Adsorptive Properties

  In 21CFR11 environments, this section is applicable only to members of the Developer group, however, members of the Analyst group may find information in this section helpful. Parameter file information that is available to Analysts is created by a member in the Developer group using information in this section.

(or click Edit next to the Adsorptive selection on the Analysis Conditions tab when in Advanced option presentation)

Adsorptive properties provide the adsorptive (analysis gas) characteristics for the analysis.

Adsorptive Properties
Field or Button Description
Adsorbate molecular weight [text box] The molecular mass is used for the weight % column of the isotherm tabular report and for the pressure composition isotherm plot.
Adsorptive [text box] Name of the adsorptive gas whose properties are being defined.
Density Conversion Factor [text box] Factor determined by obtaining the ratio of the gas density (STP) to the liquid volume. This field is disabled if Non-condensing Adsorptive is selected.

Dosing Method
[group box]

Normal. Dose from a pressurized tank of gas attached to a gas inlet port.

From last sample port. For krypton analysis only, the krypton is stored and dosed on the last port (2, 4, or 6 depending on system configuration).

  • Charge from inlet. Use to have the tube automatically charged with condensate from a gas inlet port after the dewar is raised.
  • Purify adsorptive. Use to have the condensate in the tube purified after charging by evacuating the gas over the condensate. If Charge from inlet is selected, select Purify adsorptive to have noncondensing contaminants automatically removed from the dosing tube prior to analysis. After the adsorptive has condensed in the Psat tube or sample port, the remaining gas in the tube will be evacuated to remove noncondensing contaminants. A small amount of the purified adsorptive condensate will then return to gas phase to restore equilibrium pressure in the tube.
Maximum manifold pressure [text box] The highest pressure to which the manifold will be dosed. To avoid damage to the analyzer, this number is limited to 925 mmHg. Low pressure sources will require lower numbers. For gases to be used for dosing after charging a tube from a gas inlet, enter the maximum pressure for dosing from the inlet, not from the tube of condensate.
Mnemonic [text box] Enter the mnemonic name for the adsorptive. If this gas is connected to a gas inlet port, this mnemonic must be entered in the Unit Configuration Gas Selection for the inlet port. See Unit Configuration
Molecular cross-sectional area [text box] The area that a single adsorbed molecule occupies on the surface of the sample. It is used in surface area calculations.
Non-condensing Adsorptive [check box] Select if using a non-condensing analysis gas. When selected, the Density conversion factor field and the PSAT vs T button are disabled.
Non-ideality factor [text box] Compensates for the forces of attraction between molecules in a real gas. This value is used for a calculated free space.
Psat vs T [button] Click to edit the Psat vs Temperature table. The table contains saturation pressures and their corresponding temperatures. To edit, click in a field and enter the value.
Therm. tran. hard-sphere diameter [text box]

An estimate of molecular size used in calculating the thermal transpiration correction.

  For fields and buttons not listed in this table, see Common Fields and Buttons.
 
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