DewPro MMY245
Installation and Operation Manual
GE General Eastern
10
2.4.1 Mapping spot check route
If more than one sample point is to be checked on a regular basis, it is best to map out the route the
operator should follow. If time permits, the route should be chosen for the best measurements instead of
the shortest distance traveled. Simply stated, this method measures the driest sample first and moves
through the route from the measurements that have proven to be the driest to the wettest in sequence.
This allows the sensor to respond faster since getting wet is naturally faster than getting dry. This
routing can only be determined by trial and keeping good records.
2.4.2 Temporary Monitoring
The MMY 245 is to be used in either a spot check mode or a temporary measurement mode. A spot
check mode is when an operator takes the unit to a sample tap and measures the moisture in the sample
and disconnects the unit and moves on to perhaps the next sample tap. Temporary moisture monitoring
is where the instrument is to be left connected to a sample unattended and the moisture values recorded
electronically or by periodic observation.
The MMY 245 is supplied with two analog outputs for conveniently connecting to an external
recording or logging device. The battery life can support this mode of operation for a few weeks but the
unit also provides for an external DC power source to power the unit. These connections are made
using the cable connection on the front of the unit. The cable can be ordered as an accessory.
Warning: Neither of these connections should be used in hazardous or electrically classified
areas.
2.4.3 Moisture Measurement Practice
Every process and application is different and these differences must be considered; but using good
general practices will result in better and more accurate measurements.
1. Do not introduce samples at greater than the rated pressure of 150 psig (10 barg).
2. Do not introduce samples of gases corrosive to aluminum or gold into the unit. This will damage
the sensor and will void the warranty.
3. Do not introduce samples of known high moisture or samples saturated with water into the unit.
The sensor can be damaged and will not be covered under warranty. Observe the outlet port to see
if the escaping sample shows evidence of aerosols. If so, do not attempt the measurement. If an
attempt is made to measure a sample that drives the reading off scale high, move the black handle
into the bypass position immediately to dry the sensor.
4. Do not introduce dirty samples into the instrument. Filter contaminated or oily streams to prevent
contamination of the sensor and internal piping.
5. Insure plumbing connections are tight. A leak will introduce errors in the measurement,
6. Keep sample lines to measurement taps as short as possible using small diameter (¼”) tubing to
achieve the best response speed.
7. Use stainless steel, copper or PFA Teflon tubing for sample connections for best results.
8. Allow sufficient time to purge the new sample through the sample lines to insure a fresh sample is
provided to the analyzer. This may take a minute or two if the sample tap connection is mounted
directly to the pipe or several minutes if the sample line is necessarily longer to reach the source.
9. Keep good records of periodic measurements. This will allow better planning for maintenance of
process equipment and measurement practices.
2.4.3.1 Checking Dryer Performance
Gas dryers often vary in their ability to dry the gas at any given point in time. Spot checking a dryer can
often produce readings that vary depending on the load of gas flowing through it, the cycle or stage of
operation for the dryer and the condition of the dryer internal mechanical and or chemical elements.
Good record keeping and tracking the initial measurements for longer periods can be helpful in
determining the typical dryer performance in a specific system.
