CleanroomTestingandCertification_inhouseGHPtraining

Scan Filter• Use a square or rectangular probe – Equal to or greater than 10 mm in the axis of the scan• Scan 2.5 cm downstream of the filter face• Do not to exceed 5 cm/s• Identify leaks greater than 2 particles – 0.01% of 6 million = 600 counts per minute or 10 counts per second 151

Size Leaks• If leaks are detected under membrane: – Set the particle counter to “concentration mode” – Position probe under the defect to capture the maximum concentration of particles – Reset counter – Sample until the displayed concentration stabilizes – Record value and divide it by the aerosol challenge concentration – If the resulting value is greater than 0.010%, record the defect as a leak. 152

Example• Challenge using 480:1 dilutor = 14,000 – 14,000 x 480 = 6,720,000 particles / cu ft – 14,000 x 480 = 6,720,000 particles / 28.3 liters – or 273,450 particles per liter• Downstream of Leak = 26 particles / liter• Leak % = 26 / 273,450 X 100%• Leak = 0.011% 153

Integrated Scanning Device• Scan Air Pro by Lighthouse –Very user friendly –Reads leak size in % on probe• Greatly simplified filter scanning using a particle counter based instrument 154

Particle Counter Scan Test Method• Used by US semiconductor industry since mid- 1980’s• Method described in international standards– EN 1822 “HEPA / ULPA Filters”– IEST-RP-CC034 “HEPA and ULPA Filter Leak Tests”– ISO 14644-3 “Test Methods”– ISO 29463 “High-efficiency filters and filter media for removing particles from air”– NEBB “Procedural Standards for Certified Testing of Cleanrooms”• Already used by most filter manufacturers withauto-scan capability 155

Effort to Reduce PAO Exposure• Jim Meek of Baxter assigned project in 2009• Tested 12 defects in a glass media filter Challenge Concentration Instrument PAO 22 ug/l Photometer PAO 6 ug/l Photometer PAO 0.1 ug/l DPCMicrospheres 4.4 e7 / cu ft DPC• Found no significant difference in sizing leaks• Data suggests particle counter sizes leaks larger 156

Median Sized Leak Comparison 157

Publication• Alternative Methods for HEPA Filter Leak Detection –by Jim Meek, Dan Milholland, Laszlo • Published in March – April 2011 –Pharmaceutical Engineering 158

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Leak Testing – Fact or Myth?• Challenge aerosol must have 0.3 m particles to accurately detect filter defectsMyth 160

Challenge Aerosol Size• Particles of all sizes pass freely through filter defects• Example – A 500 um diameter media defect is 0.4% • A 0.5 mm mechanical pencil lead is 500 m – Assume a 0.3 m particle is the size of a tennis ball – A 500 m hole would be equivalent to football field 161

Leak Testing – Fact or Myth?• A defect is considered significant if it allows more than 0.01% of particles to pass unfiltered downstream of the HEPAMyth 162

No More Than 0.01% Unfiltered AirNo partial filtration by any defect• 100% of upstream particle concentration passes through a defect• Theoretically, the challenge concentration can be determined by sampling only the unfiltered air passing though defect (hole) 163

Sizing Leaks• Scanning probes sample 28.3 Lpm• All of the unfiltered air through the defect is captured by probe positioned over the leak – Filtered air from the surrounding intact media is also drawn into the probe, diluting the sample before entering the photometer• A 1% leak results when of 1% of the photometer sample volume comes from the defect and the remainder from the surrounding intact media 164

Filter Leak Illustration 165

Problem• What is the flow rate (cc per minute) of unfiltered air passing through a 0.010% leak? – Assume a photometer sample rate of 28.3 Lpm (28,300 cc per min) 166

Answer• 28.3 Lpm = 28,300 cc/m = 1.0 cfm• 28,300 cc/m x 0.0001 = 2.83 cc/m 167

Leak Testing – Fact or Myth?• All remote HEPA filter banks must be scan tested.Myth 168

Scan remote filter banks• Assume a HEPA filter bank is operating at 4.72 m3/sec• Assume 99.99% efficiency at 0.3 um – 100% - 99.99% = 0.01% penetration• 4.72 m3/sec x 0.0001 = 0.47 m3/sec or 28.3 l/m• Number of penetrating particles equals the number in 1 cfm of “unfiltered air” upstream• Why scan for 0.0001 cfm (0.01%) leaks? – Until we get 100% efficient HEPA filters, a total penetration test is adequate 169

Photometers and Aerosol Generators 170

Objectives• At end of session, you will be able to:• Differentiate between efficiency and leak testing of filters• Explain how aerosol generators work• Describe the difference types of aerosols• Describe components and functions of the photometer 171

Efficiency VS Leak Testing• Efficiency testing –Tests the filter with monodispersed aerosol –(Manufacturer’s test)• Leak testing –Tests the whole filtration system with polydispersed aerosol 172

Penetrometer• Determines the penetrationcharacteristics of filters• Thermal, monodispersed DOPaerosol of 0.3 m diameter forUSA markets–Most Penetrating Particle Size forrest of world• At rated flow rate 173

Filter Test Penetrometer• Hot Mono-dispersed 0.3 m DOP Aerosol – over 10 m long• Photometer used as the test instrument 174

Filter Test Penetrometer• Uses a particle counter and cold oil aerosolTDA-110P Cold Penetrometer 175

Aerosol Generators• Types of Aerosols• Aerosol Size• Types of Generators & Examples• Laskin Nozzle Type• Thermal Inert Gas Type• Generator Capacities & Concentration• DOP Alternatives• Generator Applications 176

Laskin Nozzle (Cold) Generator 177

Particle Size Distribution of Laskin Nozzle• Poly-dispersed Aerosol• Droplets range from < 0.1 - 3 micrometers• Count mean size  0.45 m• Mass mean size  0.7 m 178

Laskin Nozzle Output• Aerosol output of one Laskin nozzle using compressed air at 75 l/m @ 1.4 bar• Each nozzle produces – 382 mg DOP/min – 382 mg/min/system volumetric airflow, in m3/min = concentration in mg of DOP/m3 of air• Photometers requires > 10 g of oil/l of air – 10 g/l in 38.2 m3/min or 0.64 m3/second 179

Thermal (Hot) Aerosol Generator• Portable field unit producing poly- dispersed aerosol 180

Thermal Aerosol Generator• Poly-dispersed aerosol• Produces a higher concentration of aerosol than Laskin nozzle –For high flow systems up to 1400 m3/min• Particles size is smaller than Laskin nozzle 181

Summary• Efficiency vs. leak testing of filters –If you say efficiency, you must state particle size• Aerosol generators and operation• Different types of aerosols• Photometers requires a minimum of 10 mg/m3 aerosol challenge 182

Principles of Airflow 183

Objectives• At the end of the session, you will be able to: – Describe basic principles of airflow – Operate various airflow instruments• Explain the procedures and importance of instrument calibration• Make airflow measurements in ducts and at HEPA faces• Make important airflow and air pressure 184 calculations for cleanroom certification

Flow Direction• Air always flows from high pressure zone to low pressure zone.• The greater the pressure differential, the faster the air will flow. 185

Continuity Equation Q=VxA m3/s = m/s x m2Q Volumetric Flow Rate m3/sV Average Velocity m/sA Cross Sectional Area m2Where velocity measured 186

Question:What is the flow rate throughHEPA filter with a face velocityof 0.51 m/s and a face openingof 1.2 m by 0.61 m? 187

Answer: Q=VxA m3/s = m/s x m2Q = 0.51 m/s x (1.2 m x 0.61 m) Q = 0.37332 m3/sec 188

Pressure• Pressure = Force / Area• Unit of measure : mm of water column– Force exerted by a column of water over itscross-sectional area• You exert – 150 mm soda column whendrinking soda with a straw• 12 mm positive pressure against acleanroom wall can cause it tobuckle/move 189

mm of Water Column• A unit of pressure equal to the pressure exerted over a given surface area by a column of water at standard temperature Example: Pascal = 0.004 inches Water Column Pascal = 0.010 grams force / cm2 (grams force / cm2 = Newton / m2) 190

Relationship Between V & VP V = 1.29 (VP) ^ 0.5 (Pa)V Velocity m/sVP Velocity Pressure PaNote: For standard air density 191

Velocity Pressure VS Velocity 192

Static Pressure (SP) 193• Potential energy• Exerted in all directions• Positive SP may burst ducts• Negative SP may collapse ducts• Required to overcome resistance

Total Pressure (TP)• Pressure to start and maintain flow• TP = VP + SP (Kinetic + Potential)Total pressure = volumetric pressure + StaticPressure• Same sign notation as SP• Negative into fan• Positive out of fan 194

Losses 1951. Acceleration of air to duct velocity2. Hood entrance losses – Turbulence losses are a function of hood geometry3. Pressure drop through ductwork – Frictional losses – Losses less for smooth pipe – Losses proportional to length and inverse of diameter

Losses4. Pressure drop through fittings – Sudden change in direction or velocityWays to minimize losses: – Wide radius elbows – 30 or 45 degree branch entry – 45 degree tapered transition for duct size change 196

Airflow Measuring Devices1. Pitot-Static Tube –Primary instrument –Reads out VP –Clean air –Duct velocity at least 1500 FPM, (5.25 m/s) –Used for duct traverses 197

Pitot Tube 198

Other Instruments Use VP• Pitot tube typically used to measure relatively high air velocity in ducts or aircraft• Velgrid averages 16 TP (total pressure) and 16 SP (static pressure) points over 0.13 m2 of a filter face• Typically 150 mm from filter / screen• Commonly used in the USA for cleanroom air velocities 199

Measuring Airflow Uniformity 200