Using the two-pressure technique, humidity is
generated by fully saturating gas at a known temperature and pressure,
then reducing the pressure to a lower value (typically ambient) at the
same temperature. The humidity produced by this technique is determined
solely from measurements of temperature and pressure, and does not rely
on measurement of the water vapour content.
With chamber temperatures up to 85°C and flow
rates to 150 standard liters per minute, the G9 boasts the highest
temperature, highest flow rate capability of any commercially available
two-pressure humidity generator.
All equations programmed into the computer
control system are high accuracy, internationally accepted formulations
for vapor pressure, enhancement factor, relative humidity, dew point,
frost point, ppm and others. Accuracy of the system relies completely on
the accuracy of the temperature and pressure measurements.
Unlike other two-pressure systems, use of cooling
water with the G9 is optional. If available, it can be connected and
will work to provide cooling of the refrigeration system. If not
available, the system reverts automatically to an air-cooled