Model 225-5230 & 225-5231 - Assmann Psychrometer
The 225-5230 Assmann Psychrometer utilizes two precision mercury thermometers with 3-point calibrations. A calibration certificate gives the correction required at each point. Corrected accuracy is better than ± 0.1°C. The double-tube thermometers are protected by a chrome-plated brass case. The thermometer bulbs are guarded by double-walled radiation shields thermally isolated from the main housing by a plastic bushing. Aspiration of the bulbs is accomplished by a spring-wound fan which will provide eight minutes of aspiration per winding.