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Term
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Description
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| Edge of Failure |
A control parameter value that, if exceeded, means adverse effect on state of control and/or fitness for use of the product |
| End Point |
(of Primary Drying) The instant when ice disappears completely from the product |
| End Point |
(of the freeze drying process) The point at which the product is sufficiently dry to render it acceptable |
| Equilibrium Melting Point |
The temperature at which the last ice crystal dissolves during the slow warming of a frozen aqueous system |
| Ethylene Oxide (ETO) |
A colorless, flammable, toxic gaseous or liquid compound, C2H40 |
| Eutectic Point |
The lowest temperature in any system at which a residual liquid phase persists in equilibrium with respective solid phases |
| Eutectic Temperature |
A point in a phase diagram where three of more phases are present and the temperature and composition of the liquid phase cannot be altered without the disappearance of one of the solid phases |
| Evaporation |
The transformation from a solid or liquid to vapor or gas involving the escape of molecules from a surface |
| Evaporative Cooling |
Cooling of a substance resulting from the loss of the more energetic molecules |
| Evaporative Freezing |
Freezing of a liquid as a result of evaporative cooling |
| Exothermic |
Accompanied by the evolution of heat |
| Expansion Tank |
A tank located in the shelf heat transfer system used as a holding and expansion tank for the transfer fluid |
| F Value |
A physical parameter for the reference temperature used to predict the biological outcome of a process based on a straight-line, semi logarithmic microbial destruction model. When the reference temperature is 121.1C provided via moist heat (saturated steam), the F value is referred to as Fo |
| Filter or Filter/Drier |
There are two system that have their contents filtered or filter/dried. They are the shelf circulation fluid and the refrigeration system. |
| Free Water |
Free water is that water that is more or less readily removed from the product in the context of a given drying operation. Typically biological or chemical changes are minimized or stopped when free water is removed |
| Freeze Drying |
(Lyophilization) Any process that involves the conversion of water to ice, the sublimation of the ice and further removal of some or all of any water not converted to ice, with the intent of rendering the product biologically and chemically inactive until reconstituted at some future date. |
| Freeze Drying Cycle |
A sequence of more or less well defined steps that describes a succession of operations required during the freeze drying of a product. Freeze drying cycles most commonly state required shelf temperatures and system pressure and rates at which either or both should be changed |
| Freeze Drying Front |
(Sublimation Interface) A term applied, where appropriate, to describe an evidently continues boundary between the frozen product and the cake freed from ice by sublimation |
| Freeze Drying Temperature |
An expression that may refer to a temperature in a product or to the temperature of the shelf on which a product is being freeze dried. |
| Freezing |
Solidification, the process of changing from a liquid to a solid form, particularly from water to ice with the removal of heat. Freezing may involve a controlled change of the product temperature as a function of time to assure a completion of the process |
| Freezing Point |
The temperature at which liquid and solid crystalline forms of the same material are in equilibrium at standard atmospheric pressure. |
| Frozen |
Reduced to a solid state |
| Gas |
A state of matter in which atoms and/or modules have free translational movement so that a gaseous substance completely fills a container irrespective of size |
| Gas Ballast |
Used in a vacuum system on the vacuum pump to remove small amounts of moisture in the vacuum pump oil |
| Gas Ballasting |
The admission of air to the interior of a rotary vacuum pump to reduce condensation of vapor in the oil |
| Gas Bleed |
To control the pressure in the chamber during the freeze drying cycle to help the drying process, typically to improve heat transfer to the product |
| Glass |
Any physically solid amorphous, non crystalline, material. Aqueous glasses may be formed during freezing and persist, with reduced water content, during and after freeze drying |
| Glass Transition Temperature |
(Tg') The temperature at which an amorphous substance having viscoelastic properties is transformed into one with elastic solid properties or vice versa |
| GMP |
Good Manufacturing Practices. The Federal Drug Administration's guidelines for the pharmaceutical industry |
| Heat |
Transmissible energy, either as radiation or as thermal (i.e. Kinetic) energy resident in a gas, liquid or solid |
| Heat Exchanger |
A mechanical devise located in circulation and refrigeration systems that transfers heat from the circulation system to the refrigeration system. May "plate" type heat exchanger most commonly in freeze dryers |
| Heat Transfer |
The transfer of heat from a higher to a lower temperature, in a solid by conduction, in a fluid by conduction and convection, and through space by radiation. Heat may also be consumed by evaporation (or sublimation) and generated by condensation, as in a freeze drying process |
| Heat Transfer Fluid |
A liquid of suitable properties for transferring heat to and from a component, for example, a shelf or condenser in a freeze dryer. |
| Heterogeneous |
Having a large number of structural variations |
| Homogenous |
Having a single structural appearance with no variation |
| Hot Gas Defrost |
A function and use of a refrigeration system, employed, when desired, to defrost the condenser after a lyophilization cycle is complete |
| Hydrophilic |
Having an affinity for water |
| Hydrophobic |
Having a tendency to not wet, be wetted or to dissolve in water. |
| Hysteresis |
A difference in the response of a physical system to a change in constraint according to the polarity of the change |