This topic is here simply to list and describe the different types of rain gauge used in Davis stations to allow users to understand which type is fitted to their station. Troubleshooting advice for rain gauge issues will be found in the introductory Rain gauge faults topic.
There are three aspects to understanding which type of rain gauge you nay be using: The tipper mechanism; the gauge increment; and, for VP2 stations, the type of gauge base, as explained below.
Tipper mechanisms
Davis rain gauges have used two distinct measurement mechanisms, depending on model. The Vantage Pro 2 stations (and forerunners) manufactured until late 2019 use what’s often referred to as a tipping bucket raingauge (TBR) that employs a two-sided seesaw mechanism, while all Vantage Vue stations plus VP2 models from 2020 on use a single bucket, referred to as a tipping spoon type. These two alternatives are described further below.
Whatever the tipper type, rainfall is measured in exactly the same way – the transmitter SIM board and console simply count the number of tips and convert this to a rainfall amount. It’s always worth remember that the only piece of information passed on to console and also, independently, to any software, is the number of tips. This is why it is essential that console and software settings both specify accurately the rain gauge increment, otherwise the conversion from number of tips to rainfall amount cannot be made correctly.
Rain gauge increments
Both Vue and VP2 types come in two different rainfall increments – US units (0.01”) and metric units (0.2mm). Note that the measurement unit is distinct from the display unit – it is entirely possible to measure rainfall with a 0.01” gauge but to display the results to full accuracy in metric units (and vice versa).
Originally, Davis only manufactured gauges with the 0.01” increment. But since about 2010 (roughly) the 0.2mm option has been added to satisfy those users who preferred their measurement increment unit to be metric as well. The 0.2mm increment tipper is widely sold around the world and is usually the default increment outside of the US. The 0.2mm gauge is also available in the US in stations and gauges sold as the ‘M’ variants (M for metric of course).
Vue rain gauge
The description below focuses mostly on rain gauges compatible with the Vantage Pro 2 stations. There has only ever been one design of tipping spoon mechanism for Vue stations, which is an integral part of the Vue all-in-one ISS design. Replacement spoon mechanisms for the Vue are available as a spare part and VP2 rain gauges cannot be used with a Vue station.
VP2 Rain gauge tipper and base types, organised by date of introduction and part number:
7852: The original Weather Monitor II rain gauge which was a separate gauge with a 12m cable and flat base for ground mounting and introducing the tipping bucket mechanism used in all VP2 gauges until about 2019. Anyone originally wishing to use a separate rain gauge with a VP1 or::VP2 station could buy one of these units and plug it in to the SIM board of a VP1 or VP2 ISS with which it was fully compatible.
615x and 616x VP1 and VP2 stations: These stations of course use a rain gauge that is integrated into the design of the ISS and the base of the gauge instead of being flat incorporates a pole-mounting bracket and support for the white radiation shield below. But, in practice, the tipper mechanism and the rain gauge funnel were identical to the 7852 gauge and these parts could be used interchangeably between ISS and 7852.
7852 and 7852M (2014 version) A redesigned version of the rain gauge funnel was introduced with spikes around the top as an anti bird-perch measure. The same improved funnel was also used in the 615x and 616x VP2 stations. The straight 7852 version was supplied with tipper calibrated to 0.01” and the 7852M (metric) calibrated to 0.2mm.
7857 and 7857M (2015) This is a version of the separate 7852 rain gauge that use the base from the ISS rather than the flat base of the 7852 model. It is therefore suitable for pole-mounting rather than ground-mounting. Straight 7857 and 7857 designations as per 7852.
2017 Aerocone revisions: In 2017 a completely redesigned funnel/cover for the gauge was released with a pronounced slim waist and intended to reduce the effects of wind on rain catch and thereby to improve gauge accuracy. This was introduced into all new VP2 stations and was also available as a separate 6462 Aercone upgrade kit for existing users. In addition, the 7852 and 7857 parts were replaced by two new part numbers:
6463 and 6463M flat-base Aerocone gauge:Replaces 7852 with flat base and fitted with the new Aercone funnel. Available in both plain 6463 (0.01”) and 6463M (0.2mm) increment versions.
6465 and 6465M pole-mounting Aerocone gauge:Replaces 7857 with pole-mounting base and fitted with the new Aercone funnel.. Available in both plain 6465 (0.01”) and 6465M (0.2mm) increment versions.
2020 New tipping spoon versions The previous tipping bucket seesaw mechanism was replaced with the new tipping single spoon mechanism. This redesign was introduced into all VP2 ISS units during 2020 without any change of station designation. But the 6463 and 6465 parts were renumbered as below:
6464 and 6464M flat-base rain gauge with tipping spoon:Exactly as previous 6463 with Aerocone but with tipping spoon mechanism.
6466 and 6466M pole-mounting rain gauge with tipping spoon:Exactly as previous 6465 with Aerocone but with tipping spoon mechanism.
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