DewPro MMY245
Installation and Operation Manual
GE General Eastern
25
Figure 11
Care should be taken to connect the MMY 245 to systems within the rated pressure range of vacuum to 150
psig. If the process pressure is greater than 150 psig, this method of connection cannot be used.
Transmitters in this configuration usually are not fitted with an orifice but the model number should be
checked to make sure the transmitter is a M/N MMY 30 R1D1A. The validation can proceed with the
single point (recommended) or dual point procedures.
4.4 Field Validator Setup
4.4.1 Matrix Orientation
Once the electrical and mechanical connections have been made the MMY 245 must be configured for the
desired type of calibration. A single point calibration will verify the transmitter reading at the sample dew
point. This new value represents a change in the intercept of the calibration curve only.
A two-point calibration is performed in the same manner as in a single point validation with the additional
step of monitoring a second moisture value (generally that of the ambient air). The MMY 245 values are
assumed to be the field standard and are used to reprogram the EEPROM data in the transmitter. These
values represent a change in the intercept and the slope of the calibration curve. This procedure requires
that the transmitter be valved “off line” and opened to the atmosphere. This is accomplished by
disconnecting the sample line to the portable MMY 245 and unscrewing the orifice to allow the sensor to
equilibrate with the dew point of the ambient air.
The single point calibration is selected by moving through the matrix using the “V” and “H” keys on the
portable to the
V8 H2
and setting the value to
1
. The two-point calibration is selected in the same manner
