Senseair K33 BLG, ELG CO2 Sensor tested
A university study has found the SenseAir K-33 BLG 30% CO2 + RH/T and K-33 ELG 1% CO2 + RH/T data-logging environmental sensors gave similar results to a Vaisala CO2 Probe in both testing and real-world experiments.
The study was conducted by a team of Environmental Engineering Researchers from the University of California, Merced. They were looking for a lower cost alternative to the Vaisala GMP343 Probe, a well-known brand of environmental sensor. Their goal was to develop a proof-of-concept for low-cost tools for long-term measurement and data logging of CO2 concentrations and fluxes in terrestrial ecosystems.
In addition to costing less than 1/10 the price of a Vaisala Probe, the SenseAir sensors have the advantage of including on-board temperature and relative humidity sensors, as well as built-in memory for data logging. Both the K-33 ELG 1% CO2 and K-33 BLG 30% CO2 sensors can collect up to 5,400 time-stamped data points in internal memory for later download. In addition, the SenseAir sensors can be powered by batteries in the field.
The first phase of the project was to calibrate the SenseAir sensors against a benchmark instrument, the LI-COR, Inc. LI-6400 gas analyzer. Both sensors tracked favorably at higher CO2 levels, although the wider range of the K-33 BLG 30% sensor was less accurate below 1,500ppm.
The second phase was to test the sensors on leaf cutter ant next vents. The K-33 BLG point system yielded comparable spatial and temporal patterns and slightly higher CO2 concentrations in comparison with a Vaisala GMP343 probe.
According to the study, their results provided “proof-of-concept for the use of SenseAir sensors in low-cost, portable CO2 sensing systems to enable terrestrial ecologists to substantially improve the characterization of CO2 fluxes and concentrations in heterogeneous environments.”
Long-term measurement of the natural terrestrial carbon cycle can provide additional data to scientists who want to further our understanding of the global carbon cycle.
The study was published in the November, 2015 issue of Methods in Ecology and Evolution Journal by the British Ecological Society. You can read the entire study online here.
In a side-by-side comparison of low-cost NDIR sensors to measure outdoor carbon dioxide levels, the SenseAir K30 Sensor was selected as the most accurate over the Vaisala CMM222C, ELT Company S100, Korean Digital Company (KCD) AN100 and GE Sensing T6615 CO2 Sensors.
The detailed comparison was published in the article "Comparison of the Characteristics of Small Commercial NDIR CO2 Sensor Models and Development of a Portable CO2 Measurement Device" in the MDPI Open Access Journals Platform.
The authors wrote the article as the result of a study to determine if low cost NDIR CO2 sensors could be easily calibrated and were accurate enough to use in a low-cost portable device designed to record carbon dioxide levels from many locations in a large urban environment over time.
To conduct their experiment, the team purchased three copies of five different commercially available NDIR sensors and tested them in a classroom. In addition, they tested each sensor against four samples of standard gas with different CO2 concentrations.
According to their results, "The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO2 measurement device."