VARIATION OF CO_2 CONCENTRATION OF AIR AT MASS STANDARD LABORATORY OF KRISS

摘要

The CO_2 concentration of air in the mass laboratory of KRISS were measured by the use of a infrared gas analyser during the time of Sep.19 to Dec. 24 in 1988 and June 7 to June 24 in 1994. The results show that the CO_2 concentrations varies from 350 ppm to 550 ppm. For a working day, the variation characteristics of the CO_2 concentration shows a trend of increment in the morning, decrement in lunch time, increment in the afternoon after lunch time, and decrement after the closing hour. It takes about 12 hours for the CO_2 concentration of the room to arrive at that of ambient air after the office hour. The difference between the low and high of the CO_2 concentrations varies like as 61 ppm in June, 89 ppm in Sep., 103 ppm in Oct., 152 ppm in Nov., and 148 ppm in Dec. A theoretical approach to a typical data shows that a space time for a decrement after closing hour was a 3.57 hours and that dC/dt = 26 ppm/hr for the increment due to the effects of people in the morning 9 to 10 o'clock. The CO_2 concentration of air can be measured with an uncertainty of 5 ppm, affecting 2 × 10~(-10) kg for 80 cm~3, when only countering span drift of ±1 %. If the international average CO_2 concentration value is directly used without measurement, then an uncertainty of 100 ppm, affecting 4×10~(-8) kg for 80 cm~3, is estimated in KRISS mass laboratory.