Topic: VP2 tipping spoon raingauge?

[mauro63]

official davis communication on the new rain gauge 

Hello Mauro,

 Yes, we did recently change out the tipping bucket mechanism on all new VP2 stations.  We will be offering a retrofit kit to update older stations.  Though, it would most likely not be available until January as we are currently using all new mechanisms on new stations builds only.

 

[miraculon]

Are there any data available on the tipping spoon vs. tipping buckets at high rain rates?

Is the emptying rate for the spoon vs. bucket faster? We had heavy rain yesterday and the VP2 was significantly less than either my CoCoRaHS or Novalynx 8" TBR.

During "normal" gentle rainfall with no wind the three gauges agree within 0.01" which it the best you can expect with TBR.

NovaLynx publishes a correction factor chart for in/hr rain rate.

I don't see this under the current VP2 ISS manual, but in the manual for the "Rain Collector II" there is this:

VP2 Rain Collector II
Accuracy  . . . . . . . . . . . . . . . . . . . . . . . .
For rain rates up to 2"/hr (50 mm/hr): ±4% of total or +0.01” (0.2mm) (0.01" = one tip of the bucket), whichever is greater.
For rain rates from 2"/hr (50 mm/hr) to 4"/hr (100 mm/hr): ±5% of total or +0.01” (0.2mm) (0.01" = one tip of the bucket), whichever is greater.

My measurements from yesterday were:
CoCoRaHS:   3.18"
VP2:            2.74"
Novalynx:     3.39"

VP2 was 13.5% lower than the CoCoRaHS. The Novalynx was 6.6% higher. There was a lot of wind, so some variation is due to location and wind currents. My back yard is small and the gauge locations do not comply with established siting guidelines.

For what it's worth, the standard VP2 cone was placed so I did not have the "Aerocone" in place. (getting ready for winter and testing the heater)


Greg H.

[havtrail]

It would be interesting to see the relative accuracy data. Intuitively, the tipping spoon has to tip and then return to position, whereas the paired buckets only need to tip and the other bucket is then already in position. Seems like the paired buckets should be more accurate.

Rich K.

[ocala]

It would be interesting to see the relative accuracy data. Intuitively, the tipping spoon has to tip and then return to position, whereas the paired buckets only need to tip and the other bucket is then already in position. Seems like the paired buckets should be more accurate.

Rich K.

While there is no neutral position for the spoon like the tipping buckets  I just wonder while it's in the process of dumping the load the water   is still pouring in from above. How is that going to be accounted for. Unless it's somehow collected during the dumping process.

[johnd]

I guess it depends whether you're in a monsoon region or not. A rainfall rate of 0.6"/hr, which is pretty steady heavy rain is only one tip of a 0.01" gauge per minute. 5 times that rate (ie 3"/hr) which is more in thunderstorm territory is still only one tip every 12 secs. Higher rates still could give some potential losses I agree, but these could be compensated for in firmware (I don't believe the VP2 does that, though a putative VP3 with a more powerful processor maybe could).

So I'm not sure how much of an issue it is in practice and probably not very different from a TBR where rainfall is missed as the buckets tip.

[miraculon]

The rain rate from this rain event hit 8.11 inch/hr. 

It was really coming down, the visibility was poor. (I also discovered a roof leak that I thought was previously fixed. )

I'll attach the Weatherlink 2 plot from that time period. It was an "off the charts" rain event.

I also added the "rain rate max" from the Novalynx 8" gauge. (from meteohub plots) It also peaked out at about 8"/hr.

Greg H.

[BCJKiwi]

It would be interesting to see the relative accuracy data. Intuitively, the tipping spoon has to tip and then return to position, whereas the paired buckets only need to tip and the other bucket is then already in position. Seems like the paired buckets should be more accurate.

Rich K.

While there is no neutral position for the spoon like the tipping buckets  I just wonder while it's in the process of dumping the load the water   is still pouring in from above. How is that going to be accounted for. Unless it's somehow collected during the dumping process.

From the photos,  back of the spoon is very close to the the pivot, and, also appears to be offset from the center of the rain bucket so the drips would always land in the spoon even when it is tipping - so should be better than the tipping buckets.

[mauro63]

I believe that the single spoon system can be more precise, I will try to explain the reasons but I apologize in advance for the bad English 
in double spoon systems, most of the errors are due to the amount of water lost during the tipping phase, when the amount of water is enough for tipping, during the necessary time, water continues to fall on the same spoon without be measured, this until the tipping is complete allowing the opposite spoon to start collecting water

in a single spoon system the problem remains, but lesser than in a tipping bucket system,  the water collection start time after the tipping will be smaller, that is until the spoon has been lifted enough to make sure that the water does not come out of the spoon

Another aspect is the tipping speed, we don't know if a tipping spoon is more or less fast than a tipping bucket system, today I asked this information to Davis

Another primary aspect is due to the constructive semplicity, a single spoon it's more easy to calibrate, there's no balance problem as it often happens in a tipping bucket system.

A secondary problem regarding the accuracy is the lost of tipping count, if the water on one of the spoon isn't enough for tipping, this water will be not counted and will lost for evaporation, but this problem is the same in a single spoon system

I do not know if I was clear enough, in Italian I would have a lot less problems, please forgeve me 

[mauro63]

FOUND IT!

This is the 2015 International Patent that DAVIS was granted on a "Weighing Precipitation Gauge" (not called 'tipping spoon'):

https://patentimages.storage.googleapis.com/57/44/5c/6d00e340b2670a/WO2015148320A1.pdf

See paragraph [0051].

Quoted from paragraph [0060]: "Unlike "tipping bucket' rainfall gauges known in the art, because the collected fluid F has been measured during its accumulation, the volume at the time of tipping is not significant to record or to base a calculation on for calculating or otherwise determining rainfall or precipitation. Accordingly, any error associated with variation in the volume of fluid F at the tipping point of the bucket, as seen in rain gauges known in the art, does not occur.

wow!!!
therefore the idea of improving the vp2 rain gauge dates back to 2015 ?? three years to process and apply?

[Mattk]

FOUND IT!

This is the 2015 International Patent that DAVIS was granted on a "Weighing Precipitation Gauge" (not called 'tipping spoon'):

https://patentimages.storage.googleapis.com/57/44/5c/6d00e340b2670a/WO2015148320A1.pdf

See paragraph [0051].

Quoted from paragraph [0060]: "Unlike "tipping bucket' rainfall gauges known in the art, because the collected fluid F has been measured during its accumulation, the volume at the time of tipping is not significant to record or to base a calculation on for calculating or otherwise determining rainfall or precipitation. Accordingly, any error associated with variation in the volume of fluid F at the tipping point of the bucket, as seen in rain gauges known in the art, does not occur.

wow!!!
therefore the idea of improving the vp2 rain gauge dates back to 2015 ?? three years to process and apply?

The principle is no different to the Vue. However a clogged tipper is no different to a clogged spoon and that's something that has not been addressed for the past 20+ years.

[mauro63]

FOUND IT!

This is the 2015 International Patent that DAVIS was granted on a "Weighing Precipitation Gauge" (not called 'tipping spoon'):

https://patentimages.storage.googleapis.com/57/44/5c/6d00e340b2670a/WO2015148320A1.pdf

See paragraph [0051].

Quoted from paragraph [0060]: "Unlike "tipping bucket' rainfall gauges known in the art, because the collected fluid F has been measured during its accumulation, the volume at the time of tipping is not significant to record or to base a calculation on for calculating or otherwise determining rainfall or precipitation. Accordingly, any error associated with variation in the volume of fluid F at the tipping point of the bucket, as seen in rain gauges known in the art, does not occur.

wow!!!
therefore the idea of improving the vp2 rain gauge dates back to 2015 ?? three years to process and apply?

The principle is no different to the Vue. However a clogged tipper is no different to a clogged spoon and that's something that has not been addressed for the past 20+ years.

I'm not sure this is the same of davis vue, the document is dated 2015, the vue, if I'm not wrong, is on the market from 2010?

[johnd]

I'm not sure this is the same of davis vue, the document is dated 2015, the vue, if I'm not wrong, is on the market from 2010?

Mattk is talking about clogging in the funnel, not whether it's a spoon or TBR. And yes the tipping spoon in the Vue has been around since 2010. But presumably Davis have tweaked the design of the Vue spoon principle sufficiently that they feel it's worthy of a new patent application.

[mauro63]

I'm not sure this is the same of davis vue, the document is dated 2015, the vue, if I'm not wrong, is on the market from 2010?

Mattk is talking about clogging in the funnel, not whether it's a spoon or TBR. And yes the tipping spoon in the Vue has been around since 2010. But presumably Davis have tweaked the design of the Vue spoon principle sufficiently that they feel it's worthy of a new patent application.

I understood, sorry, you know my english is disgraceful 
about the clogging in the funnel I cannot see the problem, every rain collector has the same problem, the filter has the ability to prevent leaves, insects or anything from falling inside the measurement system, but it can not prevent the cone from closing the passage of water in excess of debris, but this is a problem for all rain gauges, even professional ones , even my deltaohm, which costs as a complete vp2, has a decidedly refined filter but if it clogs it can not do anything, it only counts the good maintenance

I'm wrong?

[johnd]

I think that Mattk believes that Davis could substantially improve the clogging resistance of eg the VP2 gauge. But agreed, this is nothing directly to do with the spoon vs TBR discussion.

[Mattk]

I'm not sure this is the same of davis vue, the document is dated 2015, the vue, if I'm not wrong, is on the market from 2010?

Mattk is talking about clogging in the funnel, not whether it's a spoon or TBR. And yes the tipping spoon in the Vue has been around since 2010. But presumably Davis have tweaked the design of the Vue spoon principle sufficiently that they feel it's worthy of a new patent application.

about the clogging in the funnel I cannot see the problem, every rain collector has the same problem, the filter has the ability to prevent leaves, insects or anything from falling inside the measurement system, but it can not prevent the cone from closing the passage of water in excess of debris, but this is a problem for all rain gauges, even professional ones , even my deltaohm, which costs as a complete vp2, has a decidedly refined filter but if it clogs it can not do anything, it only counts the good maintenance

I'm wrong?

Maintenance is one thing but design is totally something that can prevent a lot of the Davis rain collector issues and this is certainly not a problem with all rain gauges. A so called debris collector or grate does very little to solve clogging. Has been discussed before

http://www.wxforum.net/index.php?topic=32511.msg343315#msg343315

[miraculon]

FOUND IT!

This is the 2015 International Patent that DAVIS was granted on a "Weighing Precipitation Gauge" (not called 'tipping spoon'):

https://patentimages.storage.googleapis.com/57/44/5c/6d00e340b2670a/WO2015148320A1.pdf

See paragraph [0051].

Quoted from paragraph [0060]: "Unlike "tipping bucket' rainfall gauges known in the art, because the collected fluid F has been measured during its accumulation, the volume at the time of tipping is not significant to record or to base a calculation on for calculating or otherwise determining rainfall or precipitation. Accordingly, any error associated with variation in the volume of fluid F at the tipping point of the bucket, as seen in rain gauges known in the art, does not occur.

wow!!!
therefore the idea of improving the vp2 rain gauge dates back to 2015 ?? three years to process and apply?

The wheels at the USPTO grind quite slowly. I have been inventor/co-inventor on a number of US Patents, and it does take years for the process to complete. Three years sounds typical. (of course it has now been 5+ years since my last one was issued).

Greg H.

[rwilhour]

Hi Miraculon

Here is a photo of the unboxing of my VP 2 showing the tipping spoon from the other side.

Ryan Wilhour from Scaled Instruments here.   There seems to be a model number on that tipping spoon It looks like it says 7344.456.  Can you provide all the text on the label for me?  I am going to randomly throw this in with my next freight order from Davis and see what happens .

[PaulMy]

I needed to call Davis Support yesterday on an issue with my VP2 rain tipping and they are sending new tipping parts and metric adapter.  I asked support whether the new tipping spoon might be a better solution and he said the tipping spoon is only available for the Vue.  When I mentioned about the tipping spoon for VP2 as discussed here he said he had not been made aware and is just going to send the replacements parts for the original VP2 tipper.  I guess the new VP2 tipping spoon info hasn't gone through the Davis knowledge stream.

Enjoy,
Paul

[johnd]

My understanding is that the spoon variant is not in mainstream production as yet. The small number of 'spoon VP2' stations that have been produced were intended for extended field testing although one or two may have 'escaped' (and might therefore be collectors' items  ). It's rumoured that full production may not start for a few months yet and once the wider test results are in.

[johnd]

"Escaped" or VERY clever creation of "pre-marketing" buzz (like these posts)?

Yes, maybe. But it's a fairly trivial thing to create a sort of viral campaign around. Wouldn't Davis reserve that tactic for prior to a more exciting product launch, not that there's too much obviously on the horizon right now while EM and 2.0 are still being worked through?

[rwilhour]

"Escaped" or VERY clever creation of "pre-marketing" buzz (like these posts)?

Yes, maybe. But it's a fairly trivial thing to create a sort of viral campaign around. Wouldn't Davis reserve that tactic for prior to a more exciting product launch, not that there's too much obviously on the horizon right now?

Like a "Pro3"!

Realistically, just reading the tea leaves, Davis improving yet another aspect of the Pro2 leads me to believe that an anticipated Pro3 is that much further down the road.

[johnd]

Yep, "piecemeal" rather than "wholesale" upgrade/improvement of a sacred cow product?!? 

Well, and at the risk of going OT somewhat, if we were to separate out inside and outside, what changes would you like to see in the outside sensors? I can't personally see too much that I would change. Yes I'd like to see a more consistently accurate rain gauge (but maybe (?) the spoon can deliver that). And personally I wish the rain gauge were more easily ground-mountable. And I dare say that the SHT31 critics will chime in.

But those relatively limited details aside, what else would you change - while sticking to the VP2 budget? (ie I'm sure we'd all like to see an ultrasonic anemometer for instance but I see no evidence that is feasible without increasing the price substantially).

Console features are probably a different matter, but I'm just thinking of the outside sensors here.

[galfert]

Oh neat a single tipping spoon like in my Ambient hardware that I've been criticized for using that does not having double tipping buckets.

In all fairness I'm sure all tipping spoons are not created equal. Like I'm sure this new VP2 design is surely better than the Vue design. But still...what goes around comes around.

Look, please don't misread what I'm saying. I'm not evangelizing Ambient. I'm a big Davis fan and I'm anxiously waiting for a VP3. Glad to see Davis making improvements. Next focus should be that awfully dated looking console. For me Davis only needs to do two improvements and it is as good as a VP3. Change the console to nice color touch display, add built in WiFi logger with direct data access via network, and secondly change from LSS protocol to I2C protocol Sensirion sensors (make it a SHT85).

[nincehelser]

Oh neat a single tipping spoon like in my Ambient hardware that I've been criticized for using that does not having double tipping buckets.

In all fairness I'm sure all tipping spoons are not created equal. Like I'm sure this new VP2 design is surely better than the Vue design. But still...what goes around comes around.

(*sigh*)  The Ambient is much like a La Crosse single tipper, Galfert.

[galfert]

Oh neat a single tipping spoon like in my Ambient hardware that I've been criticized for using that does not having double tipping buckets.

In all fairness I'm sure all tipping spoons are not created equal. Like I'm sure this new VP2 design is surely better than the Vue design. But still...what goes around comes around.

(*sigh*)  The Ambient is much like a La Crosse single tipper, Galfert.

Hmmm... Are you sure? .Let's make sure we keep the pecking order in line.
(Vaisala + RMY) > Davis > Acurite > Ambient > La Crosse > OS > weather rock on rope.