Sensor Placement

Best Practices for Temperature Sensor Placement in Refrigerated Equipment

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Overview

Accurate temperature monitoring is critical for ensuring food safety and compliance within refrigerated environments such as cold rooms, freezers, and under-bench fridges. The purpose of a temperature sensor is to reflect, as closely as possible, the temperature of the food, rather than merely the surrounding air.

Proper placement of the sensor is therefore essential to achieving reliable readings that represent real product conditions while maintaining hygiene and operational practicality.

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1. General Principles of Sensor Placement

• Representative location:

  Sensors should be positioned inside the refrigerated chamber, near the area where food is typically stored. This ensures readings reflect actual food temperature rather than transient air fluctuations near the door or vents.

• Avoid air outlets and doors:

  Placing sensors near evaporators, fans, or doorways can lead to readings that are artificially cold or warm due to airflow patterns or frequent openings.

• Fixed and protected:

  The sensor should be mounted securely to prevent movement during normal use, cleaning, or restocking. It must not be positioned where drawers, shelves, or food containers can strike it.

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2. Practical Installation Considerations

• Ease of cleaning:

  The sensor must not obstruct cleaning operations. It should be located in an area that can be easily sanitized without requiring removal or risking damage.

• Non-intrusive installation:

  In cold rooms, sensors can be attached to internal wall surfaces using tapping screws, provided this does not breach insulation or sealing.

  In commercial under-bench fridges (e.g., Williams, Hobart), drilling into the unit is not recommended, as it can void warranties or compromise the system. Instead, use non-intrusive mounting methods such as cable ties or adhesive clips to secure the sensor to shelving, piping, or structural supports.

• Minimal user interaction:

  The sensor should not be touched, moved, or handled by kitchen staff during normal operations. Placement should minimize the chance of accidental disturbance.

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3. Hygiene and Contamination Control

• No food contact:

  The sensor must never be in direct contact with unpackaged or ready-to-eat food. It should not sit loosely in drawers or among food items.

• Avoid contamination zones:

  Position sensors away from areas where spills, condensation, or cross-contamination could occur.

  A fixed mount on a wall, grill, or pipe — near but not among food items — is generally preferred.

• Water exposure:

  While sensors used by MFC Safe are IP-rated, it is best practice to avoid placement in areas where water can pool or condense. Continuous water contact can cause corrosion or affect performance over time.

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4. Installation Durability

Sensor placement should be considered a semi-permanent installation, typically expected to remain in position for at least two years.

Before fixing, assess the site carefully to ensure the location:

• Reflects representative temperatures,

• Is not subject to mechanical impact or water pooling,

• Can remain undisturbed throughout the cleaning and maintenance cycle.

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5. Temperature Readings and Variances

Sensor vs. Fridge Display

It is normal and expected that the temperature reading from the MFC Safe sensor will differ from the temperature shown on the fridge’s display.

These readings are both correct within their context — they are simply measured from different physical locations.

• Different probe locations:

  The fridge’s internal temperature probe is typically positioned near the evaporator coil or airflow return, while the MFC sensor is positioned where food is stored. Airflow, door openings, and product load cause natural temperature gradients across the space.

• Accuracy and calibration:

  MFC Safe sensors are digitally calibrated and highly reliable. They either function correctly or fail outright. Instances of minor inaccuracies (1–2 °C deviation) are extremely rare.

  If a sensor shows incorrect readings, it is replaced rather than recalibrated in the field. Firmware updates are available to validate performance when needed.

• Different measurement objectives:

  • The fridge’s internal probe monitors air temperature for refrigeration control.

  • The MFC Safe sensor monitors food-proxy temperature for compliance and food safety assurance.

• Environmental variation:

  Air temperature distribution varies in all fridges and cold rooms. In larger or partially stocked rooms, airflow dynamics can lead to notable temperature differentials between zones. Multi-sensor setups can be used to assess and optimize these variations.

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6. Auditing and Compliance Considerations

• Deliberate placement in weak zones:

  Some hygiene managers or auditors request sensors be placed in vulnerable locations — such as near doors or high-traffic areas — to validate the unit’s ability to maintain safe temperatures under stress. This is acceptable for compliance testing but does not represent typical food temperatures.

• Balancing operational and audit needs:

  • Operational monitoring favors placement near stored food to reflect product temperature.

  • Compliance monitoring may favor a “worst-case” position for validation.

    A collaborative approach between engineering, hygiene management, and operations ensures both objectives are met.

• Environmental challenges:

  In hot and humid regions, refrigeration performance can vary significantly, particularly in older units or those operating near capacity. Additional engineering or more frequent monitoring may be required to ensure stability.

• Documenting placement rationale:

  The final sensor position and reasoning should always be recorded. If the sensor is positioned near a door or in another non-standard location for compliance reasons, documentation should note this to assist with future audits and analysis.

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7. Summary

Correct sensor placement balances technical accuracy, hygiene, and operational practicality.

Sensors should:

• Represent food temperature as closely as possible,

• Avoid interference with cleaning or handling,

• Be securely mounted and not immersed in water,

• Be placed with awareness of both compliance and operational goals, and

• Have their positioning rationale documented for future verification.

By following these guidelines, MFC Safe ensures reliable, auditable, and hygienic temperature monitoring across a wide range of refrigeration environments.

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