Glossary
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Aerosol Generator |
Instrument that can produce particulate matter having appropriate size range at a constant concentration, which maybe produced by thermal, pneumatic, hydraulic means. |
Aerosol Photometer |
Light-scattering airborne particle mass concentration measuring apparatus, which uses forward-scattering-light optical chamber to make measurements. |
Airborne Particle |
A solid or liquid object suspended in air, viable or non-viable. |
Airborne Particle Counter |
Is an instrument that counts and sizes the number of particles present within the air being sampled. Airborne particle counters are mainly used to test clean room to IS 14644-1 or EUGMP. |
Airflow |
The volume of air that flows through a particle counter, traditionally 1 cubic foot per minute (28.3 litres). More modern counters are in metric to meet the new standards and have typical flow rate of 50, 75 and 100 litres per minute. |
At Rest |
A completed clean room, complete with all equipment installed and operating but without people present. |
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Background Noise Count |
Count produced by a Particle Counter due to internal or external unwanted electronic signal when no particles exist. |
Bevaline Tubing |
Black tubing approved by the FDA for use with particle counters, lined with Teflon to reduce the build up of particles on the walls. Lengths of tubing are kept no longer than 3 meters because anything longer will produce particle dropout of larger particle sizes. |
Bio Contamination |
Contamination of materials, devices, individuals, surfaces, liquids, gasses or air with Viable Particles. |
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Calibration |
Confirmation of unit’s accuracy either Factory or in the field where sizing accuracy and flow are confirmed using Calibration standards and traceable Polystyrne Latex Spheres of know size. Up to now only the manufacturer’s method was available but a new standard ISO 21501 has been issued to provide a uniform calibration method across all brands. |
Cleandown Filter |
A filter that provides a portable source of clean air for zero count testing. It is used to prove that a counter is not counting false particles due to contamination. It is also used regularly to clean out any particle build up in a sensor. |
Cleanroom |
An environment where the air is filtered and controlled to provide clean conditions for the manufacture of sensitive products. |
Coincidence Loss |
The inability of a counter to properly count particles due to the overconcentration of particles, blocking each other in the sensor. |
Cold Smoke Generator |
An aerosol generator that uses a Laskin Nozzle to generate smoke aerosol using a pneumatic supply. Smoke output from generator is cold coming from the nozzle. |
Concentration Limit |
The maximum number of particles, at the primary channel, that a counter can distinguish before coincidence loss occurs. |
Concentration Mode |
The number of particles as per a pre-defined volume, cubic foot, cubic metre or litre. Results are updated and displayed every couple of seconds. |
Condensation Nucleus Counter (CNC) |
Gold standard method of calibrating particle counters under factory conditions by producing monosize samples of known particle numbers as a reference against which particle counters can be compared to. |
Contact Device |
Specially designed appliance holding an appropriate, sterile, culture medium with an accessible surface used for surface sampling. |
Count Median Particle Diameter (CMD) |
Median particle diameter based on the number of particles. Count Median is made up of one half of the particle number coming from particles smaller than the count median size and the other half coming from particles larger than the count median size. |
Cumulative Mode |
The number of particles at a channel size and larger. |
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Differential Mobility Analyser (DMA) |
Gold standard method of calibrating particle counters under factory conditions by producing monosize samples of known particle numbers as a reference against which particle counters can be compared to. |
Differential Mode |
Method of displaying a sample where by the number of particles counted between channels are displayed. |
Dioctyl Phthalate (DOP) |
Oil that use to be used in Aerosol Generators for Filter Integrity Testing within Cleanrooms/isolators. No longer used as being Carcinogenic. Can be used to describe the Filter Integrity Process “DOP Testing”. |
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EU GMP 2008 |
Latest version of EU methodology for aseptic processing including particle counting. |
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False Count |
Count produced by a Particle Counter due to internal or external unwanted electronic signal when no particles exist. |
False Count Rate |
The number of false counts per cubic metre in a sample of clean air at the first channel. |
Federal Standard 209 (FS 209) |
Older US suite of standards for Cleanroom classification. Cleanroom classification definitions from early versions of this standard are still used informally, such as Class 100, Class 10,000 or Class 100,000. |
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High Efficiency Particulate Air (HEPA) Filter |
Come in a number of Classes from H10-H14. Efficiency of filters is as follows:- H10 85%, H11 95%, H12 99.5%, H13 99.95% & H14 99.995% efficiency. |
High Pressure Diffuser |
A device used in series with a particle counter to enable sampling of high purity gases from high pressure gas lines. |
Hot Smoke Generator |
An aerosol generator that uses a Thermal Heating Block to generate smoke aerosol, using an inert gas (Nitrogen or CO₂) within the pneumatic supply. Smoke output from generator is hot coming from the nozzle. |
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Impact Sampler |
Device designed to sample particles in the air, or other gas, through a collision with a solid surface. |
Impingement Sampler |
Device designed to sample particles in the air, or other gas, through a collision with a liquid surface and the subsequent entering into the liquid. |
ISO 14644 |
Suite of International accepted standards for the classification of cleanrooms. |
ISO 21501-Part 4 |
New standard outlining the tests and procedures for calibrating particle counters. |
ISO Kenetic Probe |
Probe used for sampling particles in Laminar airflow cabinets and unidirectional airflow cleanrooms to reduce the effects of turbulence. |
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Latex Spheres |
NIST traceable polystyrene latex spheres used to approximate dust particle of known size for calibration purposes. |
Liquid Particle Counter |
Is an instrument that counts and sizes the number of particles that passes through them. The particle count results can be used to determine how clean the liquid being test is. Liquid particle counters can be used to check liquids to the following standards: UPS (United States Parmacopeia), ISO:4406;1999, NAS 1638 and SAE AS 4059. |
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Macro Particle |
A particle with diameter of greater than 5.0µm. |
Mass Median Particle Diameter (MMD) |
Median particle diameter based on the particle mass. Mass median is made up of one half of the particles coming from a size smaller than the mass median size and the other half coming from particles larger than the mass median size. |
Microns |
Unit of measure of particles. There are a million microns in a meter. Particles less than about 20 microns are invisible to the human eye. It is generally accepted that particles over 10 microns are too large (heavy) to float in air. |
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Ondina El |
Oil produced by Shell which can be used as a replacement to DOP. Normally used in the UK over PAO (Emery 3004). Other types of Ondina Oil include Shell Ondina 15 which is used in South Africa. |
Operational |
Where a clean room is functioning in its correct manner and also has the correct number of people present working. |
Optical Sensor |
Chamber in which light from a laser diode is scattered by particles and collected onto a detector. The larger the particle the more light that is scattered. This type of sensor uses the principle of light scattering detection first identified by the Carlow born Scientist John Tyndall in the 19th centaury. |
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Particle Concentration |
Number of individual particles per volume of air. |
Particle Counter |
Transducer which converts light to voltage in order to count and size particles of dust in clean environments. |
Particle Distribution |
The threshold used to size particles for a given size corresponds to the particle distribution for those particles. |
Particles |
Anything with mass, including dust, pollen, bacteria and water droplets. |
Poly-Alpha Olefin PAO (Emery 3004) |
Oil that is used as a replacement to DOP. Army Surgeon General’s Office (United States) gave its approval for use in lieu of DOP in January 1992. |
Pulse Height Analyser |
Instrument used to analyse the pulse signal from particle counters in terms of height. Displays particles as a normal distribution (Gaussian) around a median value. This median value is used to set the channel threshold. |
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Resolution |
The ability of a particle counter to distinguish between sizes. |
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SAE AS4059 |
Standard that defines cleanliness levels for particulate contamination of hydraulic fluids. The contamination levels selected are an extension of the widely accepted NAS 1638. |
Sensitivity |
The smallest particle a counter can detect. |
Settle Plate |
Suitable container (i.e. Petri Dish) of relevant size, containing an appropriate, sterile, culture medium, which is left open to the air for a defined period of time to collect viable particles depositing from the air. |
Signal to Noise Ratio |
The ratio between the first channel and background noise level. The better the ratio the less chance of a counter producing false counts. |
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Ultrafine Particle |
A particle with diameter of less than 0.1µm. |
Ultra Low Penetration Air (ULPA) Filter |
Come in a number of Classes from U15-U17. Efficiency of filters is as follows:- U15 99.9995%, U16 99.99995% & U17 99.999995% efficiency. |
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Viable Particle |
A Particle that consist of, or can support one or more live microorganisms. |
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