HOBO MX Water Level Logger (MX2001-0x) Manual
U.S. and International Sales: 1-508-759-9500 6
www.onsetcomp.com
Deploying the Logger
The logger is designed to be easy to deploy in many
environments. Follow the guidelines and steps in this section
for deploying the logger.
Guidelines for Deploying the Logger in a Well
The HOBO MX2001 logger top-end unit (MX2001-TOP) is IP67
rated; it is weatherproof, but not waterproof. It is not rated
for continuous, humidity-saturated environments.
This logger includes an internal barometric sensor for
barometric compensation and for calculating water level data.
There is a vent with a hydrophobic membrane that allows the
logger to sense barometric pressure while keeping water out.
The membrane on the vent can withstand splashing but it
should not be submerged
The vent membrane keeps out most moisture, but deploying
these loggers in a continuous, highly saturated well
environment can eventually lead to condensation inside the
logger. This can be further worsened by extreme temperature
cycling, such as wells that are in direct sun and shallow water
tables that are close to the logger.
Adequate air flow is required to ensure condensation is
minimized on and around the MX2001-TOP.
Wells with Normal Humidity Levels
For wells with normal outdoor humidity levels, drill a small vent
hole in the side of the well cap to ensure that the pressure
inside and outside the well is at equilibrium. You can also use
the Onset well cap (WELL-CAP-01).
Wells with Sustained Humidity Levels
For wells with sustained levels of high humidity, the barometer
vent in the top-end unit must be isolated from the high
humidity in the well.
•
If you are deploying the logger in a well larger or smaller
than 5 cm (2 inch), mount the MX2001-TOP outside the
well and make sure it is shaded so that it is never in
direct sun (the temperature extremes caused by being in
the direct sun will reduce the accuracy).
•
If you are deploying the logger in a 5 cm (2 inch)
diameter well, use the Onset well cap (WELL-CAP-01) to
suspend the logger and sensor in the well. Use the
included rubber grommet to isolate the top section of
the MX2001-TOP and add a ventilation area above the
grommet as shown in the following example. Additional
grommets are available at www.onsetcomp.com (part
number GROMMET-5). To install the grommet with the
logger:
1.
Drill two 3 mm or 1/8 inch holes on opposite sides of
the well cap for cross ventilation. The holes should be
just above the top of the grommet when installed as
shown.
2.
Install the grommet with the upper ring sitting on top
of the well as shown.
3.
Install the well cap on top of the well (refer to the
Onset Well Cap Installation Instructions at
www.onsetcomp.com/support/manuals
).
4.
Install the mounting disk for the well cap on the top
end of the logger.
5.
Feed the MX2001 sensor end, cable, and top end
through the grommet until the mounting disk is
seated.
If your well must remain sealed or there is no way to avoid a
continuous saturated environment, use non-vented water level
loggers, such as the HOBO U20 or U20L water level loggers.
Other Well Mounting Considerations
In addition, follow these guidelines when deploying the logger
in a well:
•
To avoid collecting water in the barometric pressure
vent, hang the logger vertically and make sure the vent
hole in the well cap is not oriented directly above the
vent in the top end of the logger. If the logger must be
mounted at an angle, the vent in the top end should
point down so that any water will drain out of it.
•
If you are not using an Onset well cap, consider using
slots for a mounting bolt used to suspend the logger at
the top of the well rather than holes so that the logger
can be pulled up easily for well access without having to
remove nuts in the field. This can reduce the chances for
small parts falling into the water and being lost.
•
The top of the logger must be close to the top of the well
and not shielded in metal so that your mobile device or
computer can connect to it. The maximum range for
communication is 30.5 m (100 ft) with full line-of-sight.
•
If you are deploying the logger in a lake, river, or stream,
you must first build a stilling well to protect the logger,
sensor, and cable. A simple stilling well can be constructed
with PVC or ABS pipe. A properly constructed stilling well
holds the sensor in position and protects the logger
components from currents, wave action, and debris.
Suspend the sensor end in the stilling well so it is always
underwater, but not on the bottom to be buried by silt.
For more information, see the Technical Application Note
for Constructing a Stilling Well at:
http://www.onsetcomp.com/water_level_stilling_well.html
