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New Regulations Concerning Airborne Particle Counters (ISO 21501 and ISO 14644) Bob Latimer, Tony Harrison 2008 Cleanrooms Worldwide eVent.

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Presentation on theme: "New Regulations Concerning Airborne Particle Counters (ISO 21501 and ISO 14644) Bob Latimer, Tony Harrison 2008 Cleanrooms Worldwide eVent."— Presentation transcript:

1 New Regulations Concerning Airborne Particle Counters (ISO and ISO 14644) Bob Latimer, Tony Harrison 2008 Cleanrooms Worldwide eVent

2 Copyright 2008 Hach Ultra Analytics – Page 2 Agenda 1.cGMP and EU GMP Guidelines 2.ISO Key Elements 3.What is ISO Replacing 4.Air Particle Sensors and Calibration – The Basics 5.Counting Efficiency 6.Resolution 7.Signal to Noise Ratio and False Count Rate 8.Summary

3 Copyright 2008 Hach Ultra Analytics – Page 3 Aseptic Pharmaceutical Manufacturing The cGMP and EU GMP guidelines specify particle count limits based upon cleanroom classifications such as Grade A, B, etc. Both EU GMP and cGMP reference ISO for determining cleanroom classification. The next revision of ISO will refer to ISO , a calibration standard for air particle counters, ratified February ISO already cross references back to ISO ISO states – Instruments that conform to this part of ISO are used for the classification of air cleanliness in cleanrooms and associated controlled environments in accordance with ISO

4 Copyright 2008 Hach Ultra Analytics – Page 4 Calibration to ISO Key Elements Particle size calibration using PSL particles traceable to an international standard and within a standard uncertainty < =2.5% The use of a Pulse Height Analyzer (PHA) to determine sensor response for each of the particle counters size channels The intent is to improve the accuracy of particle count data and improve instrument to instrument correlation

5 Copyright 2008 Hach Ultra Analytics – Page 5 ISO – Sub Documents ISO describes the instruments and calibration requirements. Part 2: Light scattering liquid-borne particle counter Part 3: Light extinction liquid-borne particle counter Part 4: Light scattering airborne particle counter for clean spaces

6 Copyright 2008 Hach Ultra Analytics – Page 6 What Standards/Guidelines Existed Prior to ISO 21501? JIS B 9921:1997 A Japanese standard which comprehensively deals with OPC design performance, most notably in the area of counting efficiency. ASTM F (updated 2003) Standard Practice for Calibration of an Airborne Particle Counter Using Mono-disperse Spherical Particles (Officially withdrawn 2007). IEST-RP-CC014.1 Calibration and Characterization of Optical Airborne Particle Counters (Provides actual methods to perform the calibration). ISO

7 Copyright 2008 Hach Ultra Analytics – Page 7 ISO Compared to Existing Re-calibration A key difference with ISO is that key calibration attributes are incorporated within the scope of instrument re-calibration. Minimum content on ISO calibration certificate.

8 Copyright 2008 Hach Ultra Analytics – Page 8 MET ONE Air Particle Counters and ISO Calibration MET ONE Air Particle Counter 0.5µm and 5.0µm

9 Copyright 2008 Hach Ultra Analytics – Page 9 Optical Particle Sensor Configuration Light Trap Collection Optics Reflector Detection Zone

10 Copyright 2008 Hach Ultra Analytics – Page 10 Laser Diode Detector Collection Optics Particle Light Trap Detecting Particles t v Oscilloscope Pulse Height Analyser

11 Copyright 2008 Hach Ultra Analytics – Page 11 The Pulse Height Analyzer (PHA) When a particle sensors output is connected to an oscilloscopes input the particles appear as a series of voltage pulses in time. The amplitudes of the pulses relate to the amount of light energy scattered by the particle and are therefore related to the sizes of the particles. When the sensors signal output is connected to Pulse Height Analyzer (PHA) the particles appear as a distribution with the x- axis being pulse height and the y axis being number of particles. The above picture depicts a typical room air sample. The above picture depicts a PHA response to a mono-dispersed challenge such as PSL calibration spheres.

12 Copyright 2008 Hach Ultra Analytics – Page 12 Calibrating Air Particle Counters: NIST-traceable Particles Mean size 498 nm +/- 5 nm Std Deviation 7.9 nm Size (nm) NIST-traceable standard particles have normal size distribution. Nominal size and CV are certified C.V. (RSD) = Std Dev Mean size x 100

13 Copyright 2008 Hach Ultra Analytics – Page 13 Selecting the Correct Calibration Voltage The calibration voltage for a given PSL introduction mode median ISO requires that the PHA response to the PSL spheres is interpreted as the median. This is the point where an equal number of particles fall on each side of the bisected distribution. For normal distributions the mode and the median fall at the same point. This is not always the case in particle counting where skewed or irregular distributions are not uncommon.

14 Copyright 2008 Hach Ultra Analytics – Page 14 Calibrating Air Particle Counters: Constructing the Calibration Voltage Calibration requires that a variety of different PSL sizes are run and the median voltages are recorded Calibration Example

15 Calibration of Air Particle Counters

16 Copyright 2008 Hach Ultra Analytics – Page 16 ISO 21501: Counting Efficiency = x 100 (%) CCoCCo Counting efficiency has arguably been the biggest variable impacting the accuracy of airborne counters. Counting efficiency refers to the ability of the instrument to count particles at a specified size. ISO makes use of the specification for counting efficiency that was defined in the JIS B 9921 standard. The particle concentration (C) displayed by particle counter Concentration (Co) of particles drawn into the inlet of an OPC C.E. is the ratio:

17 Copyright 2008 Hach Ultra Analytics – Page 17 Channel 1 size (um) Noise N Counting Efficiency – ISO Comparison to 100% Count Standard Channel 1 set to 100% efficiency for UUT channel 1 size Noise N Unit Under test NIST-traceable 100% Count standard Example: Channel 1. Set to recover 100% of the challenge PLS ISO Limits 50% +/- 20% (30% to 70%) UUT Standard NIST Traceable PSL Challenge

18 Copyright 2008 Hach Ultra Analytics – Page 18 The counting efficiency for PSL particles of the UUT minimum measurable particle size shall be within the range 30% to 70% ISO Limits 50% +/- 20% (30% to 70%) Channel 1 size (um) OPC smallest specified size. Noise N ISO and Counting Efficiency: A Two Part Test At 1.5 x to 2 x the particle counters minimum specified size all particles should be counted in the first channel. ISO allowed limits are 90% to 110% Channel 1 size (um)Noise N AND for PLS particles of 1.5 times or over up to and including two times the minimum measurable particle size value, shall be 90% to 110%

19 Copyright 2008 Hach Ultra Analytics – Page 19 ISO 21501: Resolution N Particle size 0.3µm Resolution – The ability to differentiate between similarly sized particles Affected by instrument quality and alignment of the sensor optics 0.5µm

20 Copyright 2008 Hach Ultra Analytics – Page 20 Resolution – Why It Is Important N Particle size 0.3µm A particle sensor with poor resolution, such as the one above, cannot reliably distinguish between different sized particles. 0.5µm

21 Copyright 2008 Hach Ultra Analytics – Page D1D1 D2D2 D Peak (median) 61% of peak ISO requires that resolution be calculated from +/- 1 standard deviation from the median. The higher of the two values for (SD) is selected. Resolution R% = CV(%) = RSD(%) R% = x 100 (%) 2 - P 2 X P where R Resolution Observed SD in µm P PSL SD in m X P PSL Size in µm

22 Copyright 2008 Hach Ultra Analytics – Page 22 ISO 21501: False Count Rate – Affected by Signal to Noise Ratio Channel 1 Peak to Valley Ratio Noise Channel 1 Note: ISO does not specify a minimum S:N ratio although False Count Rate is (next slide). Peak to Valley is described although not specified. Hach Ultra maintains an internal Peak to Valley specification of 2:1 Signal

23 ISO False Count Rate

24 Copyright 2008 Hach Ultra Analytics – Page 24 ISO Summary ISO ParametersLimit Sampling flow rate (volumetric)± 5% Counting efficiency at channel 1 50% ± 20% Counting efficiency at particle size 1.5 to 2 times channel 1 100% ± 10% Particle size setting error 10% Instrument resolution (at manufacturers specified size) 15% Zero count test 1 count / 5 minutes Maximum particle number concentration (manufacturer specified) 10% Sampling time± 1% Response rate 0.5% Calibration interval 1 year Test Report Must Include as a Minimum: Date of calibration Particle sizes used for calibration Flow rate Size resolution Counting efficiency False count rate

25 Copyright 2008 Hach Ultra Analytics – Page 25 Hach Ultra and ISO Hach Ultra has completed a full migration to ISO calibrations. Hach Ultra offers a complete line of ISO compliant air particle counters. Hach Ultra offers full ISO field and factory calibration offerings designed to ensure accurate and efficient service that goes beyond the instrument –Certified Calibration Service Agreements with your choice of either In-House and\or Service-at-your-Site options. –Prescheduled calibration and preventative maintenance services

26 Copyright 2008 Hach Ultra Analytics – Page 26 Hach Ultra and ISO Calibrations performed by Hach Ultra ISO certified technicians 60 Global Direct Certified field technicians guarantees prompt qualified support –Hach Ultra technicians average over 8 years of Hach Ultra calibration experience per associate 10 ISO capable factory service centers –1 US based ISO 9001:2000 certified factory service center –3 Strategically located US remote depot service centers to support walk-in and close to customer depot support –5 European remote factory service centers –1 Asian remote factory service center

27 Copyright 2008 Hach Ultra Analytics – Page 27 Hach Ultra and ISO Customer support available at

28 Copyright 2008 Hach Ultra Analytics – Page 28 Thank You


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