Hobo MX Series Manual page 6

Update the firmware on the logger. A logger
>
readout will be completed automatically at the
beginning of the firmware update process
Important: Before updating the firmware on
the logger, check the remaining battery level
and make sure it is no less than 30%. Make
sure you have the time to complete the
entire update process, which requires that
the logger remains connected to the device
during the upgrade.
Deploying the Logger
The logger is designed to be easy to deploy in many
environments. The logger includes an absolute pressure sensor
and a barometric pressure sensor so no vent tube is required.
Follow these guidelines when deploying the logger:
• The absolute pressure sensor is temperature
compensated over the range of 0° to 40°C (32° to 104°F).
The barometric pressure sensor is temperature
compensated over the range of -20° to 50°C (-4° to
122°F). To obtain the highest level of accuracy, both the
sensor end and top end units of the logger should be
allowed to come to full temperature equilibrium
(approximately 20 minutes) before the reference level is
entered.
• Sudden temperature changes should be avoided.
• When deploying the logger in a well, make sure the well
is vented to the atmosphere. Typically, a small hole can
be drilled 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).
• The sensor face located in the nose cone of the sensor
end needs to be in the water to measure water level.
Make sure the
sensor face
(represented by
dashed lines in
this diagram) is in
the water to
measure water
level
10.0 mm (0.39 in.)
1-508-759-9500 (U.S. and International)
1-800-LOGGERS (U.S. only)
HOBO MX Water Level Logger (MX2001-0x) Manual
• There is a vent for the barometric sensor at the top of
the logger (in the top end). This vent must not collect
water or it will block proper barometric pressure
readings. To avoid collecting water, the logger should be
hung vertically and the vent hole in the well cap should
not be 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.
• Consider using slots for a mounting bolt 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.
• Any change in length of the logger cable will result in a 1-
to-1 corresponding error in the depth measurement.
Always pull-test a cable prior to deploying a logger in a
well to make sure it does not stretch.
• The top of the logger must be close to the surface and
not shielded in metal so that your phone or tablet 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
• To prevent the sensor from moving in currents and to
ensure the support cable is kept straight during
deployment, you may need to add a weight to the
suspension cable just above the sensor or hang a weight
below the sensor. In some cases, you may need to both
add a weight and use a stilling well.
• Be very careful not to exceed the burst pressure for the
sensor. The pressure sensor will burst if the maximum
depth is exceeded (see Specifications). The sensor should
be positioned at a depth where it will remain in the water
for the duration of the deployment, but not exceed the
rated bursting depth.
• Avoid deploying the top-end unit in direct sun as that can
lead to more rapid temperature swings, which can lead
to more measurement error and possibly hurt logger
reliability.
To deploy the logger:
1. Make sure the top end is connected to the sensor end with
the water level logger cable as described in Getting Started
with the Logger.
2. Attach any small parts, such as bolts with nuts, before you
go into the field so you don't risk losing them in the field.
3. Lower the logger into the well or stilling well.
6 www.onsetcomp.com