Vaisala MAWS201 User's Guide download pdf (Page 143)

Chapter 5 _______________________________________________________________Maintenance

VAISALA _______________________________________________________________________ 141

2. Check that the gauge is still level. It is surprisingly easy for an

apparently immovable gauge to become tilted as a result of

small ground movements, vandalism, or just an inquisitive

finger.

3. Clean the spoon from dust and dirt once or twice a year to

ensure a precise measuring.

QMR102

To ensure reliable and accurate measurements, Vaisala recommends

that the following checks be carried out at each visit to the rain gauge.

NOTE

If the gauge is connected to the data logger and the logger is

operating, avoid tipping the cup assembly.

1. Inspect the funnel and filter for any damage or blockage. At

certain times of the year leaves may have accumulated in the

funnel, dirt and dust can also block the filter preventing or

reducing the flow rate to a slow drip into the buckets beneath.

The leaves can easily be removed from the funnel and the filter

can be cleaned by removing the end cap from the filter tube.

Remove the filter material carefully, clean and replace the filter

and cap.

2. Check that the gauge is still level. It is surprisingly easy for an

apparently immovable gauge to become tilted as a result of

small ground movements, vandalism or just an inquisitive

finger.

3. Remove and clean any dirt from the bucket.

4. There will be times when the rain gauge will not log or will be

disconnected from the logger. In such cases, it is a good idea to

check the balance arm of the bucket for stiffness. The easiest

way to do this in the field is to try to balance the bucket in its

center position. It should be very difficult, if not impossible, to

achieve this. If the bucket balances easily then examine the

bucket closely for any dirt or wear on the pivot pin and bucket

tubes.

Calibration

The sensitivity of the rain gauge is accurately calibrated by the

manufacturer to a nominal 0.2 mm/tip. Each rain gauge is supplied

with its own calibration figure. A purpose built calibration rig that

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Vaisala MAWS201 User's Guide Page 143