Rain Gage calibration

[StokesValleyWeather]

Hi,

I am building a new 1-wire station and need to recalibrate a WM918 rain gage fir WD. The rain gage has a 213mm dia funnel on top. I have worked out how to ajust the tipping bucket (if needed) and now need to work out how much each bucket tip is worth over the collection area if each bucket tip contails 8mls of water = 0.000 008 cubic meter.

Collection area=  1/2 * 213/1000² * pi = .03563m²

This is what I have worked out. mm of rail/bucket tip= 0.000 008³/0.03563m² = 0.000 22453m or .22453mm of rain per bucket tip.

Can some one please verify my calculations or tell me how I should work the calibration out.

Many thanks.

[niko]

New tip size = original tip size *  (old collection area/new collection area)

[StokesValleyWeather]

Niko,
Thanks. Looks like my current gage is under reading based on below:

So if my existing rain gage is 4" or 100mm dia the collection area is .007854m² and 1mm of rain was to fall this will equal .000007854m³ this equals 7.854mls. (its currently tipping when 8mls is in each bucket). Based on the current calibration of my rain gage it is slightly under reading.

Thanks.

Regards
Derek.
Stokes Valley Weather.

[niko]

You need to run a quantity of water through there so that you get a result averaged over a significant number of tips.

[StokesValleyWeather]

Hi, thanks niko, will do that.

Regards
Derek
Stokes Valley Weather.