VACUUM Vacuum Pump Sizing To determine the vacuum pump size which is designated in cubic feet per minute (CFM), the following information is needed: V = The volume of the tank(s) or vacuum chamber in cubic feet T = The time required to achieve a specific vacuum level in minutes F = A pump down factor for the specific vacuum pump which relates to the vacuum level required for the process The formula for determining the vacuum pump size(S) is as follows: S = V x F T To determine the volume of standard tanks provided by Liquid Control, refer to the following chart: Tank Size Volume 3 Liter 0.11 cubic feet 5 Liter 0.18 cubic feet 2 Gallon 0.27 cubic feet 5 Gallon 0.67 cubic feet 10 Gallon 1.34 cubic feet 15 Gallon 2.00 cubic feet 30 Gallon 4.00 cubic feet 60 Gallon 8.00 cubic feet To determine the pump down factor, locate the desired vacuum level on the vertical axis. Then find where this intersects on the curve(s) and go straight down to the horizontal axis to find the pump down factor (F). Note: This graph is for a specific manufacturer of vacuum pumps and can vary for other types of vacuum pumps. For reference only. Vacuum Conversion Examples What size vacuum pump is required for degassing a 30 gallon tank of material at a vacuum level of 10 Torr with the time required to achieve that vacuum level in the tank being 2 minutes? S = V x F T S = 4.0 x 5 S = 10 CFM (minimum vacuum pump size) Note: The time required to thoroughly degas the material is dependent on the amount of air in the material, the viscosity of the material, the design of the agitation and/or recirculation system, and many other variables. The pump sizing above only considers the time required to achieve a certain vacuum level. How long will it take for a 6 CFM vacuum pump to achieve a I Torr vacuum level in a 5 gallon tank? S =   V x F or   T = V x F   T S T = 0.67 x 7 6 S = 0.78 minutes Note: This assumes no vacuum leaks in the tank. What size vacuum pump is required for achieving a I Torr vacuum level within I minute in a 2'x 2'x 2' vacuum chamber? S = V x F T S = 8 x 7 1 S = 56 CFM (minimum vacuum pump size) Vacuum Pump Sizing Torr or MM Mercury Micron PSI Inches Mercury Absolute Inches Mercury Gauge % Vacuum 760.0 760,000 14.7 29.92 0.00 0.00 750.0 750,000 15.5 29.5 0.42 1.3 735.6 735,600 14.2 28.9 1.02 1.9 700.0 700,000 13.5 27.6 2.32 7.9 600.0 600,000 11.6 23.6 6.32 21.0 500.0 500,000 9.7 19.7 10.22 34.0 400.0 400,000 7.7 15.7 14.22 47.0 380.0 380,000 7.3 15.0 14.92 50.0 300.0 300,000 5.8 11.8 18.12 61.0 200.0 200,000 3.9 7.85 22.07 74.0 100.0 100,000 1.93 3.94 25.98 87.0 90.0 90,000 1.74 3.54 26.38 88.0 80.0 80,000 1.55 3.15 26.77 89.5 70.0 70,000 1.35 2.76 27.16 90.8 60.0 60,000 1.16 2.36 27.56 92.1 51.7 51,700 1.00 2.03 27.89 93.0 50.0 50,000 0.97 1.97 27.95 93.5 40.0 40,000 0.77 1.57 28.35 94.8 30.0 30,000 0.58 1.18 28.74 96.1 25.4 25,400 0.14912 1.00 28.92 96.6 20.0 20,000 0.39 0.785 29.14 97.4 10.0 10,000 0.193 0.394 29.53 98.7 7.6 7,600 0.147 0.299 29.62 99.0 1.0 1,000 0.01934 0.03937 29.88 99.9 0.75 750 0.0145 0.0295 29.89 99.9 0.10 100 0.00193 0.00394 29.916 99.99 0.01 10 0.000193 0.000394 29.9196 99.999 0.00 0 0 0 29.92 100   Applications |  Products |  About Us |  Contact Us |  Request Information