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Davis Instruments Weather Stations / Re: Tipping spoon (new type) - adjusting
« Last post by GazSlab on Yesterday at 08:40:17 PM »Hi Phil,
I have a Davis VP2 located in Indonesia but purchased in Australia from the Davis Australian agent. I recently fitted the tipping spoon upgrade, the old one was the double tipping bucket. The tipping spoon was also purchased from the Davis Australia agent. I've compared measurements between the VP2 and a 4" opening diam Nylex manual gauge. The Nylex gauge is identical in design to the American CocoRAHS gauge, but it does not come with any calibration certification.
I compared readings from 29th Jan to 9th Feb; Davis 195.8mm, Nylex manual 186.7mm.
So in aggregate the Davis gauge reads 4.9% over.
The manual gauge is about 15 meters away from the Davis gauge and also the manual gauge is 4ft off the ground whereas the Davis is on the shed roof about 12ft off the ground.
With the new tipping spoon I've found the Davis reads over during heavy showers and reads slightly under during lighter rain. During the trial period we had one day of heavy rain and the Davis recorded 98.8mm whereas the manual gauge recorded 90.6mm. My aero cone inner surface is quite rough so water is likely getting caught up in the cone then flashing off during the light events. I think this has no effect during heavy events. I need to purchase a new cone (expensive in Indonesia due to import duties, will buy in Aust. another time). If the majority of the rain is light in your location then this may contribute to your under reading?
My next move is to mount the manual gauge next to the Davis gauge on top of the shed to do a better comparison. However in summary I feel the Davis gauge with the tipping spoon reads slightly over but I'm reluctant to touch the factory cal until absolutely certain. I'm happy with it.
As for your Ecowitt gauge... I own an Ecowitt gauge and it is fitted at my house in Perth, purchased from Amazon. I also compared it to a 4" Nylex gauge and found it reads way over. I applied a 0.65 multiplier at the Ecowitt console which produces a figure fairly close to the manual gauge. I'm not sure there is any mechanical calibration available on the Ecowitt device. Note most the rain in Perth is from cold fronts and pretty heavy when it comes (not often enough these days!).
I have a Davis VP2 located in Indonesia but purchased in Australia from the Davis Australian agent. I recently fitted the tipping spoon upgrade, the old one was the double tipping bucket. The tipping spoon was also purchased from the Davis Australia agent. I've compared measurements between the VP2 and a 4" opening diam Nylex manual gauge. The Nylex gauge is identical in design to the American CocoRAHS gauge, but it does not come with any calibration certification.
I compared readings from 29th Jan to 9th Feb; Davis 195.8mm, Nylex manual 186.7mm.
So in aggregate the Davis gauge reads 4.9% over.
The manual gauge is about 15 meters away from the Davis gauge and also the manual gauge is 4ft off the ground whereas the Davis is on the shed roof about 12ft off the ground.
With the new tipping spoon I've found the Davis reads over during heavy showers and reads slightly under during lighter rain. During the trial period we had one day of heavy rain and the Davis recorded 98.8mm whereas the manual gauge recorded 90.6mm. My aero cone inner surface is quite rough so water is likely getting caught up in the cone then flashing off during the light events. I think this has no effect during heavy events. I need to purchase a new cone (expensive in Indonesia due to import duties, will buy in Aust. another time). If the majority of the rain is light in your location then this may contribute to your under reading?
My next move is to mount the manual gauge next to the Davis gauge on top of the shed to do a better comparison. However in summary I feel the Davis gauge with the tipping spoon reads slightly over but I'm reluctant to touch the factory cal until absolutely certain. I'm happy with it.
As for your Ecowitt gauge... I own an Ecowitt gauge and it is fitted at my house in Perth, purchased from Amazon. I also compared it to a 4" Nylex gauge and found it reads way over. I applied a 0.65 multiplier at the Ecowitt console which produces a figure fairly close to the manual gauge. I'm not sure there is any mechanical calibration available on the Ecowitt device. Note most the rain in Perth is from cold fronts and pretty heavy when it comes (not often enough these days!).