Laboratory thermo-hygrometers: why monitor temperature and humidity?

Essential for controlling the environment of chambers, cleanrooms and storage areas, the thermo-hygrometer measures temperature and relative humidity (RH) with the reliability labs expect. From microbiological incubators to climatic chambers, from refrigerator temperature mapping to pharmaceutical warehouse monitoring, it safeguards sample integrity and GMP/GDP compliance. Local display, secure data logger, alarms and dew-point calculation… our instruments combine Pt100/ thermistor probes with low-drift capacitive RH sensors for a traceable, reproducible measurement.

What are the different types of thermo-hygrometers and how to choose?

A thermo-hygrometer combines a temperature sensor (thermistor or Pt100) and an RH sensor, most often a polymer capacitive type (low power consumption, good stability). For reference calibrations, the chilled mirror (direct dew point) offers minimal uncertainty. Sling psychrometers remain useful for spot checks. Portable versions streamline field audits, wall-mounted models ensure continuous monitoring, and data loggers add memory, alarms and connectivity (USB, Ethernet, Wi-Fi, sometimes LoRaWAN).

Selection criteria: accuracy (±0.8 to ±2 %RH typical; ±0.1 to ±0.3 °C), stability and annual drift, response time, range (0–100 %RH; ?40 to +85 °C), calculations (dew point, wet-bulb), GxP and 21 CFR Part 11 data compliance, probe type (integral, remote high-temperature, miniaturised for vials), IP rating, ISO 17025/COFRAC calibration and traceability certificates. On durability: replaceable probes, rechargeable batteries, RoHS compliance and calibration procedures that extend service life.

See the comparison table below:

Type	Use	Advantages
Portable	Audits, chamber mapping	Versatile, fast response, lightweight
Wall-mounted	Continuous room/area monitoring	Stable, alarms, BMS integration
Data logger	Regulatory traceability	Memory, reports, 21 CFR Part 11
Chilled mirror (reference)	Calibration	High accuracy, low uncertainty

In which applications is a thermo-hygrometer used?

Controlling temperature/RH directly impacts quality, safety and compliance.

Life sciences: incubators, climate chambers, cell culture, biobanks.
Pharmaceuticals & biotech: ICH stability, GDP in warehouses, GMP production, ISO 14644 cleanrooms.
Food & beverage: HACCP, ripening, dry storage, cold rooms.
Environment: test stations, greenhouses and horticulture, indoor air quality.
Chemicals & cosmetics: in-process control, sensitive polymers, packaging.
Quality control: chamber mapping (refrigerators, freezers), HVAC validation.
Heritage & museums: conservation, prevention of mould and cracking.

Result: protected samples, stable processes, traceable documentation ready for audit.

The different types of thermo-hygrometers available

Thermo-hygrometers: frequently asked questions

How to choose a thermo-hygrometer’s accuracy?
Target ±1 %RH/±0.2 °C for critical QC; ±2 %RH suffices for ambient monitoring. Check the ISO/IEC 17025–traceable calibration uncertainty.

Where should the probe be placed for a representative reading?
Avoid walls, direct airflows and heat sources. Position at working height, in the centre of the area; use a radiation shield if needed.

How often to calibrate?
In regulated environments, every 6–12 months depending on drift/criticality. Use reference salts or an ISO/IEC 17025–accredited laboratory.

RH, dew point or wet-bulb: which to choose?
RH is universal; dew point is for condensation risk; wet-bulb is useful for comfort and certain HVAC processes.

Is a data logger mandatory in GxP?
Strongly recommended: secure time-stamping, an audit trail and 21 CFR Part 11–compliant reports streamline inspections.

How to limit condensation on the probe?
Stabilise temperature, use breathable filters and splash caps; prefer IP65 probes in humid environments.

Are probes replaceable?
On many models, yes. A replaceable or recalibratable sensor reduces downtime and extends instrument service life.