Study of water vapor pressure equilibration in a vacuum system

Non-stationary volume-adsorption model for pumping of vacuum chambers

“…where d and m are coefficients of the Frendlich adsorption isotherm equation for water at 298К, pm is limiting pressure of the pump, Pa; p1 is initial pressure, Pa; v=V/S, s; f = F/S, s•m -1 ; V is the chamber volume, m 3 ; F is the area of the internal surface of the chamber, m 2 ; S is efficient rate of the chamber pumping expressed in m 3 /s according to the approximation (7). The first term in (10) denotes the pumping time of water vapors, located in the chamber volume, and the second term is for the internal surface.…”

“…The adsorbed gas, which is energetically bound to the surface, is pumped out more slowly than the gas in the chamber volume. With a high vacuum, the pumping time of the vacuum chamber is almost completely determined by the pumping time of adsorbed gases [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. For large vacuum installations, for example International Thermonuclear Experimental Reactor (ITER), when choosing pumping means by specifying the pumping time, you can reduce the safety factor and get a significant economic effect.…”

“…Adsorbed gases mainly consist of water vapors absorbed on the walls of vacuum chambers during their depressurization [1][2][3][4][5][6][7][8][9][10][11][12]. Oils and organic compounds with a high vapor pressure at room temperature can also make a significant contribution to the total amount of adsorbed gas.…”