Van Walt Rain Gauge Operating Instructions Manual page 20

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VAN WALT

Monitoring your needs

• Replace the battery of the datalogger in time with a new battery of the correct type. Chapter

2, "Technical specifications," states the expected life span of the battery. For replacement

of the battery, a battery set is available separately (see Chapter 1.1, "Package contents").

Consult the user manual of the battery set e+ logger (11.41.90.01) to replace the battery

correctly.

If the datalogger does not function correctly after replacing the battery, short circuit the battery for

5 seconds and then end the short circuit in one direct movement.

The rain gauge is factory-calibrated and is supplied with a calibration specification, elucidated

with examples. The instrument is specified with a nominal measuring sensitivity of 0.2 mm rain per

contact. The actual value may lie between 0.197 and 0.204 mm per contact. In addition to the

nominal specification, the calibration specification states the actual measuring sensitivity of the

instrument, the so-called calibration factor. The user has the option of calibrating the instrument, to

which a static calibration is performed. Subsequently, the new calibration factor of the instrument

is determined via a dynamic calibration measurement. If so desired, the Range setting of the

datalogger can then be adjusted in accordance with the new calibration factor.

The static calibration is executed as follows:

• Preceding the static calibration, all maintenance requirements as stated above should be

completed.

• Remove the water-collecting basin and check if the rain gauge is mounted horizontally.

• With a pipette or burette, slowly drip 10.13 cm3 water in the tipping bucket. It should tip with

the last drop from the pipette or burette. If this does not occur, adjust the relevant thumbscrew

and repeat the procedure until the tipping bucket tips at the right moment.

• Repeat the above procedure for the other half of the tipping bucket.

Next, the calibration factor is determined according to the method for dynamic calibration:

• Before the calibration factor is determined, the rain gauge should be connected to the

datalogger, the water- collecting basin should be removed from the rain gauge, and a check

should be performed to see if the rain gauge is standing in the horizontal position.

Number of contacts

96.7 - 96.9

97.0 - 97.4

97.5 - 97.9

98.0 - 98.4

98.5 - 98.9

99.0 - 99.4

99.5 - 99.9

100 - 100.4

Operating Instructions

Rain Gauge

calibrationfactor

[mm per contactsluiting]

0.204

0.203

0.202

0.201

0.200

0.199

0.198

0.197

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