Common Temperature Alarm Code: What to Do When Fluctuations Exceed ±3°C?

We’ve seen it too many times—your medium-sized screw oil press suddenly triggers a temperature alarm, and the screen shows “±3°C deviation.” At first glance, it might seem minor—but in reality, this small variance can lead to significant losses in oil yield, protein degradation, and unstable emulsions.

Why ±3°C Matters More Than You Think

In our experience, even a 3°C fluctuation across the heating zones (typically set between 110–130°C for soybean or rapeseed) can reduce oil extraction efficiency by up to 7%. Why? Because inconsistent heat disrupts the natural moisture release from the raw material, leading to incomplete pressing and increased residual oil content. In one case study we documented, a plant in Brazil lost nearly $4,200/month due to repeated misdiagnoses of sensor faults when the real issue was poor insulation on the heating ring.

Real Mistake Alert: A technician in Indonesia once replaced a working PT100 sensor because they assumed it was faulty—only to find out later that the actual problem was a loose connection in the control module. This delay cost 3 days of production downtime.

How the System Actually Works (And Where It Fails)

Modern screw presses use segmented heating zones with feedback loops from multiple sensors placed at different points along the barrel. If one sensor reads +2°C while another reads -1°C, the controller may struggle to balance the system. We recommend checking three key areas first:

• Heating Ring Sealing: Poorly sealed rings cause uneven heat distribution—especially noticeable during high-humidity seasons.
• Sensor Calibration: Even new sensors drift over time; recalibration every 3 months is standard practice in EU-certified plants.
• Control Module Response Time: Some older PLCs take 30–60 seconds to adjust after detecting a change—a delay that amplifies fluctuations.

Our Quick Diagnostic Flowchart (No Tools Required)

Here’s what we teach our field engineers: Start with the simplest checks before moving to complex diagnostics.

1. Check if the alarm occurs consistently at the same stage—this suggests a mechanical or sensor issue.
2. If it's intermittent, inspect environmental conditions like ambient humidity or airflow around the machine.
3. Compare readings from two adjacent sensors—if one differs by more than ±1°C, replace or recalibrate it immediately.
4. Log data over 24 hours using your HMI system. If the average deviation stays below ±1°C, you’re likely safe to continue operations.

In lab tests conducted with both soybean and sunflower seeds, maintaining a stable ±1°C range improved oil clarity by 12% compared to ±5°C—measured via ASTM D1003 turbidity standards. That’s not just theory—it’s measurable impact on final product quality.