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Weather Station Hardware => Other Weather Station Hardware => Topic started by: miraculon on September 14, 2015, 04:26:48 PM
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I made a crude calibrator of sorts to get a basic check of my NovaLynx. In this thread (http://www.wxforum.net/index.php?topic=26463.msg263539#msg263539), comparing the VP2, NovaLynx and two CoCoRaHS-type 4" gauges I was seeing higher amounts on the NovaLynx.
The smallest drill I had was a 1/16". I bought a 1½ x 3" PVC reducer, a plug with a flat bottom and a brass square plug. The brass wasn't thick enough to achieve the nozzle length of the actual calibrator, but it was the best that I could do. The brass fitting was forcibly "tapped" into the PVC, but it was leak tight and worked well. I added three vinyl bumpers to try to protect the gauge funnel finish.
Here is the upside-down orifice funnel thing that I made up:
(http://miraculon.net/novalynx/WP_20150914_006.jpg)
Here are three beakers ready to go into the funnel/orifice. There is a 1000mL, 50mL and a 10mL filled and ready to pour at 900mL, 45mL and 1mL. The 10mL was also used to get to the "last tip" after the 946mL was poured. Conveniently, it also has a reversed scale from 10mL set to zero.
(http://miraculon.net/novalynx/WP_20150914_003.jpg)
Here is the funnel/orifice in the NovaLynx. I will say that the flow rate was far more consistent than I could achieve pouring by hand.
(http://miraculon.net/novalynx/WP_20150914_002.jpg)
The results were pretty close to what they should have been. My numbers looked more like the chart says for the 1/32nd inch orifice. For the 1/16th inch, the 946mL should deliver 1.15 inches.
My results were consistently close to 1.19 inches.
Here is my Excel spreadsheet. Note that I subtracted the previous amount since my gauge totals were accumulating across the three runs.
| Trial | Beaker1 | Beaker2 | Beaker3 | Last Tip | Total | Gauge | Target | Delta | Percent |
| 1 | 900 | 45 | 1 | 5.5 | 951.5 | 1.19 | 1.15 | 0.04 | 3% |
| 2 | 900 | 45 | 1 | 7.5 | 953.5 | 1.19 | 1.15 | 0.04 | 3% |
| 3 | 900 | 45 | 1 | 7.0 | 953.0 | 1.20 | 1.15 | 0.05 | 4% |
To explain:
Trial=run number
Beaker1=1000mL big one fill point
Beaker2=50mL fill point
Beaker3=10mL 1mL fill to make up to 946mL
Last Tip=amount used in 10mL just after final tip occurs.
Total=add up beakers
Gauge=amount read back via station
Target=amount it should have been for 1/16" orifice and 946mL of water.
Delta=difference from target
Percent=delta/target %
It seems to be pretty close to the 2% specification. Despite seeing comparative readings being higher on the NovaLynx, the calibration looks OK to me. (especially considering the crudeness of the equipment)
I think that I will "leave it alone" and not play with the stop adjustments... :-k
Greg H.