Vacuum Pump: Equipment Tab

Variable Definitions, Ranges and Default Values

The following table shows the meaning of the variables appearing in this tab, as well as their default values and their generally acceptable range. Note that due to the manner by which the variables are used by the sizing and costing equations, the range of acceptable values may be further reduced.

Variable	Default Value	Range

◙ Power The power of the vacuum pump.	0.0 kW	Positive
◙ Max Power The maximum power that a unit of this type is available for purchase in the market.	50.0 kW	Positive
◙ Suction Capacity The volumetric flowrate of evacuated gas at the vacuum pump’s inlet.	0.0 L/h	Positive

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Sizing: Design Mode

In Calculate (Design Mode), the user specifies the Maximum Power and the program calculates the Number of Units, Power and Suction Capacity. See also Pumping (by Vacuum Pump): Modeling Calculations.

Sizing: Rating Mode

In User-Defined (Rating Mode), the user specifies the Number of Units, (rated) Power and Suction Capacity. The program simply displays a warning if the required suction rate per unit exceeds the specified Suction Capacity or if the required power consumption per unit exceeds the specified (rated) Power.

Costing

The equipment purchase cost is based on the power consumed and the material of construction. The built-in model is based on a correlation by J. R. Cooper et al. (Chemical Process Equipment - Selection and Design, 2nd Ed., Elsevier, 2005). The correlation used is C = 9.93 X^1.03, where C is the FOB cost (in k$ in 1st quarter 2003) and X is the sizing factor in lb air/hr/Torr (0.3<X<15). Based on the ideal gas law, the sizing factor can be calculated as X = a * m/p = a * Q * M_air / R / T_air, where a=2.20462*101325/760, m is the air-equivalent mass flow rate in kg/hr, p is the suction pressure in Pa, Q is the suction capacity of evacuated gas in m3/h, M_air is the molar mass of air (28.96 g/mol), R is the universal gas constant (8.3144 m3-Pa/mol-K), and T_air is the air temperature (assumed equal to 20^oC). The material of construction is assumed to be SS316.

For more information on this equipment, see Vacuum Pump

For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.