Xylem DH-21 - Manual (Page 15)

DH-21
Installation 2-3
2.1.3 Environmental Concerns
Through years of experience dealing with measuring in the environment, we have learned that
Mother Nature is very unforgiving to electronic equipment. There are several environmental
concerns with respect to installation and use of the “W
ATER LOG”.
1. Although the “W ATER LOG” is submersible, it cannot be frozen. Damage will occur to the
sensor if it is frozen. Transducers which are installed in geographical areas with harsh
winters should be removed for the winter unless they are deep enough in the water that there
is no danger of freezing. Ice may form around the vent tube without causing damage or
performance degradation. However, the vent tube should be placed so as to minimize the
possibility of it being ripped as the ice shifts or breaks up during times of thawing.
2. As with all plastics, the polyethylene vent tube is sensitive to ultraviolet (UV) light. If
subjected to intense UV light for extended periods of time, rotting of the tube will occur.
Whenever possible, precautions should be taken to protect the above-water portion of the
vent tube from sunlight.
3. Experience has shown that if part of the sensor enclosure of the “W ATER LOG” is above the
water and exposed to sunlight (e.g. installed in shallow water), a temperature gradient can
occur inside of the enclosure which will cause a partial pressure on the reference side of the
sensor. This pressure will raise or lower the “W
ATER LOG” pressure reading depending on
the polarity of the partial pressure. This is a “Laws of Physics” problem not unique to
W
ATER LOG ® Series transducers. It can easily be overcome by installing the transducer
horizontally so that the entire enclosure is covered by water.
2.2 Connecting the “W ATER LOG” to a Computer
To connect the “ W
ATER LOG” to your computer, remove the cap on the RS-232 connector and
plug the mating end of your RS-232 cable into it. Connect the other end of the RS-232 cable to a
serial port on your computer (COM 1 or COM 2) and run the WATERLOG.EXE software.
Note: Do not leave the “ W
ATER LOG” connected to a computer for long periods of time. By
doing so, the “ W ATER LOG” stays in an active state drawing its maximum current
continuously. This will greatly shorten battery life.
Figure 2-2 shows the pin configuration for both ends of the RS-232 cable.