TL;DR
A hot spot in stored grain indicates microbiological activity and must be managed quickly to prevent spread. Aerate immediately, check moisture content, and move grain out of the affected zone.
What you might see
- temperature cable reading above 15 deg C above ambient in one zone
- musty or sour odor from the grain bin vent or sampling port
- grain caking or crusting visible at surface or at probe insertion
- insect activity near the bin aeration fans or vents
Likely causes
Grain stored above the safe moisture limit for the storage temperature
Moisture migration from temperature differential within the bin creating condensation zones
Foreign material (green weed seeds, chaff) with higher moisture content seeding a hot spot
Insect or mold activity generating metabolic heat in a localized zone
Required tools
- Grain moisture meter
- Grain probe (exterior use)
- Temperature cable display access
- Confined-space permit and monitoring equipment (if entry is required)
Safety first
- Grain bin entry requires a confined-space permit and continuous atmosphere monitoring. Grain engulfment is a fatal hazard.
- Never enter a bin with flowing grain or crusted grain that could collapse without a safety harness and attendant.
Procedure
- 1
Start all aeration fans on the affected bin immediately. Aeration cools and dries the grain and slows spoilage spread.[1]
- 2
Check the temperature cable readings across the full bin to determine if the hot spot is isolated or spreading.
- 3
Take a grain sample from near the hot spot using a grain probe and measure moisture content. Content above the safe storage limit for the temperature confirms moisture is the driver.[1]
- 4
If moisture is high, plan to move the affected grain to a dryer within 24 to 48 hours. Prolonged aeration alone will not stabilize grain above safe moisture limits.
Warning: Confined space entry into grain bins requires a confined-space permit, continuous atmosphere monitoring for CO2 and O2, and a standby attendant. Grain engulfment is fatal. Never enter without appropriate safety equipment. - 5
Do not enter the bin to probe near the hot spot unless all safety protocols are in place. Monitor from the exterior.
- 6
After stabilizing, have a grain quality specialist assess the grain in the hot-spot zone for discard or salvage.
- 7
Log the temperature cable readings for the 7 days preceding the hot spot to assess the rate of temperature rise for future monitoring thresholds.
Sources
Brock Grain Systems Brock M-Series Grain Silo / Storage Bin general technical documentation, Brock Grain Systems
Grain storage temperature monitoring and aeration management, general grain storage practice (general)
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