HIGH DILUTION RATIO
PPM -> PPB
Description of the Application.
Standard dictates to measure the overall capacity of the photocatalyst in removing the nitrous oxide, NOx, using and air flow containing NO and NO2 (1ppmv) within an average test time of 5,0 h in lighting condition and with a flow rate of 1.5 L/min. The level of exhaust used is about 500 ppbv. Given the low stability and the difficulty to find gas test cylinder in such low concentrations, we decided to use standard Mass Flow Controller to reduce through mixing ultrapure air at 500 ppbv of NOx tanks as balance with standard cylinders with a concentration of 400 ppmv of NO and 400 ppmv of NO2. Although, a dynamic preparation of gas mix of this type and composition control of the mix itself with a Mass Flow Controller resulted mediocre due to the long response time and the high instability, for the long duration of the test (5h), in controlling low flow rate which, in time, led to inaccurate estimates of the efficiency of the photocatalyst and to the non reproducibility of standard test conditions. The using of the MCQ GB100 Series allowed to obtain the desired concentration within the photoreactor with a flow rate of 500 mL/min using ultrapure dry Air as balance gas and a NOx mix as solute.
Benefits and Savings.
A traditional method would require at least 2 mass flow controllers, an external control unit, a power supply, and a tubing system, plus a massive investment of time in pre-mixed ppb gas cylinders. This obsolete method would not neither solve the problem at its roots, because of a huge waste of time in gas delivering, and a substantial impossibility to diluite desired gas ratios with a certain stability. With MCQ Instruments, the Universita’ La Sapienza required only a single Gas Blender 100 Series device and its Software in Pro Version. The simple combination of these two factors has made possible an exponential number of experiments, reducing time, efforts, investments and collecting much more results. In pills:
HIGH GAS DILUTION RATIO
The Sapienza University of Rome (Italian: Sapienza – Università di Roma), also called simply Sapienza or the University of Rome, is a collegiate research university that is located in Rome, Italy. Formally known as Università degli Studi di Roma “La Sapienza“, it is one of the largest European universities by enrollments and one of the oldest in history, founded in 1303. The University is one of the most prestigious Italian universities, commonly ranking first in national rankings and in Southern Europe.
Most of the Italian ruling class studied at Sapienza. Sapienza educated numerous notable alumni, including many Nobel laureates, Presidents of the European Parliament and European Commissioners, heads of several nations, notable religious figures, scientists and astronauts. In September 2018, it was included in the top 100 of the QS World University Rankings Graduate Employability Ranking.