Analysis of a gas flow control system of KRISS in the pressure range from 1 Pa to 133 Pa

Gas flow and its measurement are vital in the process industry where most processes are carried out during dynamic gas flows. This work is concerned with flow analysis of various gases, including Ar, N2, and He, in the range from 1 Pa to 133 Pa for the newly developed flow control system at Korea Research Institute of Standards and Science (KRISS). For the chamber of this system, (a) the gas flow was first in the transitional region (0.01 < Kn < 0.5) which changed to the viscous region (Kn < 0.01) with increasing pressure and (b) the equilibrium time for the three gases were calculated to be 28 ∼ 12 min, 24 ∼ 10 min, and 10 ∼ 6 min, respectively. Similarly, the flow within the conductance-reducer in the by-pass line was first molecular (Kn > 0.5) and then shifted to transitional as the pressure was increased across its ends. The data obtained were specific for this system, but the trends for the characteristics of the flow control system may be useful to researchers in relevant fields.