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Term
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Description
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| Quality Assurance |
The activity of providing, to all concerned, the evidence needed to establish confidence that the qualify function is being performed adequately |
| Quality Control |
The regulatory process through which industry measures actual quality performance, compares it with standards and acts on the difference |
| Quality Function |
The entire collection of activities from which the industry achieves fitness for use, no matter where these activities are performed. |
| Radiation |
Heat transferred through space, generally by infrared or by visible light |
| Real Leak |
A real leak is a movement of atmospheric gases that results from a penetration through an opening (an actual hole) in a freeze dryer wall |
| Reconstitution |
Restoration of a dried substance to its former wet condition by the addition of the original solvent (generally pure water) |
| Recrystallization |
Most frequently the growth of larger crystals at the expense of smaller ones; i.e. a grain growth or ripening generally of ice, but a term to be examined and used with caution in any case |
| Relieve Valve |
Used for safety purposes to prevent damage in case excessive pressure is developed |
| Resistivity |
Specific electrical resistance. The resistance, in ohms, of a unit cube of a given material, measured between and across opposing faces |
| Resistivity Measurement |
(Resistance Measurement) Measurement of changes in the resistivity (or ohmic resistance) of a sample subjected to cooling and warming (i.e. during freezing and thawing), all with a view to the prediction (and possible control) of freeze drying behavior. Once generally measure actual ohmic resistance and derives resistivity by calculation |
| Retention |
A term signifying the persistence of structure in the dry cake as opposed to is loss (see Collapse) |
| Retrospective Validation |
Establishing documented evidence that a system does what it purports to do based on review and analysis of historic information |
| Revalidation |
Repetition of the validation or a specific portion of it |
| Rotary Vane Pump |
A mechanical pumping system with sliding vanes as the mechanical seal. Such a pump is typically two stage for freeze dryers |
| RTD |
(Resistant Temperature Detector) A transducer whose resistance change corresponds to temperature |
| Saturated Solution |
A solution in thermodynamic equilibrium with excess (crystalline) solute |
| Scroll Vacuum Pump |
(Dry Pump) A vacuum pump utilizing scroll compressor technology thereby not requiring a fluid such a vacuum pump oil in an effort to create vacuum. These pumps are typically more expensive that oil sealed rotary vane vacuum pumps but in some applications are required to ensure the highest level of cleanliness in a freeze dryer. |
| Secondary Drying |
That part of the freeze drying process that follows primary drying and is conventionally regarded as the second stage and a time for continuing solvent desorption |
| Sensible Heat |
Perceptible heat associated with temperature, since the heat content of a given mass of a substance in a given state varies with temperature |
| Septic |
An object or material that is free of organisms with may cause specific damage or infection |
| Shelf Life |
The length of time, depending on its stability, for which an object can be stored under given ambient conditions before its latent characteristic properties fall below a defined level |
| Shell Freezing |
A freezing process that forms a hollow frozen shell from liquid in a cylindrical or spherical container. The operation requires a slow rotation about a nearly horizontal axis and a partial or total immersion in a refrigerated fluid. May be done by hand or in a shell freezer |
| Shelves |
Freeze dryer shelves serve to support the product and (most frequently) to freeze and/or keep it frozen, then to furnish heat to facilitate the freeze drying process. A circulating fluid follows a serpentine path within each shelf, entering on one side and leaving on the other. Shelves may be movable for stoppering or fixed where stoppering is not required |
| Shrinkage |
Reduction in the size of the dry cake |
| Silicon Oil |
A often used fluid for circulating heat transfer in freeze dryers |
| Skin |
A relatively impermeable layer found on the upper surface of some freeze dried cakes formed, apparently, by the freeze drying of a locally concentrated solution and promoted by freezing from below |
| Soluble |
Able to dissolve, especially in water |
| Solute |
A substance capable of dissolving, especially in water |
| Sorption |
The physical or physico-chemical retention of one substance by another, generally of a smaller quantity of a "sorbate" by a larger quantity o a "sorbent" |
| Specific Heat |
The heat capacity of a substance compared with water in, most commonly, calories per gram or BTU per pound |
| State of Control |
A condition in which all operating variable that can affect performance remain within such ranges that the system or process performs consistently and as intended |
| Sterility Filter |
A bacteriological filter fitted closely over the opening of a product container in freeze drying |
| Sterilization |
The removal or destruction of all living organisms from an object or material |
| Sterilization Process |
A treatment process from which probability of any microorganism survival is less that 10 or one in a million |
| Sublimation |
The conversion of a material from a solid crystalline phase directly to a vapor phase, without passage through the liquid phase |
| Sub-Cooled Liquid |
The liquid refrigerant is cooled through an exchanger so that it increases the refrigeration effect as well as reduces the volume of gas flashed from the liquid refrigerant in passage through the expansion valve |
| Suction Line Accumulator |
A device that provides adequate refrigerant liquid slug protection (droplets of liquid refrigerant) from returning to the compression and causing damage to the compressor |
| Supercooling |
(Subcooling, Undercooling) The persistence of a liquid state below and equilibrium freezing point |
| Supersaturation |
The persistence of a solution at a concentration higher than that of the corresponding saturated solution |
| TDLAS |
Tunable Diode Laser Absorption Spectroscopy. Utilized to determine the temperature, pressure, velocity and mass flux of the gas under observation |
| Temperature |
The degree of hotness or coldness of a body |
| Thermal Treatment |
(Annealing, Tempering) The controlled and generally limited warming of frozen system with a view to further development of an ice phase and/or the crystallization of one or more other components capable of eutectic behavior |
| Thermocouple |
A temperature sensing device that is constructed of two dissimilar metals wherein a measurable, predictable voltage is generated corresponding to temperature |
| Thermocouple Vacuum Gauge |
An instrument for measuring total pressure in a vacuum system in which variations in the temperature of a heated filament are quantified by a thermocouple. Erroneously high pressure readings occur in the presence of water vapor. |
| Thermostatic Expansion Valve |
An automatic variable device controlling the flow of liquid refrigerant |
| Thief |
(Product Thief, Sample Thief) A device for removing vials from the freeze dryer through a vacuum lock, without interrupting the process, in order to carry out a check on residual moisture |
| Time Proportioning Control |
Action that varies the amount of 'on' and 'off' time when close to the set point, i.e., the proportional band. The variance is proportional to the difference between the set point and the actually process temperature. In other words, the amount of time the output relay is energized depends on the system temperature |
| Torr |
A unit of pressure measurement equivalent to 1 mm of mercury or 1000 microns of mercury |
| Triple Point |
A state in which three phases of the same substance (crystalline solid, liquid and vapor) coexist in thermodynamic equilibrium |
| Two State Compressor |
This is a specially built compressor. Its function is to be able to attain low temperatures by being able to operate at low pressures. It is two compressors built into one. A low stage connected internally and a high state connected externally with piping, called interstage |