Digital Measurement and Control of Mirror Temperature

The reflected light from the mirror is continuously measured by a high resolution A/D converter to detect the dew/frost layer thickness. This digital signal is then used in the control algorithm to properly drive the peltier element, establishing and maintaining the dew thickness at the equilibrium point. The mirror temperature is measured by a 100-ohm platinum resistance thermometer which is connected directly to a high accuracy, high precision A/D converter. The resistance of the thermometer is measured by the A/D converter and used, along with calibration coefficients, to computer mirror temperature.

Optimum Response Injection System (ORIS)

ORIS allows for faster measurements at low frost points, generally below about –60ºC. Typically, at these low frost point conditions, a chilled mirror hygrometer must cool the mirror to a value well below the actual frost point temperature in order to start the condensation process on the mirror. But due to the low water vapor content of the gas, it can take a very long time to establish a suitable frost layer on the mirror, then stabilize it at the proper equilibrium temperature. This can often take in excess of several hours. And the lower the frost point, the longer it takes.

Two-Pressure Two-Temperature Hybrid Humidity Generation Technique

Utilizing the uniquely combined benefits of the two-pressure and two-temperature techniques, humidity is generated by fully saturating gas at a known temperature and pressure, then reducing the pressure to a lower value (typically ambient) and cooling or warming to an alternate temperature.

Humidity produced by this hybrid technique is determined from measurements of the temperatures and pressures alone, and does not rely on measurement of the water vapor content of the gas.

With RH Systems’ hybrid humidity generation technique, the G2 is a true humidity reference instrument suitable for high accuracy calibration, product conditioning, and test applications.

Simple Application Integration

The G2 is supplied in a 19″ rack mountable format for integration within commercially available rack systems. A 19″ rack enclosures is available as an option. All electrical, fluid, and pneumatic connections are made at the back panel of the instrument. All fluid and pneumatic connections are via industry standard Swagelok fittings.