The Michell Instruments Opti-Cal Humidity & Temperature Calibrator comprises a precision-controlled chamber that can house up to five or more humidity sensors, depending on their physical dimensions. Humidity and temperature within the chamber are closed-loop controlled and continuously monitored by an integral precision chilled mirror reference hygrometer, ensuring fundamental measurement accuracy.

The system works by time-proportioning the flows of dry and saturated air according to the pre-selected relative humidity value. Chamber temperature is controlled by a four-zone Peltier heat pump arrangement that delivers maximum stability and minimum temperature gradient across the working volume. The saturator assembly is easily filled via a distilled water reservoir at the front of the unit, while the accessible desiccator can be re-charged by heating when required—no other maintenance is necessary.

With a temperature range of 10 to 50°C (±0.1°C accuracy) and RH range of 10 to 90% (≤±1% RH accuracy in the 10-70% range), the Opti-Cal provides exceptional performance for sensor calibration. The instrument requires only a single-phase power supply for operation, with no other external services needed. UKAS accredited calibration is supplied as standard, providing immediate confidence in measurement traceability. This combination of integral reference standard, precise control, and large chamber volume makes the Opti-Cal ideal for on-site calibrations, laboratory use, and quality assurance applications where multiple sensors must be verified simultaneously.