Comparing the rainfall measured by your Davis® Rain Gauge against the local BOM rain measurement, or the local weather report, or even your neighbours rain gauge, is not an accurate comparison. Rainfall can be very localised and rainfall volumes can vary greatly, even over small distances.
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The small, tube style rain gauges that are available from hardware stores, are not an accurate way to measure rainfall. If a manual rain gauge is to be used as a reference, it should be at least 4 inches wide, and sited adjacent to the Davis Rain Gauge, to provide a reasonable level of accuracy. A gauge with an 8 inch aperture will be even more accurate.

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When determining whether your Davis® Rain Gauge is measuring rainfall accurately, please ensure you are comparing the most current measurements with a known, accurate, local source, such as described above.

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Most inaccuracies in rainfall measurement with the connected rain gauge are caused by debris in the rain bucket and/or tipping spoons or damage to the post/bucket, causing the bucket to be unbalanced. These causes can be avoided or quickly rectified through regular inspection and maintenance.

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After completing the maintenance procedure, observe the next rainfall event and determine if the gauge is now reading accurately by comparing it to an accurate local source. Preferably this comparison source is a 4 inch or 8 inch aperture rain gauge, correctly installed adjacent to your Davis® Rain Gauge.

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If you believe your Davis® Rain Gauge is still reading inaccurately after these checks, please get in touch with LX INCYT Support contact@incyt.io so that we can provide assistance.

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Maintenance

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To maintain accuracy of your rainfall measurements and reporting, your Davis® Rain Gauge should be inspected and cleaned on a regular basis.

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The maintenance interval will vary depending on numerous factors such as weather conditions and seasonality, and users will need to decide how often their specific rain gauges require inspection and maintenance. Some of the things to consider might be:

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Recent farm operations that may have introduced debris into the bucket i.e. from using machinery or ploughing in the area,
Seasonal issues with insect intrusion,
Periods of high bird activity,
Chewing activity or damage from livestock or wild animals in the area
Blowing dust into the tipping bucket,
Inclement weather such as flooding around the base of the pole or high winds may have caused subsidence or tilting of the bucket.

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Any of these issues can affect the accuracy of your rain gauge, so it is important to inspect and maintain your specific gauge as often as necessary. Generally if you have correctly installed the rain gauge and pole with concreting at the base, the level should be correct and simply cleaning the tipping bucket will be sufficient. However it is good practise to check the level periodically and keep the tipping bucket clean and free of debris to allow for the most accurate reporting through the INCYT app.

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Equipment Required

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Soft damp cloth
Tools and concreting equipment where installation maintenance is required

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Procedure

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Make a visual inspection of the rain gauge and associated cabling. Ensure there is no obvious physical damage from animals or machinery.
Remove the rain bucket from the base, by twisting it counter clockwise.
Inspect inside the rain bucket for any debris, such as leaves, twigs, spider webs, etc. If necessary, you can remove the debris screen at the bottom of the bucket, by twisting counter clockwise.
With a soft damp cloth, clean any debris from the bucket, screen and tipping spoons. Ensure you clean any accumulated dirt from inside the tipping spoons.
Check the drain holes under the tipping spoons are clear.
Check the levelling bubble, and ensure the base of the rain gauge is still level, with the bubble in the centre of the black circle. A level base is critical to the accurate operation of the rain gauge.
If you need to re-level the base, loosen the U-bolts, and level accordingly.
Reattach the rain bucket and debris screen.

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Test and calibration of a Davis® rain gauge

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If you suspect your rain gauge is reading incorrectly you can perform the following test and calibration procedure.

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The following testing and calibration procedure applies to the Davis® double tipping rain gauge only. You can check which type of gauge you have by removing the rain bucket by twisting anti clockwise and lifting it off. The double tipping rain gauge mechanism can be identified by the 2 silver cups.

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If you suspect your Davis® Rain Gauge (double tipper) is not recording rain accurately, you should first check that your gauge is clean and level, and that you are comparing your readings to an appropriate alternative device.

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To test the accuracy of the Davis® Rain Gauge, you need to pass an exact amount of water (128 ml) slowly through the rain collector, and count the number of “tips” of the mechanism. This 128 ml is the equivalent of 6mm of rainfall, or 30 “tips” of the bucket mechanism.

Note: When testing and calibrating your Weather Station or Rain Gauge, it should be disconnected from the Bluenode to ensure readings are NOT recorded to the Dashboard.

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The most difficult aspect to this calibration procedure is coming up with a way to slowly drip the water into the collector, to ensure the tippers aren’t overwhelmed. There’s several ways you can do this, but this method utilises commonly found household items that can be easily assembled.

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Material Requirements

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Container (Jug) for water

Digital weigh scales

128ml of water

Funnel

Silicone tube nozzle

Adjustable Flow Garden Irrigation dripper

Support for dripper system over rain collector

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Testing Procedure

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Assemble your “dripping” device. To do this, you can use a Funnel, an Adjustable Flow Garden irrigation dripper, and a nozzle for a silicone tube. (All readily available cheaply from a Hardware store). The Adjustable Flow Garden irrigation dripper should be fitted securely into the end of the silicone tube nozzle, and the funnel then placed firmly into the other end as shown. Adjust the dripper to roughly the 1/2 way mark and test to make sure water drips through freely, and there are no leaks from any joins.

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Unplug the cable from the bottom of the Bluenode, to ensure you don’t record the rain on your dashboard.

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Check that the rain collector is free from all debris and the drain hole in the bottom is not blocked.

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The easiest way to accurately measure out 128 ml of water is to weigh it – i.e., 128g = 128ml

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Place your dripping device over the Rain collector as shown.

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Once you have everything set up, pour the 128ml of water into the funnel and allow the water to drip into the collector. You should hear the tipping mechanism activating as the water flows through.

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If you have used the adjustable nozzle, as specified above, you can adjust the rate at which the water drips. You should be aiming to drip the 128ml of water into the bucket over approximately a 10-minute period. You will need to listen closely, to hear the tippers activate. 128ml of water should equate to 30 tips of the mechanism.

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Record the number of tips you hear, and if possible, repeat the procedure 2 or 3 times to ensure you get a consistent result.

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NOTE: At the end of each test, check how much water is sitting in the tipper, to ensure you account for all the water in the system. You might hear 27 tips, and the tipper is half full. You could call that 27.5 tips.

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Calculate the percentage of over reading or under reading, and if required, adjust the calibration of your rain gauge as follows.

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Calibration Procedure

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NOTE : This calibration applies to the “double tipper” mechanism only.

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Once you have worked out the percentage over or under, that your rain gauge is reading, its possible to physically calibrate the tipping mechanism via the adjustment screws.

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A full turn of the screws anti clockwise (both must be adjusted) will increase the rain readings by approximately 6%. Likewise, a full turn clockwise will decrease readings by approximately 6%.

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Prior to adjusting the screws, it’s a good idea to mark the starting point on the screw head and the rain gauge base.

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After adjusting BOTH calibration screws the desired amount, retest the gauge.

If necessary, make minor adjustments and retest, until the rain gauge is reading accurately.