PST Michell Instruments S8000 -100, User Manual, Page: 22 / 68

S8000 -100 User Manual
14 97606 Issue 1, June 2021
OPERATION
3 OPERATION
As supplied, the S8000 -100 is ready for operation and a set of default parameters has
been installed. This section describes both the general operation of the instrument and
the method of setting it up and changing the default parameters, should this become
necessary.
3.1 General Operational Information
While the instrument can physically operate in a flowing gas stream of between 500 and
1000 ml/min (1 and 2.1 scfh), Michell Instruments recommends operating at 750 ml/
min (1.6 scfh), which is the flow rate used during calibration. Operating at an alternative
rate could impact the instrument’s response time.
The sample inside the sensor is passed over a Peltier chilled, gold-plated mirror. The
instrument controls the mirror temperature to a point where a level of condensate is
maintained on the mirror surface. The temperature of the mirror is then measured as
the dew point.
The S8000 -100 is suitable for the measurement of moisture content in a wide variety
of clean, non-corrosive gases. It will not contaminate high-purity gases and is safe for
use in critical semi-conductor and fiber optic manufacturing applications.
3.1.1 Sample Flow Adjustment
• The sample flow is measured by the internal flow meter installed
into the sample line.
• The recommended flow setting is 750 ml/min (1.6 scfh).
• The sample flow can be adjusted by the installation of a valve in the
sample line. Ideally the valve should be installed downstream of the
sensor to avoid any influence of moisture ingress on the readings;
however, in this configuration care needs to be taken to ensure
the flow rates in the system are balanced, otherwise differences in
pressure are possible between the hygrometers in the system.
• If the flow control valve needs to be installed upstream of the
sensor, a bellows-type valve should be used.