rain sensor

Tips, tricks and frequently asked questions
wopper
Posts: 53
Joined: 09 Mar 2014, 22:13

Re: rain sensor

Post by wopper » 26 Apr 2014, 10:38

We'll if i reset the data ( delete it via my.netatmo.com ) and empty 5 mm into the rain gauge it will display 1 mm.

Yes the gauge also displays the cumulative value which should be the same as what i put in the gauge via my analog meter.

So something is going wrong :D

1l2p
Posts: 80
Joined: 30 Nov 2012, 19:34

Re: rain sensor

Post by 1l2p » 26 Apr 2014, 12:01

gt1948 wrote:How did you mount to the strap? Screw size?
I think the screw thread is the standard for attaching cameras on pods: 1/4-20 UNC (1/4 inch diameter, 20 threads per inch)

TurboXXL
Posts: 9
Joined: 10 Nov 2012, 22:34

Re: rain sensor

Post by TurboXXL » 26 Apr 2014, 12:54

Can somebody please tell more on the accuracy of the data?

sainbel69
Posts: 26
Joined: 08 Nov 2013, 13:07
Location: Sain-Bel, France
Contact:

Re: rain sensor

Post by sainbel69 » 26 Apr 2014, 13:42

Installation done, results obtained will be compared with VP2.
No calibration done, I will start with the current one.

Image
Jerome
Données météo Sain-Bel (Rhone) http://www.meteo-sain-bel.fr/

1l2p
Posts: 80
Joined: 30 Nov 2012, 19:34

Re: rain sensor

Post by 1l2p » 26 Apr 2014, 15:13

Starting from the fact that the funnel is R = 6,25 cm inside radius. This corresponds to a surface of S = 122.72 cm2 (Pi x R x R).

If we add V = 100 cm3 of water (100 ml), we should get a raining height of V / S = 1,227 mm over the period . The sensor gave me 3,1 mm with the default calibration of 1,256 ml/topping.

Do you think this method is correct or am I doing wrong ?

DigitalMann
Posts: 48
Joined: 10 Apr 2014, 03:52

Re: rain sensor

Post by DigitalMann » 28 Apr 2014, 08:37

TurboXXL wrote:Oh, don't think that plastic will last very long under outdoor conditions...
We get hail quite often in the summer. I know it can't measure hail but do you think it can withstand a hailstorm?

manu5555
Posts: 9
Joined: 01 Dec 2013, 12:17

Re: rain sensor

Post by manu5555 » 30 Apr 2014, 12:22

1l2p wrote:Starting from the fact that the funnel is R = 6,25 cm inside radius. This corresponds to a surface of S = 122.72 cm2 (Pi x R x R).

If we add V = 100 cm3 of water (100 ml), we should get a raining height of V / S = 1,227 mm over the period . The sensor gave me 3,1 mm with the default calibration of 1,256 ml/topping.

Do you think this method is correct or am I doing wrong ?

I think you are wrong with you method:

you drop 100ml inside the captor equals 0,1L in a surface of 0,0625M*0,0625M*3,14= 0,012267M2

0,1L in 0,012267 M2
means 8,15L in 1 M2 (0,1/0,012267)


So if you drop 100ml in the sensor the result should be 8,15 mmm

wopper
Posts: 53
Joined: 09 Mar 2014, 22:13

Re: rain sensor

Post by wopper » 30 Apr 2014, 13:33

Hi manu5555

Well you are completely right! Got this calculation done last days and i was filling it up with 1 liters of water which should give me arround 82mm on the readings. From what i have seen so far is that the calibration value is a kind of not so reliable based on my tests.

Left the calibration value / right the readings. Putted 1 liters of dripping (so it took at least 45minutes to empty the 1 liter bottle) into the Rain Gauge.
1,36 98 mm
1,36 56 mm
1,25 60,9 mm
1,3 76,6 mm
1,31 70,4 m
2 83,1 mm

Thats strange because when i put 200ml of water into the rain gauge by hand and devided it by the tippings (formal method) it gives me a calibration value of 200/147 =1.36 Soi put the calibration on 2 for now.

Its now a rain day over here so i can start again on a sunny day.

Any other people which are facing calibration results which are good or bad?

1l2p
Posts: 80
Joined: 30 Nov 2012, 19:34

Re: rain sensor

Post by 1l2p » 30 Apr 2014, 20:18

manu5555 wrote:I think you are wrong with you method:
you drop 100ml inside the captor equals 0,1L in a surface of 0,0625M*0,0625M*3,14= 0,012267M2
0,1L in 0,012267 M2 means 8,15L in 1 M2 (0,1/0,012267)
So if you drop 100ml in the sensor the result should be 8,15 mmm
Thank you very much. I totally agree with you, I calculated S / V instead of V / S as I wrote :oops:. The theoretical value should be 8,15 mm !
I got 3,1mm from then sensor, so I will try to put the water drip by drip. I think I've been too fast...

wopper
Posts: 53
Joined: 09 Mar 2014, 22:13

Re: rain sensor

Post by wopper » 30 Apr 2014, 20:39

Yeah it could not handle " fast water" im interested in how many rain per mm it could handel at max.

If i let it drip it is most accurate and it gives the highest values, 1 liter should at least last 30-60 minutes to drip.

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