Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Air Cleanliness Class: Federal or ISO standard which rates the maximum allowable concentration of airborne particles in a given cleanroom. For example, a Class 100 cleanroom is measured to have no more than 100 particles of 0.5 microns in size per cubic foot, a Class 10, to have no more than 10.

Air Shower: An enclosed chamber using numerous air nozzles to remove contaminants from an individual’s cleanroom garment, prior to cleanroom entry.

As-Built: One of three operational states used in defining cleanroom airborne particle concentrations. Describes a cleanroom complete and ready for use, but containing no equipment or personnel.

At-Rest: One of three operational states used in defining cleanroom airborne particle concentrations. Describes a cleanroom complete and ready for use, with all services functioning, but without equipment or personnel.

Bunny Suit: Common industry term for a full body protective cleanroom garment.

Class Level: SEE Air Cleanliness Class

cleanroom: A room in which the concentration of airborne particles is controlled to a specific limit.

Clean Work Area (CWA): An area in which good housekeeping procedures, personnel controls, and contamination restraints are utilized to maintain a high level of cleanliness.

Contamination: An unwanted material or substance that causes cleanliness degradation in the cleanroom.

Contamination Control: Organized action to control the level of contamination.

Federal Standard 209: Defines standard particle size distributions and classes of air cleanliness. The current version is 209E.

Fiber: A particle whose length-to-width ratio exceeds 10:1, with a minimum length of 100 microns.

Generally Clean: KSC surface cleanliness level denoting freedom from manufacturing residue such as dirt, oil, grease, etc. Abbreviated GC.

HEPA Filter: High Efficiency Particle Air Filter having a minimal particle removal efficiency of 99.97% for all particles at the 0.3 micron diameter level.

ISO 14644-1: Defines International Standard Organization’s standard particle size distribution and classes of air cleanliness, approximately equal to Federal Standard 209E.

KSC-C-123H: Kennedy Space Center (NASA) surface cleanliness specifications document.

Laminar Air Flow: Air circulation in a cleanroom having uniform velocity and direction, minimizing contaminant re-distribution caused by turbulent air/vortex effects.

Micron: Unit of measure defined as a millionth of a meter, a thousandth of a millimeter or 39.4 millionths of an inch.

MIL-STD-1246: The military standard for product cleanliness levels and contamination control program.

Non-Volatile Residue (NVR): The soluble material (or suspended) material and insoluble particulate matter remaining after the evaporation of a liquid.

Operational: One of three operational states used in defining cleanroom airborne particle concentrations. Describes a cleanroom in normal operation complete with equipment and personnel performing their normal work functions.

Operational State: An aspect of Federal and ISO standards defining cleanroom airborne particle concentrations. Whenever cleanroom Class Levels are specified, one of three operational states must also be specified (“At-rest”, “As-built”, or “Operational”).

Particle: A small quantity of a solid or liquid material with definable shape or mass, with a length-to-width ratio of less than 10:1.

Particle Contamination: Unwanted presence of a substance, usually individually definable in terms of shape, length, width, and depth (e.g. dust particles on a mirror).

Particle Size: Expressed as the apparent maximum linear displacement or diameter of a particle.

Pass-Over Bench: Physical design feature of a garment changing area used to segregate one cleanliness zone from another (cleaner) zone, as the various stages of garment donning are carried out.

Pass-Through: Tightly sealed portal, typically employing interlocking doors and other contamination safeguards, located in the walls of a cleanroom to allow the passage of materials and objects into a clean environment.

Positive Air Pressure: Maintenance of cleanroom atmospheres at a higher internal pressure in relation to exterior areas. The higher interior pressure air ensures seal failures or leaks create a draft of air flowing out of the cleanroom, preventing contaminant entry.

Precision Cleaning: KSC surface cleanliness level denoting product cleanliness is required greater than the level often detected by visual means and requiring cleanliness verification by particle analysis and non-volatile analysis as specified.

Surface Cleanliness Level: An established level of maximum allowable particles and/or NVR contamination ranging from visibly clean to precision cleaning levels.

Turbulent Air: Air flow which varies erratically in velocity, magnitude and/or direction.

ULPA Filter: UltraHigh Efficiency Particle Air Filter having a minimal particle removal efficiency of 99.999% for all particles as small as 0.12 microns.

Visibly Clean: KSC surface cleanliness level denoting the absence of all particulate and non-particulate matter visible to the normal unaided eye or the corrected-vision eye. Abbreviated VC.

Visibly Clean – inspected with Ultra-Violet light: KSC surface cleanliness level denoting the absence of all particulate and non-particulate matter visible to the normal unaided eye or the corrected-vision eye when examined under an ultra-violet light. Abbreviated UV.

Vortex Effect: A cleanroom air flow pattern with a whirling or circular motion that tends to form a vacuum in the center, drawing in contaminants and dispersing them throughout the work area.

Witness Plate: Passive sampling surface exposed to a cleanroom environment and periodically analyzed to determine the type and amounts of contamination in a particular location.