EMC Learning Center

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EMC, or Equilibrium Moisture Content, is the point where the moisture inside your stored grain balances with the moisture in the surrounding air. At this equilibrium, grain neither gains nor loses moisture. This balance is driven by two things: temperature and relative humidity (RH) of the air moving through the grain.

In simple terms:

---If the air is drier than the grain, the grain will lose moisture. If the air is wetter, the grain will absorb moisture.
 

Knowing and controlling EMC is crucial for preserving grain quality, preventing spoilage, and maximizing profit.

When it comes to managing stored grain, many operators rely on ambient temperature or simple timers to run aeration fans. But the truth is, air conditions matter far more than just the clock. Here’s why EMC should be your decision-maker when operating aeration systems:

• Drying below safe storage moisture levels reduces spoilage risk.
   
• Prevents rewetting by avoiding high-RH air at the wrong times.
   

• Stops mold, insects, and mycotoxins from taking hold in high-moisture pockets.
   
• Maintains grain uniformity throughout the bin.
   

• Over-drying can mean unnecessary weight loss.
   
• EMC-based decisions help avoid excessive fan run-time, protecting yield and profits.
   

• Fans run only when the air will actually help—meaning fewer wasted hours and lower electricity costs.
   

• Well-preserved grain brings better grades, fewer dockages, and increased buyer confidence.

• 1. Know your goal: Are you trying to dry, cool, or recondition your grain?
   
• 2. Check the weather: Note the current air temperature and relative humidity.
   
• 3. Use the Fan Buddy EMC Calculator:
   
  • Enter crop type, temp, and humidity to see if conditions are good for running fans.
     
• 4. Or do it manually:
   
  • Use an EMC chart to find the air's EMC based on temperature and humidity.
     
  • If EMC < grain moisture, air will dry the grain.
     
  • If EMC > grain moisture, air may add moisture.
     
• 5. Run fans only when it helps:
   
  • Use favorable air to move grain toward your target moisture safely and efficiently.
     

A grower used EMC insights to recondition soybeans in a 60,000 bu bin using two 20 HP fans on 3-phase power.

Before EMC Use:

• Beans harvested at ~10% moisture
   
• No fan control — ran intermittently
   
• Delivered "dry" at 10% → shrink-adjusted sale weight: 58,500 bu
   

With EMC-Based Moisture Addition:

• Beans held with fans operated only when EMC > 12.5% (target: ~13%)
   
• Over 10 days, rehydrated ~0.75–1% moisture
   
• Final sale moisture: 12.8%
   
• Effective bu sold (using standard shrink tables): ~60,200 bu
   

Results:

• 🌱 ~1,700 extra bushels gained
   
• At $11.00/bu = $18,700 additional income
   
• Energy cost: same 29.84 kW x ~100 hours = 2,984 kWh → $358
   
• 💸 Net gain: $18,342 (after energy)
   

*Moisture was added safely with no spoilage risk thanks to EMC-based timing. Grain temperature stayed within spec, and dockage was avoided.

A grower typically ran fans 24/7 after harvest until mid-October to dry corn. Each fan is 20 HP, 3-phase.

Before Using EMC:

• Runtime: 20 days x 24 hrs = 480 hours
   
• Power usage: 2 fans × 20 HP × 0.746 kW/HP = 29.84 kW
   
• Energy used: 29.84 kW × 480 hrs = 14,323 kWh
   
• At $0.12/kWh → $1,719.
   

With EMC-Based Operation:

• Fans only ran when EMC was favorable (~45% of the time)
   
• Runtime: 216 hours
   
• Energy: 29.84 kW × 216 hrs = 6,443 kWh
   
• Cost: $773
   

Results:

• 💸 Saved $946 in energy costs
   
• ⏳ Avoided unnecessary wear on electric motor systems
   
• 🌽 Target moisture was reached faster, evenly, and without over-drying