Author Topic: Rain Gauge Issues with new VP2  (Read 2649 times)

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Offline azchrisf

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Re: Rain Gauge Issues with new VP2
« Reply #25 on: April 12, 2021, 02:32:53 PM »
I don't know, but from past experience it's not unusual for wildly inaccurate rain gauges to come out of Davis new in the box. Keep in mind the bubble level must be level and in the circle.

It is possible the Vue was overreading, that's why we say the only way to tell for sure what is accurate vs. what is not is to use the Calibration kit the CW2274 posted or send it for calibration.
Davis Vantage Pro 2 Plus 6163 w/ 8 Transmitters!
Also doing Soil and Leaf 4x
WU: KAZGLEND106 CWOP: FW1398 (F1398) Purpleair: 98793/LAZGLEND8
My setup:
https://www.wxforum.net/index.php?topic=41867.0

Offline CW2274

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Re: Rain Gauge Issues with new VP2
« Reply #26 on: April 12, 2021, 04:32:03 PM »
use the Calibration kit the CW2274 posted or send it for calibration.
I didn't mention a kit, but that said, all I used to calibrate my Rainwise bucket is a gallon milk jug and various simple tools. Does the job very nicely too if I may say so myself.
« Last Edit: April 12, 2021, 04:35:24 PM by CW2274 »

Offline azchrisf

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Re: Rain Gauge Issues with new VP2
« Reply #27 on: April 12, 2021, 04:54:38 PM »
use the Calibration kit the CW2274 posted or send it for calibration.
I didn't mention a kit, but that said, all I used to calibrate my Rainwise bucket is a gallon milk jug and various simple tools. Does the job very nicely too if I may say so myself.

My mistake, the Cocorahs gauge I though was a calibration kit just looking at the URL. Sorry LOL

Anyways, something like this then:
https://novalynx.com/store/pc/260-2595-Tipping-Bucket-Rain-Gauge-Calibrator-p1030.htm

I know someone posted the formula for Davis gauges around here somewhere...
Davis Vantage Pro 2 Plus 6163 w/ 8 Transmitters!
Also doing Soil and Leaf 4x
WU: KAZGLEND106 CWOP: FW1398 (F1398) Purpleair: 98793/LAZGLEND8
My setup:
https://www.wxforum.net/index.php?topic=41867.0

Offline Padnandos

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Re: Rain Gauge Issues with new VP2
« Reply #28 on: April 12, 2021, 04:57:53 PM »
I’ve noticed today now especially that both the New VP2 and the Old Vue pick up the same rainfall rates but come out with different rain totals. Difference today between the two was roughly 1mm

Offline CW2274

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Re: Rain Gauge Issues with new VP2
« Reply #29 on: April 12, 2021, 05:04:40 PM »
use the Calibration kit the CW2274 posted or send it for calibration.
I didn't mention a kit, but that said, all I used to calibrate my Rainwise bucket is a gallon milk jug and various simple tools. Does the job very nicely too if I may say so myself.
Anyways, something like this then:
https://novalynx.com/store/pc/260-2595-Tipping-Bucket-Rain-Gauge-Calibrator-p1030.htm

I know someone posted the formula for Davis gauges around here somewhere...
See, I wasn't willing to choke up the ~$140 for the Novalynx, so I made my own for next to nothing.

As far as the Davis "formula", if you referring to the amount required, like I said earlier (I think this thread) the old spoon tipper takes 544ml for an inch of rain. No idea if the new design is the same.

Offline Dj1225

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Re: Rain Gauge Issues with new VP2
« Reply #30 on: April 12, 2021, 06:31:18 PM »
I don't know, but from past experience it's not unusual for wildly inaccurate rain gauges to come out of Davis new in the box. Keep in mind the bubble level must be level and in the circle.

It is possible the Vue was overreading, that's why we say the only way to tell for sure what is accurate vs. what is not is to use the Calibration kit the CW2274 posted or send it for calibration.

Speaking of rain gauge I sent you a message about the Rainwise rain gauge

Offline Padnandos

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Re: Rain Gauge Issues with new VP2
« Reply #31 on: April 13, 2021, 03:43:33 PM »
A snapshot of my setup. The new VP2 on the left and the old Vue on the right


Offline Padnandos

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Re: Rain Gauge Issues with new VP2
« Reply #32 on: April 14, 2021, 03:17:34 PM »
Does having the debris screen removed from the Vue have any effect on the rate of the rain going into the spoon?

Offline azchrisf

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Re: Rain Gauge Issues with new VP2
« Reply #33 on: April 14, 2021, 03:22:38 PM »
The rain rate is only a calculated number - it is based on number of tips in an hour and the bucket weight type, or something like that.
The debris collector, see next response. But It will not affect nor solve the problem you are chasing.
« Last Edit: April 14, 2021, 04:48:46 PM by azchrisf »
Davis Vantage Pro 2 Plus 6163 w/ 8 Transmitters!
Also doing Soil and Leaf 4x
WU: KAZGLEND106 CWOP: FW1398 (F1398) Purpleair: 98793/LAZGLEND8
My setup:
https://www.wxforum.net/index.php?topic=41867.0

Offline Mattk

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Re: Rain Gauge Issues with new VP2
« Reply #34 on: April 14, 2021, 04:41:41 PM »
Does having the debris screen removed from the Vue have any effect on the rate of the rain going into the spoon?

With no Vue debris screen it has been observed in specific types of rain events an overly increase in rain which may be due to the rather large hole in the Vue cone allowing heavy and/or large droplets to directly bounce the spoon

Offline Padnandos

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Re: Rain Gauge Issues with new VP2
« Reply #35 on: April 14, 2021, 05:14:16 PM »
I’m coming to the conclusion that I have my new VP2 too high up off the ground.  If this is the case well then Vantage Vues do better at catching rainfall at height than Vantage Pro2’s.

Offline CW2274

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Re: Rain Gauge Issues with new VP2
« Reply #36 on: April 14, 2021, 05:21:17 PM »
And I'm coming to the conclusion you enjoy doing this... ](*,). Until you have something you KNOW that is accurate, you'll will continue  ](*,).

Offline Padnandos

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Re: Rain Gauge Issues with new VP2
« Reply #37 on: April 14, 2021, 05:27:01 PM »
Lol I’ll just end up driving myself crazy

Offline CW2274

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Re: Rain Gauge Issues with new VP2
« Reply #38 on: April 14, 2021, 05:28:21 PM »
 [tup]

Offline Smithee

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Re: Rain Gauge Issues with new VP2
« Reply #39 on: May 24, 2021, 05:25:35 AM »
Morning - just wondering if you sorted your issues with your VP2? I have just got a new VP2 and it also seems to under record compared to my side by side Vue and CoCoRaHS rain gauge...

Andy

Offline johnd

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Re: Rain Gauge Issues with new VP2
« Reply #40 on: May 24, 2021, 05:41:10 AM »
Morning - just wondering if you sorted your issues with your VP2? I have just got a new VP2 and it also seems to under record compared to my side by side Vue and CoCoRaHS rain gauge...

It really does help if you can (1) confirm that the CoCoRaHS is at the same height and very close by to the VP2; (2) actually quote some numbers; (3) also check & confirm that the numbers relate to the same daily period, ie Vue/VP2 will typically be midnight to midnight for daily totals, whereas CoCoRaHS will be something different. I'd always use CoCoRaHS as the reference rather than Vue.
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Offline Mattk

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Re: Rain Gauge Issues with new VP2
« Reply #41 on: May 24, 2021, 05:55:09 PM »
Having recently checked the calibration of five (5) VP2 (0.2mm) tipping spoon modules (3 from one order and 2 from another) I would have to say these 5 units are very consistent and actually within stated specification of +/-4% with most reading a tad under, average of the 5 (each was checked twice) was 100.5% Standard Dev 3.2%. One would not be expecting any better than that and even thinking of trying to calibrate these any further would not even be a consideration let alone be able to be done properly.

The original VP2 tipping buckets were typically not even close, out of the box could be up to 20+% in error and generally always under reading.

However the VP2 tipping buckets could be easily adjusted, these tipping spoons have no real practical calibration means what so ever and yes I know how the calibration works but there is absolutely nothing practical in calibration terms with these tipping spoons. The non linear nature and having to remove and dissemble/reassemble really makes any form of field in-situ calibration not an option.           

Offline Smithee

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Re: Rain Gauge Issues with new VP2
« Reply #42 on: May 25, 2021, 04:42:18 AM »
Good points (of course) on providing numbers/heights. I have just reset the units and will monitor for the next few weeks, the manual gauge is at the same height and from first impressions, the VP2 is approx 10% too low. However, i will leave them for a while and average them out.

Andy

Offline MuntyWeather

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Re: Rain Gauge Issues with new VP2
« Reply #43 on: June 09, 2021, 06:10:58 AM »
I've been running some comparative measurements of the new tipping spoon and the tipping bucket, both against the CoCoRaHS manual gauge and both 0900-0900 UT.  I thought you might like to see the results.
The bottom line seems to be that the tipping spoon (TS) gives rather tighter agreement than the tipping bucket.   Interestingly, the least squares line (constrained to go through the origin) is not far from 1:1 for both of them.  The tipping bucket calibration was adjusted with a direct calibration (pouring 100ml of water in and counting the tips).  The tipping spoon calibration was 'out of the box'.
« Last Edit: June 24, 2021, 05:51:16 AM by MuntyWeather »

 

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