a good chance that every grain grower will experience a harvester fire at some point,” he said.
“One in 10 of those fires will result in significant damage, which may sound like a low risk, but the potential losses from a fire are enormous. Harvester fires can burn through entire crops, cause serious burns or result in fatalities.
“With that on the line, every grower should have a plan, discussed with their whole team, on how to reduce the risk and respond to harvester fires.”
The ignition temperature of crops and residues varies between crops, with pulses, and lentils in particular, having the highest susceptibility. But it also varies from year to year, and researchers do not yet know what drives the ignition temperature.
This means that it is not possible to predict in advance whether a certain crop is susceptible to ignition, so all growers need to expect that a fire could occur at any time during harvest.
Develop a plan
Before harvest begins, Mr White recommends developing the harvester fire plan, whether it is a formal written document or just a conversation between the harvest team.
“The plan should include how the team plans to minimise the risk of fires, as well as what to do in the case of a fire starting. Just like bushfires, once the situation has started, it is too late to start thinking about how to react. A simple conversation can potentially save lives.”
A harvester fire plan should consider:
- Steps that will be taken to reduce the risk of the harvester catching fire, including maintenance and harvester hygiene.
- Monitoring weather conditions to ensure harvest stops when fire danger is high.
- Equipment needed to fight a fire, such as farm firefighter, extinguishers, water tanks, and where they will be in relation to the harvester.
- Communication during harvest – ensuring every team member knows the UHF channel and each other’s phone numbers and emergency contacts.
- Immediate action after a fire starts – including parking the harvester, fire-fighting, evacuation, communication between the team and calling emergency services.
- Triggers for evacuation for the team in the paddock and family members at home.
- Currency of farm insurance.
Mr White says growers should be cleaning their harvester down regularly.
“Harvester cleaning is the number one thing growers can do to reduce their risk of fires. They should be cleaned-down at least daily, but where there is a higher risk, for a dry or dusty crop or pulses, it would be sensible to clean more regularly. In extreme cases, the harvester may need to be blown-down as often as every bin. I know it’s a daunting prospect, but if that cleaning effort prevents a dangerous fire, it is worth it.”
The best tool for cleaning out harvesters is a large air compressor with a long hose and air-lance. Growers should ensure they inspect under guarded areas, where dust and chaff can build up and around hydraulic motors, where temperatures are high.
Along with material build-up, another key cause of harvester fires is machine maintenance and in particular hot bearings.
“Growers will generally do a full maintenance inspection before harvest for reliability reasons, which is also an excellent preparation for reducing harvester fire risk. Pay particular attention to bearings, the exhaust system and electrical components.
“It is also important to ensure the front receives a full inspection. Sometimes growers will focus on the engine, and not give enough attention to the front, because it’s detachable. But the front has a lot of moving parts and bearings which are prone to failure.”
Image 1: Heat shield jackets on hot components of the harvester, such as the exhaust shield shown, can potentially reduce fire risk, though there may be warranty implications. Source: Richard Konzag
During harvest, an infrared heat gun should be an essential item on the harvester.
“These guns cost less than $50 from any hardware or automotive store, so they’re a no-brainer. Measuring the bearing temperatures regularly means growers can detect when the temperature starts to rise and replace or repair bearings before they are a fire risk.”
There is some anecdotal evidence that shielding of hot areas, such as the shield shown in image 1, may reduce the risk of fires, though more research is needed in this area. Growers considering installing these modifications need to be aware of any potential warranty implications for new machines.
“Previous research by the late Dr Graeme Quick, an expert in harvester fire risk, indicated some crop dusts can have ignition temperatures of as low as 130 oC,” Mr White said.
“In these extreme scenarios, there will be many components of the harvester that are over 130 oC, so even if shielding is effective, it is certainly not a guaranteed solution. Growers still need to remain vigilant and keep on top of hygiene and maintenance.”
Fire danger index
Growers need to be prepared for the risk that a fire does ignite.
“Even when a grower is doing everything right, there’s still a chance that a harvester fire can start. It is important to be ready in case this happens,” Mr White said.
Growers can use the Grassland Fire Danger Index guide to assess the wind speed at which harvest must cease (a GFDI of 35), depending on the temperature and relative humidity.
Step 1: Read the temperature on the left hand side.
Step 2: Move across to the relative humidity.
Step 3: Read the wind speed at the intersection. In the worked example, the temperature is 35oC and the relative humidity is 10 percent so the wind speed limit is 26kph.
Source: CFS South Australia
The Grassland Fire Danger Index (GFDI) protocol provides growers with a resource to assess the risk posed by weather conditions during harvest. The GFDI is a function of temperature, humidity and wind speed, with a higher GFDI indicating that a fire will be more difficult to control. In South Australia, harvest must
cease at a GFDI of 35, and growers in other states are advised to follow the same limit (see “Harvesting in low-risk conditions”).
“As well as adhering to the GFDI, all growers should have an in-paddock firefighter and extinguishers. When parking the firefighter, ensure it is in an easy to access location. Growers should have a powder-type extinguisher in the cabin of their header for oil or electrical fires. I would recommend also having a water-type extinguisher which is best for putting out burning crops and residues.”
If growers have the capacity to do so and conditions permit, Mr White suggests that an option for fire-prone crops is to harvest at night with an observer, when temperatures are lower and fires are easier to spot.
A key part of the harvester fire plan should be communication during harvest and in the event of a fire.
“In many grain growing regions there can be poor mobile phone reception, so growers in these regions need to be wary of relying on their phone as a means of communication in an emergency,” Mr White said.
All workers should be briefed on the harvester fire plan before the operation commences, including aspects such as which UHF radio channel to use and phone numbers of key personnel.
Harvester fire reduction checklist
- Recognise the big four factors that contribute to fires: relative humidity, ambient temperature, wind and crop type and conditions. Stop harvest when the danger is extreme.
- Focus on service, maintenance and machine hygiene at harvest on the days more hazardous for fire. Follow systematic preparation and prevention procedures.
- Use every means possible to avoid the accumulation of flammable material on the manifold, turbocharger or the exhaust system. Be aware of side and tailwinds that can disrupt the radiator fan airblast that normally keeps the exhaust area clean.
- Be on the lookout for places where chaffing can occur, such as fuel lines, battery cables, wiring looms, tyres and drive belts.
- Avoid overloading electrical circuits. Do not replace a blown fuse with a higher amperage fuse. It is your only protection against wiring damage from shorts and overloading.
- Periodically check bearings around the harvester front and the machine. Use a hand-held digital heat-measuring gun for temperature diagnostics on bearings and brakes.
- Maintain fire extinguishers on the harvester and consider adding a water-type extinguisher for residue fires. Keep a well maintained fire fighting unit close-by to the harvesting operation ready to respond.
- Static will not start a fire but may contribute to dust accumulation. Drag chains or cables may help dissipate electrical charge but are not universally successful in all conditions. There are some machine mounted fire-suppression options on the market.
- If fitted, use the battery isolation switch when the harvester is parked. Use vermin deterrents in the cab and elsewhere, as vermin chew some types of electrical insulation.
- Observe the Grassland Fire Danger Index (GFDI) protocol on high fire risk days.
- Maintain two-way or mobile phone contact with base and others and establish a plan with the harvest team to respond to fires if one occurs..
*Source: GRDC Reducing Harvester Fire Risk: The Back Pocket Guide
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