Regulated humidity levels from 3-100% RH can be obtained using this controller in conjunction with the
humidification and
dehumidification accessories in the
COY Humidity Control Glove Box. The controller sits on the external glove box accessory shelf and a capacitive solid-state RH sensor is mounted in the glove box wall. As humidification is required, the controller activates the humidifier and air circulation pump. Should drying of the glove box atmosphere be required, glove box air is drawn through desiccant capsules.
Flow rates, sensor position, circulation, and orifice positions were all considered in the design to maximize control capabilities and humidity uniformity across the glove box interior. Since this is a closed loop circulation system, an inert gas environment can be maintained in the glove box while controlling the humidity.
To avoid accidental evacuation or pressurization of the glove box, relief valves are installed on the glove box wall.
Humidity sensors have traditionally been unstable, show large measurement hysteresis and dramatic changes in accuracy with small temperature changes. The design of this advanced sensor has addressed these shortcomings:
- Long term stability is better than 0.5% RH/year in normal conditions.
- Hysteresis is less than 0.5% RH over an excursion of 2O to 90 to 20% RH.
- No damage is caused by condensation on the sensing element.
- Temperature coefficient is minimal at +/- 0.04% RH/degC.
