Series 290 - User Manual
Contents
1. Figure 6 Series 290 Impactor Cut Points vs Flow Rate for Air at 25 C and 1 atm Marple Impactor Operator s Manual 17 1 From Figure 5 select the sampling flow rate based on the particle cut points desired and the vacuum capabilitv of the sampling pump See Figure 4 2 If the collection substrates are to be greased use the procedure in Section IV 7 Pre weigh all collection substrates and back up filters in a clean laboratory environment Record the weights A micro balance with a sensitivity of 0 001 or 0 01 mg is required The substrates and filter should be equilibrated with the lab environment for approximately 24 hours at a relative humidity of 50 or less before weighing and passed over a static eliminator if they have a static electricity charge 3 Assemble the cascade impactor as described in Section IV 5 4 Connect tubing to sampling pump and set the desired sampling flow rate on the pump Record the flow rate 5 Go into field attach cascade impactor to the lapel or pocket pump to the belt and the interconnecting tubing to both 6 Turn pump on Record sampling starting time and other required data on the data work sheet 7 After the desired sampling period turn pump off and record sampling termination time or elapsed time If desired the final flow rate can be checked to insure that constant flow was maintained throughout sampling The Model 715 two by two TM Portable Calibration Mass Flow Meter is ideal f2. Marple Impactor Operator s Manual 15 inlet part in the In Line Adapter The exit plastic hose fitting can be replaced with piping attached directly to the 1 8 NPT exit port in the impactor base The Series 290 can be operated in any orientation without significant internal losses due to particle sedimentation if the sampling flow rate is approximately 1 0 LPM or greater 7 Cleaning and Collection Substrates Since the cascade impactor is used for sampling particulate matter all internal surfaces of the stages should be free from dirt To clean disassemble the cascade impactor and wash each part in water with detergent or in alcohol Alternatively the parts can be cleaned in an ultrasonic bath Rinse and dry completely Hold stages up to a light to make sure all slots are free of foreign matter The slots also can be cleaned with shim stock When sampling solid particles the Model C 290 MY Mylar Collection Substrates are used with impaction grease to avoid possible particle bounce The Model C 290 SF Film Collection Substrates have a sticky surface on one side for collection of solid particles without bounce When sampling liquid aerosols bare C 290 MY Mylar substrates are recommended For sticky non bouncing solid aerosols the bare C 290 MY Mylar substrates can be effectively employed without encountering particle bounce but in this case the sampling flow rate should not exceed 2 LPM Application of Impaction Grease Although se
3. Mass Flow Meter Marple Impactor Operator s Manual 11 Total Pressure Drop butes of Water 0 3 Model 306 208 290 F Phnrp 10 Hs or Less Model 204 F is all Avtoss Filter 0 5 1 0 3 0 50 10 Flow Rate LPM Figure 4 Pressure Drop Across Series 290 with Clean 34 mm 5 micron PVC Back up Filter 30 Marple Impactor Operator s Manual 4 Carrying Case The Marple Impactor includes a carrying case for ease and portability 5 Specifications for Marple Personal Cascade Impactor Size and Weight Model No Over all Height of Impactor cm Width cm Depth cm Net Weight gm Shipping Weight kg Ib e Flow Rate e Construction Particle Size Cut Points e Collection Substrates e Back Up Filter e Outlet Fitting e Inlet Fitting Optional 2 liters per minute LPM nominal 0 5 to 5 LPM max range 1 to 3 LPM recommended Precision machined aluminum impactor stages nickel plated See Section VI 34mm diameter available in Film TM or Mylar 34 mm diameter PVC filter media 1 8 in NPT with 0 25 in 6 3 mm I D tube barb On Model 290 IA In Line Inlet Adapter 1 4 in NPT Marple Impactor Operator s Manual 13 6 Assembly The Marple Personal Cascade Impactors are assembled in the following Table II Assembly Listing for Marple Impactor 298 294 Inlet Visor 1 Inlet Visor 1 Inlet Visor 1 Inlet Cowl 2 Inlet Cowl 2 Inlet Cowl 2 impactor Stage 1 pact Stage tS Collect
4. have two features e It must have a constant flow controller which maintains the pre selected flow rate constant as the pressure drop through the back up filter increases with particulate loading e It must have a sufficient vacuum capability to maintain the pre selected flow rate over the entire sampling period The constant flow feature is essential 1 to avoid changing or smearing the impactor stage cut points which are flow rate dependent see Section VI to obtain accurate particle mass concentrations Figure 4 gives the pressure drop of the 294 296 and 298 versus flow rate with a clean Model F 290 P5 five micron PVC back up filter The pump selected should have a vacuum capability at least 1 5 to 2 times that shown in Figure 4 at the selected flow rate The Model 290 P Constant Flow Personal Sampling Pump has both required features at a flow rate of 2 LPM or less The Model 112 Constant Flow Air Sampler 0 10 LPM which is used for area sampling AC powered has the required features over the flow range 2 to 5 LPM for any sampling period The Model 112 has a constant flow vacuum capability in excess of 600 inches of water over 2 to 5 LPM For multi point measurements with a single pump Thermo Scientific provides 2 LPM critical orifices with a diaphragm vacuum pump Contact our Applications Engineers for more information The flow rate of the pump is accurately set with the convenient Model 715 two bv twol Calibration
5. of Stage 8 for the filter The corrected values of W are then used in the Impactor Data Work Sheet in Appendix A to calculate the corrected particle size distributions 26 Marple Impactor Operator s Manual Model 294 Model 208 Effectiveness Yo Calm Air Sampling Flow Rate 2 0 LEMI 0 3 1 0 3 0 10 30 Aerodynamic Particle Diameter micons Figure 10 Effectiveness for Models 294 and 298 Marple Impactor Operator s Manual 27 120 100 0 60 Sampling Eficiemov to Series 290 vith cowl ret 40 Cahn sir sampling Flow rate 2 0 LPM 20 1 0 3 0 10 30 Aerodynamic Particle Diameter micore Figure 11 Inlet Sampling Efficiency 28 Marple Impactor Operator s Manual Particle Loss Y Flow rate 2 0 LFM Aerocpramic Particle Diameter mimos Figure 12 Particle Loss in the Model 294 and 298 Impactors Marple Impactor Operator s Manual 29 SERVICE LOCATIONS For additional assistance Thermo Fisher Scientific has service available from exclusive distributors worldwide Contact one of the phone numbers below for product support and technical information or visit us on the web at www thermo com aqi 1 866 282 0430 Toll Free 1 508 520 0430 International
6. so that the slots in the stage are exposed 1 e the perforations in the substrates go over the impactor slot A tweezers is recommended to avoid hand contact Thus the 14 Marple Impactor Operator s Manual particles accelerating through a slotted jet in an impactor stage impact on the solid surface of the collection substrate laying over the top of the adjacent downstream stage After proper assembly of the stages collection substrates and filter attach the two thumb nuts to the two threaded studs and hand tighten until the stages bottom out on each other The cascade impactor unit is now sealed The large O ring Model 290 ORL in each stage provides the seal between the stages and the exterior The small O ring Model 290 ORS in the inner hub of each stage is used to hold down the collection substrate The small O rings may be removed if the substrates will not rotate during sampling as in stationary or area sampling To avoid possible sticking the small O rings need not be used with the Model C 290 SF Film TM Collection Substrates a Personal Sampling The alligator clip on the personal mounting bracket is clipped to the lapel or pocket flap Alternatively the clip can be rotated 1800 so that it points downward and clipped to the edge of the pocket For firmer mounting a piece of cardboard or equivalent rigid material can be cut to fit the inside of the pocket with the clip biting over both edge s of the pocket and th
7. the flow rate is too low internal sedimentation losses can increase Therefore the recommended flow range is 1 to 3 LPM for the Series 290 Marple Personal Cascade Impactors Aerodynamic equivalent particle diameter for spherical particles of unity mass density in air at 25 C and lacfm Barometric pressure and ambient temperature changes over 10 to 35 C have a negligible effect on the impactor cut points Although Table III and Figure 8 have accurate cut points for almost all applications for completeness we give the following theoretical relationship for the cut point of an impactor stage See Reference 1 D St w 9uL Cp Q Equation VI 1 Where St the square root of the Stoke s Number which depends on the jet throat length jet Reynold s number and jet to plate distance dimensionless If jet to plate distance 1 jet throat length 1 and jet Reynold s number 3000 then st 0 72 W slot width cm u gas viscosity gm cm sec L slot length cm Pp particle mass density gm cc Marple Impactor Operator s Manual 19 C Cunningham slip correction dimensionless Q volumetric flow rate in the impactor stage cc sec From Equation VI 1 we can see that D oc Or Figure 5 was generated from the experimental data at 2 LPM using this proportionality The gas viscosity u varies with gas composition and temperature The value uis 186 micropoise or 186 x 10 g cm sec for air at 25 C and 1 atm I
8. Series 290 Instruction Manual Marple Personal Cascade Impactors Part Number 100065 00 310ct2009 O 2007 Thermo Fisher Scientific Inc All rights reserved Specifications terms and pricing are subject to change Not all products are available in all countries Please consult your local sales representative for details Thermo Fisher Scientific Air Quality Instruments 27 Forge Parkway Franklin MA 02038 1 508 520 0430 www thermo com aqi Thermo Fisher Scientific WEEE Compliance This product is required to comply with the European Union s Waste Electrical amp Electronic Equipment WEEE Directive 2002 96 EC It is marked with the following symbol Thermo Fisher Scientific has contracted with one or more recycling disposal companies in each EU Member State and this product should be disposed of or recycled through them Further information on Thermo Fisher Scientific s compliance with these Directives the recyclers in your country and information on Thermo Fisher Scientific products which may assist the detection of substances subject to the RoHS Directive are available at www thermo com WEEERoHS WEEE Compliance Thermo Fisher Scientific Warranty Seller warrants that the Products will operate or perform substantially in conformance with Seller s published specifications and be free from defects in material and workmanship when subjected to normal proper and intended usage by properly trained personnel for the p
9. ampler worn by the worker To accomplish their objective Mr Michael A McCauley and his colleagues at NIOSH selected the team of Andersen Instrument Inc Instruments and Professor Virgil A Marple and Dr Kenneth Rubow of the University of Minnesota s Particle Technology Laboratory The result Series 290 Marple Personal Cascade Impactors The Series 290 impactors were designed in accordance with the proven Marple theory of impactors See Reference 1 The Model 294 four stage unit is specifically designed for wood dust sampling and has undergone extensive field testing See Reference 3 Thermo Fisher Scientific has since acquired Anderson Instrument Inc U S Patent No 3 983 743 Applications e Wood dust e Coal dust e Silica dust e Respirable dust sampling Inhalation toxicology aerobacteriology e Indoor air pollution e Low cost multi point sampling e Aerosol research II AERODYNAMIC PARTICLE SIZING The inlet visor and cowl prevent large wood chips cigarette ashes and other debris from entering the cascade impactor The design concept of the Marple Samplers evolved from the following information 4 Marple Impactor Operator s Manual The human respiratory tract is an aerodynamic classifying system for airborne particles A sampling device can be used as a substitute of the respiratory tract as a collector of airborne particles As such it should reproduce to a reasonable degree the human respiratory system so that lung penet
10. an be calculated including the inhalable thoracic and respirable fractions Figure 6 gives the methodology and formulas for calculating the two most popular types of particle size distributions Differential Particle Size Distribution Below is a plot on log log graph paper of AC Ajlog10Dpn vs GMD This plot is essentially a bar chart giving the particle mass concentration AC in each particle size band versus the geometric mean diameter GMD where GMD D D 1 This size distribution is the differential of the cumulative particle size distribution The 20 Marple Impactor Operator s Manual differential particle size distribution gives the details or fine structure of the particle size distribution Cumulative Particle Size Distribution This is a plot on log normal or log probability graph paper of N yA W Wiot VS Do isj 1 normal log The value W is the particle mass on impactor stage i and Wiot is the sum of the particle masses on all stages plus back up filter The total number of all stages is N The cumulative particle size distribution gives total particle mass smaller than particle size D as a function of D This type of particle size distribution gives us an over all picture of the size of the particles and is the integral of the differential particle size distribution On log normal paper the particle size distribution of many aerosols is a straight line or nearly so which can be complet
11. are not covered by the warranty provided in this warranty Buyer shall pay Seller therefor at Seller s then prevailing time and materials rates ANY INSTALLATION MAINTENANCE REPAIR SERVICE RELOCATION OR ALTERATION TO OR OF OR OTHER TAMPERING WITH THE PRODUCTS PERFORMED BY ANY PERSON OR ENTITY OTHER THAN SELLER WITHOUT SELLER S PRIOR WRITTEN APPROVAL OR ANY USE OF REPLACEMENT PARTS NOT SUPPLIED BY SELLER SHALL IMMEDIATELY VOID AND CANCEL ALL WARRANTIES WITH RESPECT TO THE AFFECTED PRODUCTS THE OBLIGATIONS CREATED BY THIS WARRANTY STATEMENT TO REPAIR OR REPLACE A DEFECTIVE PRODUCT SHALL BE THE SOLE REMEDY OF BUYER IN THE EVENT OF A DEFECTIVE PRODUCT EXCEPT AS EXPRESSLY PROVIDED IN THIS WARRANTY STATEMENT SELLER DISCLAIMS ALL OTHER WARRANTIES WHETHER EXPRESS OR IMPLIED ORAL OR WRITTEN WITH RESPECT TO THE PRODUCTS INCLUDING WITHOUT LIMITATION ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE SELLER DOES NOT WARRANT THAT THE PRODUCTS ARE ERROR FREE OR WILL ACCOMPLISH ANY PARTICULAR RESULT Thermo Fisher Scientific Table of Contents SECTION TITLE PAGE I Introduction 4 II Aerodvnamic Particle Sizing 4 III General Impactor Notes 7 IV Impactors 9 1 Description 9 2 Impactor Stages 9 3 Pump Selection 11 4 Carrying Case 13 5 Specification 13 6 Assembly 14 7 Cleaning amp Collection 16 Substrates V Sampling 16 VI Data Reduction and Presentation 17 VI Reference 23 Appendix A Example D
12. ata Reduction 24 Appendix B Correction Factor for Sampling 25 Efficiency and Internal Loss 2 Marple Impactor Operator s Manual List of Figures and Tables FIGURE TITLE 1 Sampler Simulation of Respiratory System 2 Jet Schematic of Marple Impactor Stage 3 Marple Personal Cascade Impactor 4 Pressure Drop Across Series 290 With Clean 34 mm 5 micron PVC Back up Filter 10 11 12 Marple Impactor Operator s Manual PAGE 10 12 I INTRODUCTION Thermo Scientific s unique Series 290 Marple Personal Cascade Impactor is the first precision cascade impactor worn by the worker giving complete accurate aerodynamic particle size distributions The personal mounting bracket is attached to the lapel or pocket The rugged Series 290 impactors combine compactness and light weight 7 oz max with Andersen Instrument Inc s patented radial slot design widely acclaimed for its accuracy minimal internal losses and absence of particle bounce Cascade impactors are available with 8 6 or 4 impactor stages all followed by a built in filter holder Impactor cut points range from 21 to 0 5 microns The Series 290 are operated at a flow rate of 2 LPM by the 290 P Constant Flow Personal Sampling Pump or similar pump attached to the belt and interconnected via tubing to the cascade impactor Development The US Natl Inst for Occupational Safety and Health NIOSH recognized the need to develop an accurate size fractionating wood dust s
13. e cardboard The hose is connected to the plastic elbow fitting on the impactor and the inlet to the personal sampling pump The elbow normally is turned downward The pump is clipped to the belt b Area Sampling The is an excellent cascade impactor for stationary ambient sampling in an occupational area inhalation toxicology chamber aerosol research facility or process stream In this case the personal mounting bracket is removed from the impactor base by unloosening the two thumb screws If no large debris is present in the aerosol the inlet visor and inlet cowl also can be removed The exit hose fitting is rotated so it points either sideways or upwards and the base of the cascade impactor is set on a horizontal surface For rigid stationary mounting it can be mounted to a suitable base using the two threaded holes in the impactor base The Model 290 P Constant Flo Personal Sampling Pump or equivalent Model 112 Constant Flow Air Sampler 0 10 LPM or other compatible vacuum supply is connected via tubing to the impactor c In Line Sampling The versatile Series 290 also can be used as an in line particle size fractionator for extracting a sample from inhalation toxicology chambers aerosol chambers process streams or stacks at temperatures not exceeding 1500F In this case the inlet visor and cowl are removed and replaced by the optional Model 290 IA In Line Adapter The sampled aerosol is connected to the 290 IA via the 1 4 NPT
14. e circular orifice and multiple rectangular orifice impactors by design must operate with higher orifice velocities This results in more turbulent flow greater re entrainment and a skewing of the size distribution toward the lower end i e the indicated size distribution being smaller than it really is III GENERAL IMPACTOR NOTES This instruction manual applies to the following Series 290 Marple Personal Cascade Impactors MODEL NO Cascade Impactors 298 Eight Stage Marple Personal Cascade Impactor 296 Six Stage Marple Personal Cascade Impactor 294 Four Stage Marple Personal Cascade Impactor Kits 298K Eight Stage Marple Personal Cascade Impactor Kit 296K Six Stage Marple Personal Cascade Impactor Kit 294K Four Stage Marple Personal Cascade Impactor Kit Marple Impactor Operator s Manual 7 Each Series 290 Cascade Impactor comes fully assembled with the following parts Table I Impactor Parts Inlet Visor Inlet Visor Inlet Visor Inlet Cowl Inlet Cowl Inlet Cowl 10 32 Thumb Nuts 2 10 32 Thumb Nuts 2 10 32 Thumb Nuts 2 Impactor Stages Impactor Stages Impactor Stages 1 2 3 4 5 6 7 8 3 4 5 6 7 8 1 2 3 5A Filter Hold Down Plate Filter Hold Down Plate Filter Hold Down Plate Filter Screen Filter Screen Filter Screen Base with hose fitting Base with hose fitting Base with hose fitting Mounting Bracket Mounting Bracket Mounting Bracket with clip with clip with clip 10 32 Thumb Screws 2 10 32 Thumb Screws 2 10 32 T
15. ectiveness of the Series 290 is higher than any other commercial impactor For particles smaller than 10 microns it is usually assumed that E 1 and no corrections are necessary For large particles the 290 experiences the lower effectiveness common in any particulate sampler and open faced filter Figure B 1 gives E e and f versus particle size for the model 294 and 298 at a flow rate of 2 LPM For other flow rates the 2 LPM data is used with acceptable accuracy although the effectiveness is probably higher at lower flow rates and lower at higher flow rates The corrected particle mass W for impactor stage 1 is found by dividing it by the effectiveness E Wicorrected W E B 2 Wi is found from column 5 of Figure 11 Impactor Data Work Sheet E is found from Figure 10 at the particle size D halfway between the cut point of stage i and stage i 1 or Dp Dpo Dpa 2 Table IV demonstrates this correction procedure by applying it to the example in Appendix A Marple Impactor Operator s Manual 25 Table IV Example correction for effectiveness Particulate Weight W Particle Size Dp Effectiveness Corrected Paticulate Stage mg From microns For E From Weigth W mg From Number Appendix A Exaluating E Figure 10 052 oo e osn o A 2 too 1 e owo or os os 1 00 l NOTES 1 By convention we use the cut point of Stage 1 2 By convention we use the cut point
16. ely described by two numerical parameters obtained from the straight line graph 1 The Mass Median Diameter MMD The MMD of the log normal distribution is the particle size Dp N where 2 W l Wiot 50 Thus 50 of the particle mass is borne by particles i j 1 larger than the MMD and 50 of the particle mass is borne by particles smaller than the MMD The MMD gives an overall measure of the size of the particles 2 The Geometric Standard Deviation 6 O is the ratio MMD D 1690 where D p 16 is the particle size for which 16 of the mass is borne by particles smaller than D 16 o is a measure of the spread in the particle size distribution if o 1 all of the particles are of the same size i e the aerosol is monodisperse 4 Example Calculation Appendix A gives an example data presentation calculation using the Figure 6 Impactor Data Work Sheet Differential and cumulative particle size distributions are plotted Marple Impactor Operator s Manual 21 VII REFERENCES 1 V A Marple B Y H Liu Characteristics of Laminar Jet Impactors Environmental Science and Technology 8 No 7 pp 648 654 July 1974 2 K L Rubow V A Marple and J G Olin A New Personal Cascade Impactor to be published 3 M A McCauley et al Field Studies with a new Personal Cascade Impactor to be published 22 Marple Impactor Operator s Manual APPENDIX A EXAMPLE DATA REDUCTION CALCULATION Perc
17. ent 0 1 1 10 Geometric Mean Diameter GMD microns 100 Figure 7 Differential Particle Size Distribution Marple Impactor Operator s Manual 23 24 Percent of Mass Less than Do 10 10 0 1 Equivalent Aerodynamic Diameter D microns Figure 9 Cumulative Particle Size Distribution on Log Normal Paper Marple Impactor Operator s Manual APPENDIX B CORRECTION FACTOR FOR SAMPLING EFFICIENCY AND INTERNAL LOSS The Series 290 Marple Personal Cascade Impactors are the most carefully and extensively characterized impactors available References 2 and 3 give complete data on impactor stage collection efficiencies sampling efficiency and internal losses Other commercial impactors seldom have published internal loss data in fact 1ts existence usually is ignored and never have published sampling efficiency data The purpose of this Appendix is to provide a correction factor effectiveness that corrects your data for sampling efficiency and internal losses At a given particle size two parameters determine effectiveness 1 The sampling efficiency e the percent of particles suspended in the ambient air that enter the inlet of the impactor 2 The internal loss f the percent of particles which enter the inlet and are collected on extraneous internal surfaces and not on the collection substrates or back up filter The effectiveness E of the cascade impactor is E e l f B 1 The eff
18. eriod of time set forth in the product documentation published specifications or package inserts Ifa period of time is not specified in Seller s product documentation published specifications or package inserts the warranty period shall be one 1 year from the date of shipment to Buyer for equipment and ninety 90 days for all other products the Warranty Period Seller agrees during the Warranty Period to repair or replace at Seller s option defective Products so as to cause the same to operate in substantial conformance with said published specifications provided that a Buyer shall promptly notify Seller in writing upon the discovery of any defect which notice shall include the product model and serial number if applicable and details of the warranty claim b after Seller s review Seller will provide Buyer with service data and or a Return Material Authorization RMA which may include biohazard decontamination procedures and other product specific handling instructions and c then if applicable Buyer may return the defective Products to Seller with all costs prepaid by Buyer Replacement parts may be new or refurbished at the election of Seller All replaced parts shall become the property of Seller Shipment to Buyer of repaired or replacement Products shall be made in accordance with the Delivery provisions of the Seller s Terms and Conditions of Sale Consumables including but not limited to lamps fuses batter
19. f desired the particle density p can be obtained from standard mass density measurements for the particulate sample For example p 2 54 for silica The cut offs in Table III and Figure 5 are for p 1 Normally correction is not made for non unity particle mass density in which case the cut offs become the equivalent aerodynamic particle diameter From Equation VI 1 we can see that D c pp Thus if we want to plot the actual particle size distribution p at for example a mass density of 3 0 we would divide the cutpoints D in Table III by 1 73 The Cunningham Correction C varies primarily with the particle size Dy For large particles greater than nominally 5 microns C is very close to unity Since C also depends on the mean free path of the gas it also depends on gas pressure temperature and composition 2 Particle Mass Concentration An important use of the Series 290 Marple Personal Impactor is calculation of the particle mass concentration C mg m in each impactor size range and the total mass concentration Cio mg m of all particles sampled Figure 6 is a useful Impactor Data Work Sheet for both recording and reducing the data It shows how to calculate C and Cio 3 Particle Size Distribution General A major use of Series 290 impactor data is determination of the complete particle size distribution of the sampled aerosol Given the complete particle size distribution the particle mass concentration in any size range c
20. humb Screws 2 For in line sampling the optional Model 290 IA In Line Inlet Adapter is provided The Series 290K Kits also include the Model 290 P Constant Flo Personal Sampling Pump and a length of interconnecting tubing For operation of the Model 290 P please consult the separate Model 290 P Instruction Manual provided with the Series 290K Kits Ordering More Collection Substrates and Filter Media The following special Series 290 impactor collection substrates and back up filter media are available Model C 290 MY Collection Substrates 34 mm dia Mylar media box of 100 Model C 290 SF Collection Substrates 34 mm dia Film TM media box of 100 Model F 290 P5 Filter Media 34 mm dia polyvinyl chloride media 5 micron pore size box of 100 8 Marple Impactor Operator s Manual Accessories Model 290 IGT Impaction Greasing Template Model 290G Impaction Grease Model 290 ORL Large O rings for Series 290 Viton pack of 10 Model 290 ORS Small O rings for Series 290 Viton pack of 10 IV IMPACTORS 1 Description The Marple Personal Cascade Impactor is a multi orifice multi stage cascade impactor used to measure the concentration and particle size distribution of all liquid and solid particulate matter The flow enters the inlet cowl and accelerates through the six radial slots in the first impactor stage Particles larger than the cut point of the first stage impact on the perforated collection substra
21. ies bulbs and other such expendable items are expressly excluded from the warranty under this warranty Notwithstanding the foregoing Products supplied by Seller that are obtained by Seller from an original manufacturer or third party supplier are not warranted by Seller but Seller agrees to assign to Buyer any warranty rights in such Product that Seller may have from the original manufacturer or third party supplier to the extent such assignment is allowed by such original manufacturer or third party supplier In no event shall Seller have any obligation to make repairs replacements or corrections required in whole or in part as the result of i normal wear and tear ii accident disaster or event of force majeure iii misuse fault or negligence of or by Buyer iv use of the Products in a manner for which they were not designed v causes external to the Products such as but not limited to power failure or electrical power surges vi improper storage and handling of the Products or vii use of the Products in combination with equipment or software not supplied by Seller If Seller determines that Products for which Buyer has requested warranty services are not Warranty Warranty covered by the warranty hereunder Buyer shall pay or reimburse Seller for all costs of investigating and responding to such request at Seller s then prevailing time and materials rates If Seller provides repair services or replacement parts that
22. ion Substrate Collection Substrate ImpactorStage2 M impacto Stage ZC Collection Substrate Colection Substrate Impactor Stage4 lmpactorStage4 J oooO Collection Substrate Collection Substrate Impactor Stage6 lmpactorStage6 oOo oOo Collection Substrate Colecton Substrate Impactor Stage 7 lmpactorStage7 o SoS S Collection Substrate Collection Substrate ImpactorStage8 Impactor Stge8 O o Oooo o Filter Hold Down Plate F Filter Hold Down Plate F Filter Hold Down Plate F Personal Mounting Bracket w Porco Mounting Bracket w Persona Mounting Bracket w Alligator Clip Alligator Clip Alligator Clip 10 32 Thumb Screws 10 32 Thumb Screws 10 32 Thumb Screws 1 4 1 D Tygon Tubing 1 4 1 D Tygon Tubing 1 4 1 D Tygon Tubing 290 P Constant Flo Sampling 290 P Constant Flo Sampling 290 P Constant Flo Sampling Pump or equivalent Pump or equivalent Pump or equivalent NOTES 1 Has Smiling Face 2 Has 1 in dia inlet hole Each impactor stage is numbered along its edge In assembly all numbers should line up along one of the two threaded studs in ascending order from inlet to exit No number should be upside down Note that in assembly the two threaded studs orient the impactor stages so that the slots in each stage are staggered from the slots in adjacent stages The impactor collection substrates are placed in the recess on the top surface of each impactor stage
23. or normal temperatures and pressures This factor corrects for the fact that as particle diameters approach the mean free path length of the gas molecules they tend to slip between gas molecules more easily and are therefore more easily able to cross the bulk flow stream lines The collection efficiency is therefore slightly greater than would be predicted by inertial impaction theory for particle diameters on the order of 1 or 2 microns The overlapping of particle size between stages which is naturally inherent in all cascade impaction devices is minimized in Thermo Scientific samplers by design Ranz and Wong 1952 stated that as a particle passes through a jet its nearness to the axis of the jet is one of the factors that determines whether or not the particle will reach the impaction surface In contrast to competitive samplers which have larger rectangular jets in each stage Thermo Scientific Samplers have small round jets Travel of the particle is thus confined near the axis of the jets The average distance of the particles from the axis of the jets is less than in other impactors Ranz and Wong 1952 also stated that round jets have sharper cutoffs than rectangular jets Thermo Scientific Samplers therefore on a theoretical basis should have a sharper cutoff Figure 2 shows how impaction occurs at the orifice collector interfaces Another inherent advantage of Thermo Scientific Marple Impactors over its competitors is that singl
24. or this application 8 For best results return to lab with fully assembled impactor transported in the up right position and sealed on the inlet to prevent sample contamination Alternatively the substrate can be removed in the field and placed in marked sealed containers for transporting to the lab In the lab disassemble stages and remove collection substrates maintaining their proper identification while doing so Weigh all collection substrates and back up filter as in Step 2 Record the final weights 9 Reduce the data as described in Section VI VI DATA REDUCTION AND PRESENTATION 1 Impactor Cut Points Use of cascade impactor data requires knowledge of the cut points of the impactor stages Table 8 1 gives the experimentally determined cut points at the design flow rate of 2 liters per minute LPM See Reference 2 18 Marple Impactor Operator s Manual Table III Series 290 Impactor Cut Points at 2 LPM Back Up Filter The internal losses in the Series 290 are minimal and usually are neglected in data reductions Reference 2 gives internal losses and detailed performance data Appendix B gives correction factors Although 2 LPM is the design flow rate for which most performance data is directly applicable the cut points for other flow rates in the 0 5 to 5 LPM range are calculated from equation VI 1 and are given in Figure 5 If the flow rate is too high particle bounce and internal impaction losses can increase If
25. ration by airborne particles can be predicted from sampling data The sampling instrument should therefore classify the particles collected according to the aerodynamic dimension that as Wells states is the true measure of lung penetration The fraction of inhaled particles retained in the respiratory system and the site of deposition vary with the size shape and density and all the physical properties of the particles that constitute the aerodynamic dimensions Figure 1 Thermo Scientific Samplers Simulate Human Respiratory System STAGE 1 7 Microns amp Above STAGE 2 4 7 7 Microns Pharynx Trachea amp STAGE 3 3 3 4 7 Microns Primary Bronchi i STAGE 4 2 1 3 3 Microns Secondary Bronchi VITA STAGE 5 1 1 2 1 Microns Terminal Bronchi Nf oo STAGE 6 0 65 1 1 Microns Alveoli if E Figure 1 Sampler Simulation of Respiratory System Methods that employ light scattering or filtration and microscopic sizing of particles do not reckon with density and some other properties that affect the movement of the particle in air and therefore do not give the desired information Because the lung Marple Impactor Operator s Manual 5 penetrability of unit density particles is known and since the particle sizes that are collected on each stage of the sampler have been determined then as long as a standard model of this samplers is used according to standard operating procedure the stage distribution of the collected material will indicate the e
26. te Then the air stream flows through the narrower slots in the second impactor stage smaller particles impact on the second collection substrate and so on The width of the radial slots are constant for each stage but are smaller for each succeeding stage Thus the jet velocity is higher for each succeeding stage and smaller particles eventually acquire sufficient momentum to impact on one of the collection substrates After the last impactor stage remaining fine particles are collected by the built in 34 mm filter 2 Impactors The Series 290 Marple Personal Cascade Impactor is constructed with aluminum stages that are held together by two screws with o ring gaskets Each impactor stage contains multiple precision drilled orifices When air is drawn through the sampler multiple jets of air in each stage direct any airborne particles toward the surface of the agar collection surface for that stage The size of the jet orifices is constant within each stage but are smaller in each succeeding stage The range of particle sizes collected on each stage depends on the jet velocity of the stage and cutoff of the previous stage Any particle not collected on the first stage follows the air stream around the edge to the next stage Marple Impactor Operator s Manual 9 4 Figure 3 Marple Personal Cascade Impactor 10 Marple Impactor Operator s Manual 3 Pump Selection The sampling pump for the Marple Personal Cascade Impactor must
27. veral low vapor pressure vacuum greases are suitable Model 290G Impaction Grease is a good choice The Model 290G is high vacuum grease The grease is applied as a suspension or solution of 10 to 20 percent grease in toluene The mixture is applied with a brush eyedropper or the Model 290IGS Impaction Grease Sprayer to the substrates The Model C 290 IGT Impaction Grease Template is recommended for proper application of the grease Place the substrate on the bottom plate of the template with the two locating pins through opposite perforations Place the top plate with six slots on top located by the two pins Apply the solution within the six slots in the template Note that the outer edge and center of the substrates must be devoid of grease or else the substrate will stick to the upstream impaction stage Allow the solvent to evaporate After drying a cloudy white film is visible The final greased substrate should be tacky but not slippery with a film thickness about equal to the diameter of the particles to be captured i e 1 to 10 microns thick V SAMPLING Although the following instructions directly apply to personal sampling they also are applicable to area or in line sampling An impactor data work sheet similar to that shown in Figure 6 is recommended for measurement quality assurance 16 Marple Impactor Operator s Manual 100 30 10 Cut Point Dj microne Lal 1 0 0 3 03 1 0 3 0 10 Flow Fate LPM
28. xtent to which the sample would have penetrated the respiratory system With this information and with knowledge of the chemical biological and or radiological properties of the material collected the exact nature and extent of the health hazard can be assessed AIR STREAM 4 yp 7 AIR STREAM A f g y y SN DA AE JET ETT efi A y o l l A poa UM ZA Trajectory of y impacted particle LZ Trajectory of partical too small to impact IMPACTION PLATE Figure 2 Jet Schematic of Marple Impactor Stage The earliest and most fundamental work in inertial impaction theory was conducted in the early 1950 s by Ranz and Wong In this work Ranz and Wong showed that the collection of a particle by an obstacle is a function of what is defined as the inertial impaction parameter K CpUD 18uD Where U is the relative velocity p is the particle density D is the particle diameter u is the gas viscosity D is the diameter of the round jet and C is the Cunningham slip correction factor Data from inertial impactors are normally presented as 50 effective cutoff diameters For the Thermo Scientific impactors containing round jets and flat collection surfaces the 50 effective cutoff diameter would yield a value of 0 14 for the inertial impaction parameter K 6 Marple Impactor Operator s Manual The Cunningham slip correction factor is equal to C 1 0 16x 10D f
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