Cermet II User’s Manual
Michell Instruments
1
INTRODUCTION
1 INTRODUCTION
The Cermet II hygrometer is an instrument designed for the continuous online
measurement of moisture content in non-corrosive gases, over an operational range
of -100 to +20°C (-148 to +68°F) dew point and equivalent units (see Technical
Speci
fi
cations, Appendix A).
The system comprises a programmable monitor con
fi
gured to accept a unique Michell
data string from the Cermet II transmitter. The zero and span of the monitor are set to
cover the dew-point range -100 to +20°Cdp (-148 to +68°Fdp) at operating pressures
up to 45 MPa (450 barg / 6500 psig).
Two alarm outputs are provided for connection to external systems which are user-
con
fi
gurable both in terms of setpoint and operating mode. Current output is standard
and factory set at 4-20 mA (or optionally set at 0-20 mA or 0-10 V).
The monitor has a pressure input channel for any industry standard 2-wire pressure
transmitter. In addition to providing a pressure measurement, the pressure signal can
be used to provide real-time pressure compensation on the primary channel when
displaying ppm values. The customer can also set a
fi
xed pressure compensation value.
The pressure input only affects the ppm
V
(parts per million by volume), lbs/MMSCF
(pounds per million standard cubic feet) and g/m
3
(grams per cubic meter) units. For
dew point, the displayed value is a pressure dew point.
1.1 Features
•
Wide measurement range, calibrated -100 to +20°Cdp
•
±1°Cdp measurement accuracy
•
Pressure sensor input
•
Up to 4 alarm relays
•
User selectable units of measurement
•
Easy to read display
•
Analog and digital outputs
