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Title: eosGP comparison - 11/2023
Date:2023-11-16
Data File:
Refers to:GP20160012,GP20160042,GP20160117,GP20170028,GP20200089,GP20140026

I tested the remaining eosGP found in the lab. The sensor at GT has weird data, so I was hoping to find a good one that I could swap in. We found 6 old eosGP sensors, 2 that were removed from the Delta and 4 that were removed in summer 2022 from the Vaira soil CO2 profiles.

 

sn Last location Date Removed Reason for removal Range of CO2 Data column Calibration results
GP20160012 VR 2022-05-10 CO2 profiles obsolete 0-1.2% CO2_1 Bad sensor
GP20160042 VR 2022-05-10 CO2 profiles obsolete 0-1.2% CO2_2 Bad sensor
GP20160117 VR 2022-05-10 CO2 profiles obsolete 0-1.2% CO2_3 See calib eqn below
GP20170028 VR 2022-05-10 CO2 profiles obsolete 0-1.2% CO2_4 See calib eqn below
GP20200089 GT 2023-03-23 Bad data 0-2.4% CO2_5 Bad sensor
GP20140026 WP 2021-02-04 Noisy data 0-2.4% CO2_6 See calib eqn below

 

I wired all 6 sensors to a CR1000 sn 4017, scanning every 10sec and saving every 1min. Joe stuffed all of the sensors into a plastic container with a lid. The container also contained a 12V fan to circulate the air inside the container and a swagelock tube fitting. I ran 1% CO2 air into the container until the values stabilized. I then ran zero air into the container until the values stabilized. I used these values to calculate a calibration equation for CO2 for the three reasonable sensors. The other three sensors were obviously bad. I did not calibrate for temperature. All sensors have a temperature range of -20 to 50C.

sn Range of CO2 Avg mV at 1% Std Dev at 1% Avg mV at 0% Std Dev at 0% Y=%, x=mV
GP20160117 0-1.2% 3043 11.63 11 0.53 Y=(1/3022)*x+11
GP20170028 0-1.2% 4654 10.43 249 25.05 Y=(1/4405)*x+249
GP20140026 0-2.4% 1907 9.34 19 8.24 Y=(1/1888)*x+19