3-15
3.2.7.2 Example Instrument Set-Up
A chilled mirror hygrometer is to receive dew/frost point calibration at ambient temperature and
pressure conditions.
1) Connect the gas inlet side of the chilled mirror to the generator outlet fitting with polished
ID stainless steel tubing. The generator outlet is the Swagelok
®
fitting located on the
counter top farthest from the front of the generator. For best chilled mirror stability,
insulate this tube.
2) Allow the chilled mirror outlet to exhaust to atmosphere through a short section of
tubing. This helps to prevent upstream humidity permeation.
3) Connect the pressure transducer to mirror exhaust if other than atmospheric pressure.
Ensure that the transducer is plugged into the 3900. Otherwise, enter the mirror pressure
as the Test Pressure Setpoint.
4) If making relative humidity measurements, plug the Test Temperature probe into the
3900 and attach the probe to the mirror thermometer.
