Scope
Where this method applies
Use for fixed or portable air temperature and RH sensors used in plant environments.
Environment measurement · THC SOP
Air Temperature & RH Sensor Check
Document sensor placement, agreement, and operating context so temperature and relative-humidity records can be interpreted as measurements rather than assumed room truth.
Frequency
When to run it
Check after installation, relocation, suspected drift, exposure to condensation or contamination, and at a routine interval appropriate to the sensor and monitoring importance.
Preparation
Tools and preconditions
Required tools
- installed sensor
- trusted comparison sensor or calibration method
- location map
- record sheet
Before starting
- Avoid direct wetting or a placement that is known to be outside the intended measurement environment.
- Allow colocated sensors enough time to equilibrate before comparing readings.
Procedure
Run the method in order
Step 1
Document placement
Record sensor height, location relative to canopy or air sources, shielding, and any nearby heat or moisture source.
Record: Record location and placement description.
Step 2
Inspect
Check housing, vents, cables, batteries, and visible contamination or condensation.
Record: Record condition and maintenance.
Step 3
Compare
Colocate or otherwise compare against the defined reference method under a stable condition.
Record: Record sensor and reference temperature/RH values and time.
Step 4
Evaluate difference
Compare observed differences to the tolerance appropriate to the equipment and use case; do not silently offset data without a documented procedure.
Record: Record difference and pass/action decision.
Step 5
Return to service
Restore the sensor to its documented measurement location and confirm data logging resumes.
Record: Record completion and any configuration change.
Quality control
Verification checks
Sensor location is documented and repeatable.
Reference comparison has date/time and both values.
Any correction, replacement, or maintenance action is traceable.
Evidence record
Fields to preserve
- sensor ID
- location
- reference method
- temperature comparison
- RH comparison
- difference
- action
- operator
- notes
Interpretation boundary
Limitations
Relative humidity is temperature-dependent; a sensor in a different microclimate can disagree without either sensor being defective.
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