Hygrometer
Calibrate hygrometers and RH/temperature sensors to ISO 17025 for environmental monitoring.
Standards
WMO-No. 8, ISO 29041, ISO/IEC 17025
Typical Interval
12 months
Uncertainty Range
±1–2% RH
What Is Hygrometer?
Hygrometers measure relative humidity (%RH) and temperature for cleanroom monitoring, document archives, and electronics manufacturing. Calibration uses a humidity generator providing reference %RH values traceable to NIMT.
Applicable Standards
Primary standards: WMO-No. 8, ISO 29041, ISO/IEC 17025
ISO/IEC 17025-accredited laboratories must maintain an unbroken traceability chain from the calibration result back to NIMT (Thailand's national metrology institute) or another internationally recognised NMI.
Typical Measurement Uncertainty
Expanded uncertainty is typically ±1–2% RH, depending on the measurement range, reference equipment used, and environmental conditions. The actual uncertainty will be stated on your calibration certificate.
Recommended Calibration Interval
A calibration interval of 12 months is generally recommended. The appropriate interval for your specific instrument depends on usage frequency, environmental exposure, and any applicable regulatory or customer requirements.
What Your Calibration Certificate Will Include
- Calibration results — instrument indication vs. reference value at each test point
- Error and expanded uncertainty (U) at k=2 (95% confidence level)
- Traceability chain to NIMT or a recognised NMI
- Environmental conditions during calibration (temperature, humidity)
- Calibration date, certificate number, and authorised signature
Find a Hygrometer Calibration Lab in Thailand
ThaiLabHub lists ISO 17025-accredited calibration laboratories across Thailand. Search our directory to find labs that offer hygrometer services, with scope details, location, and contact information.
For Labs: Manage Hygrometer Jobs with LabSync
LabSync helps Thai calibration laboratories manage jobs, issue traceable certificates, calculate GUM uncertainty budgets, and generate Thai tax reports (PP30 + WHT) — all in one system.
Frequently Asked Questions
Why is it important to calibrate a Hygrometer?+
Humidity and moisture control is critical for pharmaceuticals, food storage, and electronics manufacturing. A Hygrometer reading incorrectly by even 2% RH can invalidate environmental monitoring records. Calibration ensures accuracy to ±1–2% RH per WMO-No. 8, ISO 29041, ISO/IEC 17025.
How often should a Hygrometer be calibrated?+
Most Hygrometers should be calibrated every 12 months under normal operating conditions. High-use environments, harsh conditions (vibration, temperature extremes), or regulatory requirements (FDA, GMP, ISO 17025) may necessitate more frequent calibration. Always follow the manufacturer's recommended interval as a baseline and consult your lab's quality plan.
What does a Hygrometer calibration certificate show?+
A calibration certificate issued under ISO/IEC 17025 includes: the instrument identification (make, model, serial number), the reference standards used (with their own traceability chain), the measurement points tested, before/after correction values, the expanded measurement uncertainty (±1–2% RH), the environmental conditions during calibration, the calibration date and next-due date, and the signature of the authorized calibration engineer. This certificate is the evidence required for audits and accreditation.
Related Calibration Services
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