Calibration history for LI-7500 #75H-2176

Calibration Date:2023-11-03
Last calibration: 2023-07-20
Calibrated by: Joe
SS=101 SDM= DAC1= DAC2=
AIU sn AIU-1039 Pressure A0=58.372, A1=15.4
Ambient P=100.8kPa Tair=25.1C, Tdew=9.77C
Zero Air at 700psi, AMP CA04119 524.77ppm 800psi Tdewspan=20
CO2 zero 0.868 -> 0.8678 Offset: -0.77ppm
CO2 span 1.0095 -> 1.0116 Offset: -1.47ppm
H2O zero 0.8525 -> 0.8552 Offset: 15.8mmol/m3
H2O span 0.9124 -> 0.9231 Offset: -0.26C
Notes: Using loaner AMP 7550 sn AIU-1039. Dewpoint generator had low flow; fixed one of the condenser tubing which had a crack and flow was back to normal. Vertical orientation.

Calibration Date:2023-07-20
Last calibration: 2023-03-29
Calibrated by: Daphne
SS=100 SDM= DAC1= DAC2=
AIU sn AIU-1569 Pressure A0=58.004, A1=15.479
Ambient P=100.6kPa Tair=C, Tdew=13.45C
Zero Air at 1000psi, AMP CA04119 524.77ppm 925psi Tdewspan=16
CO2 zero 0.8679 -> 0.868 Offset: 0.3ppm
CO2 span 1.013 -> 1.0095 Offset: 2.43ppm
H2O zero 0.8562 -> 0.8525 Offset: -21.4mmol/m3
H2O span 0.9316 -> 0.9124 Offset: 0.43C
Notes: Slightly larger H2O zero and span offset than usual. Vertical orientation.

Calibration Date:2023-03-29
Last calibration: 2022-12-05
Calibrated by: Daphne
SS=100 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=99.8kPa Tair=19.16C, Tdew=7.7C
Zero Air at 1300psi, AMP CA04119 524.77ppm 1150psi Tdewspan=16
CO2 zero 0.8678 -> 0.8679 Offset: 0.37ppm
CO2 span 1.0144 -> 1.013 Offset: 0.93ppm
H2O zero 0.8553 -> 0.8562 Offset: 5.2mmol/m3
H2O span 0.9281 -> 0.9316 Offset: -0.08C
Notes:

Calibration Date:2022-12-05
Last calibration: 2022-08-23
Calibrated by: Joe Verfaillie
SS=101 SDM=0 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.6kPa Tair=20.5C, Tdew=9.85C
Zero Air at 1700psi, AMP CA04119 524.77ppm 1325psi Tdewspan=16
CO2 zero 0.8678 -> 0.8678 Offset: 0ppm
CO2 span 1.0008 -> 1.0144 Offset: -9.57ppm
H2O zero 0.8537 -> 0.8553 Offset: 9.8mmol/m3
H2O span 0.923 -> 0.9281 Offset: -0.12C
Notes: Large offset in CO2 span. But this largely undoes some similar previous increases. Calibrated at the same time sn 2180 showed a similar CO2 span offset. This calibration was using 7550 box 0674 instead of the AMP loaner but I don't see how that should effect only CO2 span. Going to go with it.

Calibration Date:2022-08-23
Last calibration: 2022-04-19
Calibrated by: Daphne
SS=96 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.1kPa Tair=24.01C, Tdew=14.55C
Zero Air at 300psi, AMP CA04119 524.77ppm 1400psi Tdewspan=20
CO2 zero 0.867 -> 0.8678 Offset: 3.56ppm
CO2 span 1.0081 -> 1.0008 Offset: 4.59ppm
H2O zero 0.8557 -> 0.8537 Offset: -11.9mmol/m3
H2O span 0.9228 -> 0.923 Offset: -0.02C
Notes: Calibration using AMP loaner 7550 sn AIU-1039

Calibration Date:2022-04-19
Last calibration: 2021-12-16
Calibrated by: Daphne
SS=101 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.9kPa Tair=24.5C, Tdew=10.5C
Zero Air at 700psi, AMP CA04119 524.77ppm 1600psi Tdewspan=20
CO2 zero 0.867 -> 0.867 Offset: 0.13ppm
CO2 span 1.0045 -> 1.0081 Offset: -2.65ppm
H2O zero 0.8546 -> 0.8557 Offset: 6.7mmol/m3
H2O span 0.8249 -> 0.9228 Offset: 0.05C
Notes: Surprisingly large change in H2OSpan's coefficient despite a small offset. Maybe double check this again before deploying.

Calibration Date:2021-12-16
Last calibration: 2021-09-21
Calibrated by: Daphne
SS=99 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.8kPa Tair=23.2C, Tdew=7.8C
Zero Air at 1075psi, AMP CA04119 524.77ppm 1650psi Tdewspan=20
CO2 zero 0.867 -> 0.867 Offset: 0.04ppm
CO2 span 1.0023 -> 1.0045 Offset: -1.43ppm
H2O zero 0.8526 -> 0.8546 Offset: 12.2mmol/m3
H2O span 0.9091 -> 0.8249 Offset: -0.39C
Notes: Realized after H2O span that hood was only partly covering lens. Checked the zero again and it was off, so re-did the whole calibration again. These are the coefficients from this second calibration.

Calibration Date:2021-09-21
Last calibration: 2021-06-07
Calibrated by: Daphne
SS=100 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.6kPa Tair=29C, Tdew=11.4C
Zero Air at 1550psi, AMP CA04119 524.77ppm 1700psi Tdewspan=20
CO2 zero 0.8673 -> 0.867 Offset: -1.56ppm
CO2 span 1.0067 -> 1.0023 Offset: 3.07ppm
H2O zero 0.8536 -> 0.8526 Offset: -5.5mmol/m3
H2O span 0.9148 -> 0.9091 Offset: 0.14C
Notes:

Calibration Date:2021-06-07
Last calibration: 2021-03-01
Calibrated by: Daphne
SS=100 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.1kPa Tair=22.3C, Tdew=8.7C
Zero Air at 200psi, AMP CA04119 524.77ppm 1700psi Tdewspan=16
CO2 zero 0.8671 -> 0.8673 Offset: 0.96ppm
CO2 span 1 -> 1.0067 Offset: -4.75ppm
H2O zero 0.8524 -> 0.8536 Offset: 7mmol/m3
H2O span 0.9092 -> 0.9148 Offset: -0.13C
Notes:

Calibration Date:2021-03-01
Last calibration: 2020-12-02
Calibrated by: joe
SS=103 SDM=0 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.4kPa Tair=22.9C, Tdew=4.6C
Zero Air at 450psi, AMP CA04396 408.97ppm 250psi Tdewspan=20
CO2 zero 0.8673 -> 0.8671 Offset: -0.25ppm
CO2 span 1.009 -> 1 Offset: 2.53ppm
H2O zero 0.8531 -> 0.8524 Offset: -1.3mmol/m3
H2O span 0.9238 -> 0.9092 Offset: 0.37C
Notes: Flow rates were larger than usual - 2lpm instead of 2cfpm.

Calibration Date:2020-12-02
Last calibration: 2020-08-25
Calibrated by: Daphne
SS=101 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.8kPa Tair=25.1C, Tdew=3.3C
Zero Air at 450psi, AMP CA4396 408.97ppm 300psi Tdewspan=20
CO2 zero 0.8671 -> 0.8673 Offset: 0.59ppm
CO2 span 1.0055 -> 1.009 Offset: -1.94ppm
H2O zero 0.8526 -> 0.8531 Offset: 3mmol/m3
H2O span 0.9246 -> 0.9238 Offset: 0.02C
Notes:

Calibration Date:2020-08-25
Last calibration: 2020-05-13
Calibrated by: Joe Verfaillie
SS=101 SDM=0 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.2kPa Tair=23.8C, Tdew=14.7C
Zero Air at 700psi, AMP CA04396 408.97ppm 450psi Tdewspan=20
CO2 zero 0.8672 -> 0.8671 Offset: -0.1ppm
CO2 span 1.0081 -> 1.0055 Offset: 1.33ppm
H2O zero 0.8521 -> 0.8526 Offset: 2.9mmol/m3
H2O span 0.9159 -> 0.9246 Offset: -0.2C
Notes:

Calibration Date:2020-05-13
Last calibration: 2019-11-13
Calibrated by: Daphne
SS=100 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.6kPa Tair=21.6C, Tdew=11.9C
Zero Air at 725psi, AMP CA4396 408.97ppm 550psi Tdewspan=16
CO2 zero 0.8675 -> 0.8672 Offset: -1.42ppm
CO2 span 1.0072 -> 1.0081 Offset: -0.52ppm
H2O zero 0.852 -> 0.8521 Offset: 0.8mmol/m3
H2O span 0.9123 -> 0.9159 Offset: -0.09C
Notes:

Calibration Date:2019-11-13
Last calibration: 2019-07-24
Calibrated by:
SS=100 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.5kPa Tair=25.6C, Tdew=11.4C
Zero Air at 900psi, AMP CA4396 408.97ppm 650psi Tdewspan=16
CO2 zero 0.8672 -> 0.8675 Offset: 1.36ppm
CO2 span 1.0061 -> 1.0072 Offset: -0.67ppm
H2O zero 0.8521 -> 0.852 Offset: -1mmol/m3
H2O span 0.9182 -> 0.9123 Offset: 0.13C
Notes: Did an initial calibration yesterday using config file 2019-07-24, but it had a large H2O zero offset (-35.7 mmol/m3) and H2O span offset (1.53C). Today I did another calibration, again from the config file 2019-07-24. Today the H2O offset/span seem ok, so not sure what was happening yesterday. I saved today's new config file and deleted yesterday's to avoid confusion.

Calibration Date:2019-07-24
Last calibration: 2019-01-02
Calibrated by:
SS=102 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.5kPa Tair=26.1C, Tdew=14.5C
Zero Air at 1000psi, AMP Air 408.97ppm 800psi Tdewspan=20
CO2 zero 0.8676 -> 0.8672 Offset: -2.14ppm
CO2 span 1.0114 -> 1.0061 Offset: 2.7ppm
H2O zero 0.8525 -> 0.8521 Offset: -2.4mmol/m3
H2O span 0.8206 -> 0.9182 Offset: 0.05C
Notes: When SS was 102.0, I reset it to 100.

Calibration Date:2019-01-02
Last calibration: 2018-07-10
Calibrated by:
SS=102 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=101.2kPa Tair=20.5C, Tdew=3.3C
Zero Air at 1250psi, AMP Air 408.97ppm 850psi Tdewspan=16
CO2 zero 0.8671 -> 0.8676 Offset: 2.45ppm
CO2 span 1.0029 -> 1.0114 Offset: -4.48ppm
H2O zero 0.848 -> 0.8525 Offset: 27.5mmol/m3
H2O span 0.9088 -> 0.8206 Offset: -0.27C
Notes:

Calibration Date:2018-07-10
Last calibration: 2018-03-05
Calibrated by:
SS=101 SDM= DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.5kPa Tair=27C, Tdew=13.3C
Zero Air at 175psi, LBL Air 408.97ppm 1400psi Tdewspan=16
CO2 zero 0.8679 -> 0.8671 Offset: -3.65ppm
CO2 span 1.0057 -> 1.0029 Offset: 1.23ppm
H2O zero 0.8486 -> 0.848 Offset: -3.4mmol/m3
H2O span 0.9112 -> 0.9088 Offset: 0.05C
Notes:

Calibration Date:2018-03-05
Last calibration: 2018-02-05
Calibrated by:
SS=101 SDM=0 DAC1=0 DAC2=0
AIU sn AIU- Pressure A0=, A1=
Ambient P=101.2kPa Tair=23.3C, Tdew=4.2C
Zero Air at 100psi, LBL Air 408.97ppm 1700psi Tdewspan=16
CO2 zero 0.8674 -> 0.8679 Offset: 2.12ppm
CO2 span 1.0032 -> 1.0057 Offset: -1.52ppm
H2O zero 0.851 -> 0.8486 Offset: -15.8mmol/m3
H2O span 1.0142 -> 0.9112 Offset: 2.31C
Notes: First calib in the lab since Licor factory repair/calib. The H2O zero and span have large offsets because the Licor factory H2O calibration station failed. Our dewpoint generator results matched with Patty's dewpoint generator.

Calibration Date:2018-02-05
Last calibration: 2017-11-09
Calibrated by:
SS=0 SDM=0 DAC1=0 DAC2=0
AIU sn AIU- Pressure A0=, A1=
Ambient P=0kPa Tair=0C, Tdew=0C
Licor Factory at 0psi, Licor Factory 750ppm 0psi Tdewspan=12
CO2 zero 0.869 -> 0.8674 Offset: 0ppm
CO2 span 1.0225 -> 1.0032 Offset: 0ppm
H2O zero 0.857 -> 0.851 Offset: 0mmol/m3
H2O span 1.0047 -> 1.0142 Offset: 0C
Notes: Zero/Span set on 06 Feb 2018 at Li-cor Factory. CX=40242.3, WX=40527.3

Calibration Date:2017-11-09
Last calibration: 2017-06-12
Calibrated by:
SS=90 SDM=0 DAC1=0 DAC2=0
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.6kPa Tair=22.5C, Tdew=12.2C
Zero Air at 400psi, LBL Air 408.97ppm 1800psi Tdewspan=16
CO2 zero 0.869 -> 0.869 Offset: 0ppm
CO2 span 1.016 -> 1.0225 Offset: -3.37ppm
H2O zero 0.8572 -> 0.857 Offset: -1.3mmol/m3
H2O span 1.0022 -> 1.0047 Offset: -0.06C
Notes: Calibrated on AIU-0674 (version 8.5.0)

Calibration Date:2017-06-12
Last calibration: 2017-03-07
Calibrated by:
SS=90 SDM=0 DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.4kPa Tair=19.8C, Tdew=8.83C
Zero Air at 1500psi, NOAA Air 402.69ppm 1600psi Tdewspan=16
CO2 zero 0.8691 -> 0.869 Offset: -0.41ppm
CO2 span 1.0195 -> 1.016 Offset: 1.77ppm
H2O zero 0.8561 -> 0.8572 Offset: 5.9mmol/m3
H2O span 1.0102 -> 1.0022 Offset: 0.18C
Notes:

Calibration Date:2017-03-07
Last calibration: 2016-10-25
Calibrated by:
SS=92 SDM=0 DAC1=-- DAC2=--
AIU sn AIU- Pressure A0=, A1=
Ambient P=101.1kPa Tair=21.5C, Tdew=0C
Zero Air at 1700psi, God Air 421.22ppm 375psi Tdewspan=16.01
CO2 zero 0.8689 -> 0.8691 Offset: 0.83ppm
CO2 span 1.0176 -> 1.0195 Offset: -1.04ppm
H2O zero 0.8563 -> 0.8561 Offset: -0.7mmol/m3
H2O span 1.0134 -> 1.0102 Offset: -0.04C
Notes:

Calibration Date:2016-10-25
Last calibration: 2016-06-03
Calibrated by:
SS=91 SDM=6 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.28kPa Tair=20.11C, Tdew=12.3C
Zero Air at 400psi, God CO2 421.22ppm 450psi Tdewspan=16.01
CO2 zero 0.8688 -> 0.8689 Offset: 0.22ppm
CO2 span 1.0175 -> 1.0176 Offset: -0.12ppm
H2O zero 0.8571 -> 0.8563 Offset: -4.9mmol/m3
H2O span 1.0281 -> 1.0134 Offset: 0.31C
Notes:

Calibration Date:2016-06-03
Last calibration: 2016-02-22
Calibrated by:
SS=91 SDM=6 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.05kPa Tair=24.56C, Tdew=12.8C
Zero Air at 500psi, God CO2 421.22ppm 500psi Tdewspan=15.08
CO2 zero 0.8692 -> 0.8688 Offset: -1.68ppm
CO2 span 1.0205 -> 1.0175 Offset: 1.63ppm
H2O zero 0.8564 -> 0.8571 Offset: 4.3mmol/m3
H2O span 1.0136 -> 1.0281 Offset: -0.3C
Notes: The spars were very dirty with clinging dust.

Calibration Date:2016-02-22
Last calibration: 2015-10-28
Calibrated by:
SS=91 SDM=6 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.94kPa Tair=23.4C, Tdew=8.96C
Zero Air at 650psi, God CO2 421.22ppm 700psi Tdewspan=11.09
CO2 zero 0.8691 -> 0.8692 Offset: 0.55ppm
CO2 span 1.0177 -> 1.0205 Offset: -1.47ppm
H2O zero 0.8565 -> 0.8564 Offset: -0.6mmol/m3
H2O span 1.0086 -> 1.0136 Offset: -0.1C
Notes:

Calibration Date:2015-10-28
Last calibration: 2015-05-05
Calibrated by:
SS=91 SDM=6 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.3kPa Tair=21.39C, Tdew=14.08C
Zero Air at 750psi, God CO2 421.22ppm 800psi Tdewspan=11.08
CO2 zero 0.8692 -> 0.8691 Offset: -0.61ppm
CO2 span 1.0216 -> 1.0177 Offset: 2.1ppm
H2O zero 0.8562 -> 0.8565 Offset: 1.5mmol/m3
H2O span 1.0239 -> 1.0086 Offset: 0.3C
Notes:

Calibration Date:2015-05-05
Last calibration: 2015-05-05
Calibrated by:
SS=91 SDM=1 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.12kPa Tair=14.62C, Tdew=8.08C
Zero Air at 850psi, God CO2 421.22ppm 1100psi Tdewspan=11.08
CO2 zero 0.8691 -> 0.8692 Offset: 0.38ppm
CO2 span 1.0215 -> 1.0216 Offset: 0ppm
H2O zero 0.8559 -> 0.8562 Offset: 1.7mmol/m3
H2O span 1.0099 -> 1.0239 Offset: -0.27C
Notes:

Calibration Date:2015-01-06
Last calibration: 2014-09-23
Calibrated by:
SS=90 SDM=1 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=101.28kPa Tair=22.82C, Tdew=5.69C
Zero Air at 950psi, God CO2 421.22ppm 1300psi Tdewspan=15.95
CO2 zero 0.8685 -> 0.8691 Offset: 2.56ppm
CO2 span 1.0145 -> 1.0215 Offset: -3.66ppm
H2O zero 0.8547 -> 0.8559 Offset: 6.6mmol/m3
H2O span 1.0075 -> 1.0099 Offset: -0.05C
Notes:

Calibration Date:2014-09-23
Last calibration: 2014-03-17
Calibrated by:
SS=89 SDM=1 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.22kPa Tair=26.52C, Tdew=16.19C
Zero Air at 1050psi, God CO2 421.22ppm 1350psi Tdewspan=15.8
CO2 zero 0.8687 -> 0.8685 Offset: -0.73ppm
CO2 span 1.0113 -> 1.0145 Offset: -1.74ppm
H2O zero 0.8531 -> 0.8547 Offset: 8.8mmol/m3
H2O span 0.9904 -> 1.0075 Offset: -0.37C
Notes:

Calibration Date:2014-03-17
Last calibration: 2013-08-27
Calibrated by: Joe Verfaillie
SS=88 SDM=1 DAC1=- DAC2=-
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.31kPa Tair=24.17C, Tdew=0.47C
Zero Air at 1400psi, God CO2 421.22ppm 1550psi Tdewspan=15.22
CO2 zero 0.8685 -> 0.8687 Offset: 1.42ppm
CO2 span 1.0099 -> 1.0113 Offset: -0.84ppm
H2O zero 0.8539 -> 0.8531 Offset: 1.4mmol/m3
H2O span 1 -> 0.9904 Offset: 0.49C
Notes: Calibrated by Joe. Initially calibrated on March 12th but had very large offsets. I discovered that very small changes in SS caused by the hood (~4%) caused about 50ppm changes in CO2. A second calibration on the 17th was much better.

Calibration Date:2013-08-27
Last calibration: 2013-05-02
Calibrated by:
SS=87 SDM=1 DAC1=na DAC2=na
AIU sn AIU- Pressure A0=, A1=
Ambient P=99.84kPa Tair=26.53C, Tdew=13.56C
Zero Air at 1700psi, God CO2 421.22ppm 1600psi Tdewspan=15.18
CO2 zero 0.8676 -> 0.8685 Offset: 3.78ppm
CO2 span 1.0038 -> 1.0099 Offset: -3.34ppm
H2O zero 0.8539 -> 0.8539 Offset: 0mmol/m3
H2O span 0.9906 -> 1 Offset: -0.2C
Notes:

Calibration Date:2013-04-26
Last calibration: 2013-02-05
Calibrated by:
SS=0 SDM=1 DAC1=none DAC2=none
AIU sn AIU- Pressure A0=, A1=
Ambient P=0kPa Tair=0C, Tdew=0C
Zero air at 1700psi, CO2 in air 392.3ppm 0psi Tdewspan=15.04
CO2 zero 0.8676 -> 0.8676 Offset: 1ppm
CO2 span 1.0038 -> 1.0038 Offset: -4.7ppm
H2O zero 0.8539 -> 0.8539 Offset: 3.8mmol/m3
H2O span 0.9906 -> 0.9906 Offset: 0.42C
Notes: Last calibration was done at factory. I felt that the offsets were small enough that I did not recalibrate at this time.

Calibration Date:2013-02-05
Last calibration: 2012-08-29
Calibrated by:
SS=0 SDM=1 DAC1=none DAC2=none
AIU sn AIU- Pressure A0=, A1=
Ambient P=0kPa Tair=0C, Tdew=0C
at 0psi, 745.6ppm 0psi Tdewspan=12
CO2 zero 0.8694 -> 0.8676 Offset: 0ppm
CO2 span 1.0152 -> 1.0038 Offset: 0ppm
H2O zero 0.8534 -> 0.8539 Offset: 0mmol/m3
H2O span 0.9979 -> 0.9906 Offset: 0C
Notes: Factory calibration

Calibration Date:2012-08-29
Last calibration: 2012-01-27
Calibrated by:
SS=44 SDM=6 DAC1= DAC2=
AIU sn AIU- Pressure A0=, A1=
Ambient P=100.32kPa Tair=26.67C, Tdew=13.58C
Zero air at 1800psi, CO2 in air 398.9ppm 2000psi Tdewspan=15.08
CO2 zero 0.8691 -> 0.8694 Offset: 1.4ppm
CO2 span 1.0076 -> 1.0152 Offset: -3.8ppm
H2O zero 0.8509 -> 0.8534 Offset: 14.3mmol/m3
H2O span 0.9947 -> 0.9979 Offset: 0C
Notes: This IRGA seemed to be reading low in the field but no major offset seen in calibration. First lab calibration since receiving this instrument.