NEBB洁净室认证程序标准第一部分定义

2009年第3版
NEBB 美国国家环境平衡局   

    NEBB是世界著名的洁净室测试准则，它不同于ISO、IEST和209E，NEBB在洁净室测试及验证方面有着更为详细的内容，本文截取自NEBB2009年第3版，标准第一部分关于定义的内容，其中包括验收标准、精度、气溶胶、换气次数、校准、认证、分类、洁净室、洁净室安装、性能测试、清洁区、污染区、泄漏、压差、DOP等等内容，以下是该标准英文部分。

PART 1 - STANDARDS
SECTION 1 - DEFINITIONS

    These procedural standards have been developed using language defined by “Shall, Should,and May" as it relates to the standards and procedures described in this publication. It is important to note these particular words throughout this publication and how they pertain to NEBB standards and procedures.

Acceptance Criteria:

The value or range of values which is compared to the measured value that will determine if the results of the test pass or fail.

Accuracy:

The accuracy of an instrument is the capability of that instrument to indicate the true value of a measured quantity.

Aerosol (Cleanroom Use):

A suspension of solid (microspheres) or liquid particles (PAO, DOP,DEHS, etc.) in a gaseous medium used to evaluate HEPA filter integrity and/or efficiency.

Aerosol Challenge:

Challenging of a filter or an installed filter system by using a test aerosol.

Airborne particle:

Solid or liquid object, viable or non-viable, suspended in air.

Air Change Rate:

The calculated number of times the total air volume of a defined space is replaced in a given unit of time. This is ordinarily computed by dividing the total volume of the room supply or exhaust air in cubic meters (cubic feet), per unit of time, by the total volume of the subject space.

As-Built Facility:

A cleanroom which is complete and operating, with all services connected and functioning, but has no production equipment or operating personnel within the facility.

As-Found Data:

Data found and documented during initial testing prior to modifications of a system.

At-Rest Facility:

A cleanroom which is complete with all services functioning and with production equipment installed and capable of being operated or operating, as specified, but without operating personnel within the facility.

Calibration:

The act of comparing an instrument of unknown accuracy with a standard of known accuracy to detect, correlate, report, or eliminate by adjustment any variation in the accuracy of the tested instrument.

Certificate of Compliance (Conformance):

A written statement, signed by a qualified party, attestingthat the items or services are in accordance with specified requirements, and accompanied by additional information to substantiate the statement.

Certification:

The process of verifying compliance to meet the established acceptance criteria.

Classification:

A specified level of airborne particulate cleanliness applicable to a cleanroom or cleanzone, expressed in terms of a cleanliness class, in accordance with a referenced standard.

Cleanroom:

A specially constructed room in which the air supply, air distribution, filtration of air supply,materials of construction, and operating procedures are regulated to control airborne particle concentrations to meet appropriate cleanliness levels and other relevant parameters (e.g. temperature,humidity, pressure, etc.) as defined by ISO 14644, or any other regulatory entity.

Cleanroom Installation:

Cleanroom or one or more clean zones, together with all associated structures, air-treatment systems, services, and utilities.

Cleanroom Performance Testing (CPT):

The act of evaluating the performance of a cleanroom by performing a series of defined tests with prescribed procedures and reporting requirements.

Clean Zone:

A defined or dedicated space in which the concentration of airborne particles is controlled to specified limits or cleanliness levels and other relevant parameters (e.g. temperature, humidity,pressure,) as defined by ISO 14644, or any other regulatory entity.

Contamination:

The presence of any unwanted substance, material or energy which adversely affects a product or procedure in a cleanroom.

Controlled Environment:

A work space or room in which limited access or special environmental controls are designed into operational standards.

Counting Efficiency:

The ratio of the reported concentration of particles in a given size range to the actual concentration of such particles.

Designated Leak:

A leak from a HEPA/ULPA filter or filter bank that should be detectable during scanning of the filter installation with a discrete particle counter or aerosol photometer. When using a discrete particle counter, the designated leak is characterized by a designated number of counts,chosen to establish statistical probabilities related to its detection. When using a photometer a designated leak is normally characterized by a reading that is greater than 0.01% of the upstream challenge.

Differential Pressure (ΔP):

The difference between two pressures measured between a sample point and reference point.

Deficiency:

Any circumstance that adversely affects the specified performance of a device or system.

Dioctyl Phthalate (DOP):

A liquid plasticizer that can be used in an aerosolized form to challenge HEPA filters Dilution System: A device where a known volume of aerosol is mixed with clean air in a known volumetric ratio to reduce concentration.

Effective Filter Face Area:

The total area of active filter face through which air passes.

Filter Face Velocity:

Measuring the airflow velocity using an appropriate velocity measuring instrument at a specific distance from the filter face or by dividing the airflow volume by the effective filter face area.

Frequency:

As pertains to sound and vibration, the number of vibrations or waves or cycles of any periodic phenomenon per second. In noise control of cleanrooms, interest lies in the audible frequency range of 20 to 20,000 Hz (cycles per second).

HEPA Filter (High Efficiency Particulate Air Filter):

An extended media, dry-type filter in a rigid frame having a minimum particle-collection efficiency of 99.97 percent for 0.3 micron particulate at a rated airflow. HEPA filters may be specified by type and grade according to the current edition of IESTRP-CC001 HEPA and ULPA Filters. When the term HEPA filter is used in this publication, the term generally will apply to both HEPA and ULPA filters, unless the efficiency is stated and an ULPA filter specifically is required.

Isokinetic Sampling:

Any technique for collecting airborne particulate matter in which the collection is so designed that the air stream entering the probe is an airflow velocity that is near to, or equal to, that of the air passing into and around and outside the probe.

Laskin Nozzle:

A nozzle used for the generation of a heterogeneous DOP or PAO aerosol by compressed air.

Leak:

Penetration of contaminates that exceed an expected value of downstream concentrationthrough defects or lack of integrity.

May:

Used to indicate a course of action that is permissible as determined by the NEBB Certified CPT Firm.

Micrometer (Micron):

A unit of measurement equal to one-millionth of a meter or approximately 0.00003937 inch. (25 microns are approximately 0.001 inch).

Microspheres (Polystyrene Latex Spheres – PSL):

Manufactured highly uniform monodispersed particles in an aqueous solution. These particles are used to generate an aerosol challenge medium for testing cleanroom filters.

Mixed Airflow Cleanroom:

A hybrid cleanroom consisting of a combination of unidirectional airflow and non-unidirectional airflow within the same room.

NEBB Certified CPT Firm:

A NEBB Certified (CPT) Firm is a firm that has met and maintains all the requirements of the National Environmental Balancing Bureau (NEBB) for firm certification in Cleanroom Performance Testing and is currently certified by NEBB. A NEBB Certified CPT Firm shall employ at least one NEBB Certified CPT Professional in a full time management position.

NEBB Certified CPT Report:

The data presented in a NEBB Certified CPT Report accurately represents system measurements obtained in accordance with the current edition of the NEBB Procedural Standards for Certified Testing of Cleanrooms. Any variances from design, specified or agreed tolerances, are noted in the CPT report project summary.

NEBB Certified CPT Professional:

A NEBB Certified CPT Professional is a full time employee of the firm in a management position who has successfully passed the professional level written and practical qualification examinations and maintains the Certified CPT Professional re-certification requirements of NEBB.

NEBB Certified CPT Technician:

A NEBB Certified CPT Technician is a full time employee of the firm who has met the technician level experience requirements of NEBB and has successfully passed the technician level written and practical qualification examinations. A NEBB Certified CPT Technician shall be supervised by a NEBB Certified CPT Professional. (Supervision is not intended to infer constant oversight. A NEBB Certified CPT Technician is capable of performing assigned tasks with periodic supervision.)

Non-Unidirectional Airflow Cleanroom:

Air distribution where the supply air entering the clean zone mixes with the internal air by means of induction.

Occupancy State(s):

Three conditions of various stages of testing of a cleanroom: As-Built, At-Rest,and Operational.

Operational Facility:

A cleanroom which is complete with all services functioning, and with production equipment installed and operating under normal conditions with all operating personnel present.

Particle:

A solid or liquid object which, for purposes of classification of air cleanliness, falls within a cumulative distribution that is based upon a threshold (lower limit) size in the range from 0.1 to 5 microns (μm).

Particle Count:

Concentration expressed in terms of the number of particles per unit volume of air.Normally associated with the particles in the cleanroom or clean zone.

Particle Counter (Discrete):

A light scattering instrument with display or recording means to count and size discrete particles in air.

Particle Size:

An expression for the size of solid or liquid particles expressed as the apparent maximum linear dimension or diameter of the particle.

Particle Size Distribution:

Cumulative distribution of particle concentration as a function of particle size.

Poly-Alpha Olefin (PAO):

A synthetic, non-corrosive, non-mutagenic liquid compound which can be used to generate an aerosol to challenge HEPA filters.

Precision:

The ability of an instrument to produce repeatable readings of the same quantity under the same conditions. The precision of an instrument refers to its ability to produce a tightly grouped set of values around the mean value of the measured quantity.

Procedure:

The approach to and execution of a sequence of work operations to yield a repeatableand defined result.

Range:

The upper and lower limits of an instrument’s ability to measure the value of a quantity for which the instrument is calibrated.

Resolution:

The smallest change in a measured variable that an instrument can detect.

Room Velocity:

The average air velocity in the occupied zone at a specified distance downstream of the entrance zone.

Scanning:

A method for disclosing leaks in HEPA or ULPA filter units in which the probe inlet of anaerosol photometer or discrete particle counter is held approximately 25 mm (1 inch) from the filter face and moved in overlapping strokes across the test area at a rate based on the leak penetration to be detected and the upstream challenge concentration.

Shall:

The term is used to indicate mandatory requirements to be followed strictly in order to conform to the standards and procedures and from which no deviation is permitted. Note: In the event unique circumstances prevent a required action from being fulfilled, a notation shall be included in the CPT report explaining the exception. For example, such notation could be one of the following: Not Available, Not Applicable, or Not Accessible. The simple notation “N/A” without definition is not allowed.

Should:

The term is used to indicate that a certain course of action is preferred but not necessarilyrequired.

Standard:

A required qualification, action, or result for CPT work.

Testing, Adjusting, and Balancing (TAB):

TAB is a systematic process or service applied to heating, ventilating and air-conditioning (HVAC) systems and other environmental systems to achieve and document air and hydronic flow rates.

Testing Intervals:

6 Months:

      Testing that occurs at an average interval not exceeding 183 days throughout periods of operation use, subject to no interval exceeding 190 days.

12 Months:

      Testing that occurs at an average interval not exceeding 366 days throughout periods of operation use, subject to no interval exceeding 400 days.

24 Months:

      Testing that occurs at an average interval not exceeding 731 days throughout periods of operation use, subject to no interval exceeding 800 days.

Threshold Size:

A selected minimum particle size of particle counter measurement capability; the smallest particle size discrimination.

ULPA (Ultra-Low Penetration Air) filters:

An extended-medium dry-type filter in a rigid frame having a minimum particle collection efficiency of 99.999% for particles in the size range of 0.1 to 0.2 μm.

Ultra-fine particles:

A particle with an equivalent diameter less than 0.1micron (μm).

Unidirectional Airflow Cleanroom:

Controlled airflow through the entire cross-section of a clean zone with a uniform velocity and approximately parallel air stream that is no greater than 14 degrees from plumb.

Unidirectional Flow (Parallel Airflow):

Controlled airflow through the entire cross-section of a cleanzone with a steady velocity and approximately parallel streamlines. Fluid flow in which particles move in a smooth path substantially parallel to the paths followed by all other particles.

Uniform Airflow:

Airflow in which the relative standard deviation of velocities or volumes does not exceed 15 percent.

Upstream Particle Concentration:

Number of individual particles per unit volume of air associated with the number of particles upstream of the HEPA filter.

Validation:

Establishing documented evidence that a process or system, when operated within established parameters can perform effectively and reproducibly to produce a product meeting its predetermined specifications and quality attributes.

Work Station:

An open or enclosed work surface with direct HEPA filtered air supply.

Work Zone:

An area within the cleanroom which is designated for clean work and for which CPT is required. The work zone shall be identified by an entrance and exit plane normal to the airflow (where there is unidirectional airflow).

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