Purpose: Follow the steps below to verify that the ETI NOAH IV rain gauge is correctly operating when calibration weights are applied.
Required Equipment/Tools: One rain gauge calibration kit including one 500 gram calibration weight, five 2 Kilo gram calibration weights, sensor cover, level, paper towels, and distilled water.
Reference: ETI
NOAH IV technical manual, Bob Larson (NADP) Data and Information Manager
1. At the main site computer note the DataView rainfall accumulation and down the “RAINFALL” channel.
2. Take the calibration weights, sensor cover, level and cleaning supplies out to the NOAH IV rain gauge.
3. Use the level and verify that the gauge is level – check in two directions North/South & East/West – note your readings in site log ticket.
4. If the gauge is out of level, level it and note your new readings in site log ticket.
5. Remove the black inlet orifice (black rim).
6. Install the collection chamber (bucket) lifting handle and carefully lift the bucket up and out of the gauge.
7. Remove the bucket handle, empty the bucket and clean.
8. Inspect the inside of the gauge for debris, insects, cobwebs, etc and clean as necessary.
9. Carefully put the bucket back in the gauge.
10. Verify the alignment of the infrared optic holes and that the one with the “V” notch in the top edge of the rim is next to the sensor marked with an “N” (the “N” will be on the outside of the gauge).
11. Carefully re-install the black rim.
12.
Reset the gauge by holding the reset
pushbutton for three seconds, the pushbutton can be found mounted in one of the
support legs at the bottom edge of the gauge.
13. At the main site computer verify that the gauge is reporting 0.00 inches for at least 2 minutes.
14. If the reading is not 0.00, reset the
gauge and check the reading again. If
you cannot get a zero reading contact the Field Tech or
15. At the gauge, install the sensor cover over the black top rim so that it hangs down enough to block the sensor holes in the bucket, carefully and gently set a 500-gram calibration weight into the bucket.
16. At the main site computer verify that the gauge reports the correct reading (see chart below) – it will take five minutes for the gauge to report this stable reading for each.
17. If the DataView reading is correct remove the sensor cover for at least one minute.
18. After at least one minute replace the sensor cover as stated before and carefully install the next calibration weight.
19. If the DataView reading is not correct, remove the weight(s), reset the gauge and repeat the test.
20. If you cannot get a good reading contact
the Field Tech or
21. Note all of your DataView readings in the TrackOps ticket.
22. Repeat steps 16 thru 20 using the additional calibration weights until you have all six weights in the bucket. Your DataView readings should be:
Step 1: 500 gram weight only: .61 ±.05 (.56 to .66)
Step 2: Add 2 Kilo gram weight: 3.03±.05 (2.97 to 3.08)
Step 3: Add 2 Kilo gram weight: 5.46±.05 (5.41 to 5.51)
Step 4: Add 2 Kilo gram weight: 7.88 ±.05 (7.83 to 7.93)
Step 5: Add 2 Kilo gram weight: 10.31 ±.05 (10.26 to 10.36)
Step 6: Add 2 Kilo gram weight: 12.73 ±.05 (12.67 to 12.78)
1. At the gauge, carefully remove the calibration weights and sensor cover.
2. Reset the gauge.
3. At the main site computer, verify that DataView reading is 0.00 and up the “RAINFALL” channel.
4. In TrackOps report all of your readings for: Beginning DataView rainfall reading, gauge level readings, zero after reset, and calibration weight readings for steps 1 through 6 and/or any problems encountered.