Presentation on theme: "AIR TESTING FOR CONTAMINANTS IN MINES"— Presentation transcript:
1 AIR TESTING FOR CONTAMINANTS IN MINES Good afternoon friends and colleagues. I am happy to be here in this beautiful city to talk to you about air testing for contaminants in mines.I’ve been working in the area of air sampling for more than 24 years, but I must admit I’ve never actually been in a mine.But I have gone scuba diving in a quarry so that should count for something AND my grandfather spent his working life in a W. PA coal mine or as I like to say STEELERS COUNTRY.
2 TYPICAL AIR CONTAMINANTS IN MINING OPERATIONS PARTICULATESMetal fumes from welding operationsRespirable dust including crystalline silica in silica-containing rock and coal dustAsbestos in asbestos-containing oreDiesel particulate from engine exhaustLike most industrial operations, the air contaminants in mining operations include particulates as well as gases/vapors.Typical particulate contaminants include metals, respirable dustd such as respirable coal dust and crystalline silica, asbestos, and diesel particulate.
3 TYPICAL AIR CONTAMINANTS IN MINING OPERATIONS GASES AND VAPORSNaturally occurring methane and hydrogen sulfideNitrogen oxides and carbon monoxide from engine exhaust and blasting operationsFormaldehyde from urea-formaldehyde or isocyanates from polyurethane foamsOrganic solvents used in cleaning or other applicationsTypical air contaminants in the gas/vapor phase include:-Methane and H2S that are naturally occurring-Nitrogen oxides and CO from gaseous emissions-Formaldehyde or isocyanates from foams used to plug up ventilation systems-Organic solvents used for cleaning
4 AIR CONTAMINANTS IN URANIUM MINING OPERATIONS Radon-Naturally occurring radioactive gasRadon Daughters-Fine solid particles which result from the radioactive decay of radon gas; attach themselves to airborne dust and smokes and reach the gas exchange section of the lungs where alpha radiation is emitted.Uranium mines also have some unique air contaminants:In the gaseous phase-radonIn the particulate phase-radon daughters which are particles that result of the radioactive decay of radon gas
5 AIR TESTING EQUIPMENT: SO MANY CHOICES Given these contaminants, what I hope you will gain from our time together today is how to choose the best air testing equipment for your application.With so many choices in equipment, my best overall advise to you is to FIRST step back and ask some simple questions:-WHY ARE TAKING THE AIR SAMPLE?-WHAT ARE YOU GOING TO DO WITH THE RESULTS?
6 CHOOSE YOUR EQUIPMENT: BASED ON YOUR OBJECTIVES Survey Tool-a direct-reading device that will provide immediate indications of chemical levels in the field. Immediacy of results override limitations in accuracy.Validated Method-air sample collection followed by laboratory analysis. Accuracy of results override delay in obtaining results.And then choose your equipment, based on your objectives.In general, air testing equipment can be classified as either:-survey tool OR-validated methodExplain each from slide.
7 CHOOSE YOUR EQUIPMENT: BASED ON YOUR OBJECTIVES Applications for Survey Tools-Leak Detection, Confined Space Entry, Hazmat Response, Initial Screening and Spot Checks of Personal Exposure LevelsApplications for Validated Methods-Compliance with Government Regulations, Measurement of Highly Toxic Compounds, and Measurement of Compounds for which direct-reading survey tools do not exist.There are applications where either a survey tool or a validated method would be the best option.Read lists.
8 SURVEY TOOLS OPTIONS AND APPLICATIONS So let’s first take a look at specific SURVEY TOOLS along with the applications for each.
9 GENERAL CATEGORIES OF SURVEY TOOLS ColorimetricTechnologiesDetector TubesColor BadgesColorimetric WipesColorimetric SwabsSensorTechnologiesCatalyticPhotoionizationElectrochemicalLight-ScatteringIn my opinion, there are 2 general categories of survey tools. Those based on colorimetric technologies and those based on sensor technologies.
10 SURVEY TOOLS COLORIMETRIC TECHNOLOGIES We’ll begin by reviewing the options using colorimetric technologies.
11 DETECTOR TUBES A FIRST LINE OF DEFENSE Classical measurement technique with first patent in 1919Glass tube containing a chemical media that reacts with the contaminant of interest by changing colorConcentration is read directly from a printed scale on the tubeTubes now available for measurement of over 200 gases/vaporsFirst, colorimetric detector tubes.I would guess that this is the first device most of ever used when learning to do air sampling. It is was surprising to me to learn that this technology has actually been around since 1919.Since that time, tubes have been continuing developed and colorimetric tubes are now available for measurement of over 200 gases/vapors.
12 TYPES OF DETECTOR TUBES GRAB SAMPLE TUBES Used with a hand-operated pump to collect on-the-spot measurementsMeasurements typically take a few minutes to completePump and tube are calibrated by themanufacturer as a unitAs the technology advanced, various types of colorimetric detector tubes were developed. The most commonly used detector tubes are described as short-term or grab sample tubes. I assume everyone here has used these tubes.One issue that seems to come up frequently is whether different brands of tubes can be used with different brands of pumps. Personally, I do not recommend this. The pump and tube are calibrated by the manufacturer of the unit. Even if the air volume is the same, the flow dynamics are different from pump to pump that can affect color chemistry. Piston vs Bellows.
13 LATEST DEVELOPMENT OF DETECTOR TUBE TECHNOLOGY CHIP MEASUREMENTSYSTEM (CMS)Chemical-specific capillary tubes using same technology as short-term tubes10 tubes on a chipUsed with an electronic analyzer with internal pump and data recorderIn more recent years, Draeger has released a new development in the short-term tube technology called the CMS.Read slideSKC 802-series
14 APPLICATIONS GRAB SAMPLE TUBES AND CMS QualitativeLeak DetectionChemical MigrationConfined Space Entry (using extension hose)Unknown Identification(using HazMat kits)Semi-quantitativeSpot checks of area or breathing zone samplesMaximum levels during various processes or worker activitiesAnalysis of sample bags containing air emissionsReview each and highlight analysis of bags with air flowing under pressure.
15 TYPES OF DETECTOR TUBES PASSIVE TUBES Break open one end and place in designated holderSample from 1-10 hoursLength of stain indicates air concentration in ppm-hrDivide by hours sampled to obtain ppm concentrations in airA further development of the long-term detector tubes are passive color tubes that are used for 8 or even 10 hour sampling WITHOUT any pump—hand operated or battery operated.Review slide.
16 TARGET COMPOUNDS PASSIVE COLOR TUBES Acetic AcidAmmoniaButadieneCarbon DioxideCarbon MonoxideEthanolHydrochloric AcidHydrocyanic AcidHydrogen SulfideNitrogen DioxidePerchloroethyleneSulfur DioxideTolueneTrichloroethyleneThere are a lot MORE options using the passive tubes. One very popular application is for CO.Cheap, easy way to sample gaseous emissions. In general industry, they are used a lot for forklift drivers.Additional passive color tubes available from Gastec.
17 SOURCES OF ERROR DETECTOR TUBES Accuracy is limitedInterfering compounds cause similar reactions and readings on tubeAffected by temperature and humiditySubjective differences in “eyeballing” the color change to determine resultDetector tubes are considered a SCREENING TOOL because they do have some inherent sources of error:Read slide
18 COLOR BADGES IMMEDIATE VISUAL INDICATORS Badges contain a chemically coated filter paper or “indicator layer”.Target chemicals in air react with the chemical coating used in the badge and produce a color change.This change is a visual indicator to the worker that an exposure has occurred.Color comparison charts allow for exposure estimates.Now we’ll discuss colorimetric BADGES. These badges are typically worn as personal samplers and they contain…Read slide.
19 APPLICATIONS COLOR BADGES Visual indication to evacuate work area in presence of dangerous chemicalsSemi-quantitative exposure level screeningLeak DetectionWarning for EscapeOne of the biggest application for this technology is to give a visual indication when working around highly toxic chemicals like phosgene.My employer, SKC, does not manufacture color badges, but I really like the K and M Environmetal design. When exposed to a highly toxic chemical, an exclamation point appears on the badge.So your co-worker can EXCLAIM “run for your life”.
21 SOURCES OF ERROR COLOR BADGES Limited accuracy for quantitative measurements using “dose estimators”Cross-sensitivities with other chemicalsTemperature and humidity effectsUV light may discolor indicatorThe unique source of error with this technology is the fact that UV light may discolor indication over time.
22 COLORIMETRIC WIPES FOR CHEMICALS ON SKIN/SURFACES Chemicals in air will eventually deposit on skin and surfaces and may pose a risk to workers by skin absorption or ingestion.Chemical residue on shoes, lunch boxes, and other personal items may inadvertently become a take-home toxin for worker’s family members.I know this is supposed to be a presentation on AIR sampling, but…
23 FULL DISCLOSURE WIPES FOR LEAD ON SKIN OR SURFACES Developed by US NIOSH; NIOSH Method 9105Licensed for production by SKCBehavior modification tool-Allows workers to determine if their washing/decontamination has been effective.Can identify down to 18 ug of leadIt’s common knowledge that lead on skin or surfaces can be TOXIC.To address this concern, NIOSH developed a field detection kit and licensed it to SKC for commercial production.Read slide.
25 COLORIMETRIC SWABS FOR LEAD IN PAINT AND SURFACES Self-contained sampling swabs for rapid screening of lead in paint and on surfacesSqueeze the swab to release the test reagents and then wipe the surface with the swabObserve color changeColorimetric swabs also exist for testing lead and other contaminants on surfaces. You can even buy these now at Home Depot and Walmart.Read slide.SKC
26 SOURCES OF ERROR COLORIMETRIC WIPES AND SWABS Cross-sensitivitiesExtremely heavy soiling or other contaminants on the test surface may interfere with color developmentPersons with color blindness may not be able to detect the color development.Like with color detector tubes, colorimetric wipes and swabs have sources of error which limit their accuracy.
27 SURVEY TOOLS SENSOR TECHNOLOGIES Now on to survey tools that employ sensor technologies.
28 CATALYTIC SENSORS COMBUSTIBLE GAS MONITORS Commonly used since 1959Test gas or vapor is heated to combustion (burned) and the instrument translates the resulting increase in temperature/resistance as a percentage of the lower explosive limit (LEL).Oxygen (>10%) is required for the catalytic sensor to operate properly.One of the most popular direct reading instrument using sensor technologies are combustible gas monitors that employ a catalytic sensor.In the most simplistic of terms, the principle of operation is that the test gas/vapor is BURNED to produce the reading. Therefore, oxygen is required for this instrument to function properly.
29 APPLICATIONS CATALYTIC SENSORS Non-specificmeasurement of high,explosiveconcentrationsof gases/vapors in air:Confined space entryEmergency responseHandheld 5-Gas Monitor including catalytic LEL sensorSKC 805-series
30 SOURCES OF ERROR CATALYTIC SENSORS Poisoning or degraded performance can occur when sensor is exposed to certain compounds such as lead-containing compounds, silicones, sulfur-containing compounds, and halogenated hydrocarbons.Oxygen deficient environments will cause the instrument to produce erroneous readings.Some of you may be thinking: HEY, why do you consider this a survey tool as we use this in life/death situations.Well, it is considered a survey tool since it is possible for the instrument to produce erroneous results.Read slide
31 PHOTOIONIZATION DETECTORS BROAD SPECTRUM VOC MONITORS Based on the principle that some chemicals can be ionized when hit with high-energy UV light. The instrument measures the resulting current which is proportional to concentration of the gas/vapor in air.Instrument manufacturers publish technical documents with lists of chemicals that can be detected using UV lamps with various energy levels.Another very popular survey tool is a PID.In this case, the test gas/vapor is hit with high-energy UV light which ionizes it producing current of an amount proportional to concentration.These are widely used as broad spectrum monitors for organic chemicals.
32 APPLICATIONS PHOTOIONIZATION DETECTORS Non-specificmeasurement of ppmconcentrationsof gases/vapors in air:Leak DetectionPersonal ExposuresSpill DelineationHazMat ResponseSKC 730-series
33 SOURCES OF ERROR PHOTOIONIZATION DETECTORS Non-specific-can not identify specific VOCDoes not detect all VOCs or compounds such as carbon monoxide, hydrogen, methane, oxygen, and formaldehydeHumidity can cause lamp fogging resulting in lower readingsSensor drift
34 ELECTROCHEMICAL SENSORS SPECIFIC TO TARGET COMPOUNDS Contain components designed to react with a specific gas or vapor. The reaction generates a current which is translated into concentration in air.Sensors available to measure about 20 compounds in the ppm range.Some cross-sensitivities can occur from other compounds.Electrochemical sensor technologies are available to measure specific target compounds. After spending more than 25 years in this profession, I am really disappointed that we only have electrochemical sensors for about 20 compounds.
35 APPLICATIONS ELECTROCHEMICAL SENSORS Measurement of ppmconcentrationsof target gases/vapors inair:Leak DetectionPersonal ExposuresConfined Space EntrySpill DelineationHazMat Response5-gas monitorThese sensors are widely used in single and multi-gas instruments for a number of applications.Single-gas monitor
36 SOURCES OF ERROR ELECTROCHEMICAL SENSORS Cross-sensitivitiesSensor performance and lifetime can be affected by very dry or very humid environments or by brief exposures to high concentrations
37 AEROSOL PHOTOMETERS MEASURE AIRBORNE DUST LEVELS A light beam is shined through air containing particulate matter. The particulate matter scatters the light beam and the amount of light scattering is measured on a photocell and displayed as mg/m3 concentrations.Commonly known as “light scattering” instrumentsNext, we will discuss sensor technologies for particulate contaminants. You may know these devices as “light scattering instruments” but the technical term actually is “aerosol photometer”.Sunbeam pouring in through a window.
38 APPLICATIONS AEROSOL PHOTOMETERS Screening tool evaluating personal dust levelsPerimeter samplingInternal dataloggers allow for TWA or peak determinationsInternal pumps allow for concurrent sample collection using filtersHazDust IVSKC
39 SOURCES OF ERROR AEROSOL PHOTOMETERS Test dust does not produce the same results as the calibration dust; correction factor needs to be determined.Does not respond to fibrous dusts like asbestos or to small ultrafine dusts.Note: Most are not intrinsically safe.
40 CALIBRATION IS CRITICAL FOR SENSOR TECHNOLOGIES All direct-readinginstruments must becalibrated properly andregularly.Both factory and usercalibrations are required.
41 VALIDATED METHODS WITH LABORATORY ANALYSIS OPTIONS AND APPLICATIONS
42 VALIDATED SAMPLING METHODS WITH LABORATORY ANALYSIS Published by government or other scientific agenciesDefine all the critical sampling parameters for accurately measuring exposures of specific chemicalsMost reliable means of evaluating exposures, but lab analysis takes timeSome of you may be wondering, what are validated sampling methods.These are SCIENTIFIC DOCUMENTS…Not analyzed in the field, they are analyzed in an analytical chemistry lab.
43 WEBSITES FOR GOV’T AGENCY METHODS NIOSH MethodsOSHA MethodshtmlThe Bible of Air Sampling in the Workplace.I reference these methods every day of my working life and so does Susan.
44 HELP FROM SKC: SAMPLING GUIDE IN SKC CATALOG Lists all regulated chemicalsIncludes:Agency Method NumberSampling Details such as Flow Rate, Time, VolumeAnalytical methodSample collection media and SKC catalog number
45 SKC SAMPLING GUIDE APP Free download of the SKC Sampling Guide App for Apple or Androiddevices.Visit SKC homepage atand lookfor link for mobile devices.
46 TYPES OF SAMPLES USING VALIDATED METHODS Active Samples-Require the use of (3) key elements: Pump, Sample Collection Media, Pump Calibrator (Flowmeter).Passive Samples-Require the use of a passive sampler (badge) that has been thoroughly tested to ensure sampling reliability under various field conditions.In general terms, there are two types of samples using validated methods:Explain (3) components of active sampling.(Focus only on “validated” passive samplers here.)
47 DEFINING PASSIVE SAMPLING The collection of airborne gases and vaporsat a rate controlled by the physical process ofdiffusion WITHOUT the use of a samplingpump to actively pull air through the samplecollection media.Everybody understands active sampling means using a pump so let’s take a minute to look at the definition of passive sampling.
48 DEFINING PASSIVE SAMPLING Chemicals diffuse froman area of highconcentration in the air toan area of low concentrationon the sampler.Based on their mode ofsample collection, passivesamplers are also referredto as diffusive samplers.The uptake or sampling rate for individual chemicals must be supplied by the manufacturer of the sampler or the agency that published the validated method.
49 VALIDATED SAMPLING METHODS GASES AND VAPORSWith that introduction, let’s take a look at the validated sampling methods for typical gases and vapors in mining operations.
50 ACTIVE AIR SAMPLING: USING SORBENT TUBES Glass tubes containing a sorbent materials are used to trap designated compounds for lab analysis.Contaminants are ADsorbed onto the surface of the sorbent material and then DEsorbed for laboratory analysis.The reference method or the gold standard of active sampling involves the use of sorbent tubes.Contaminants are ADsorbed onto sorbent material and are then DEsorbed for laboratory analysis.It always disappoints me afte a training class when someone asks me if SKC sorbent tubes are a competitor to Draegr detector tubes.NO, the technologies go hand-in-hand.Sorbent Tube
51 SORBENT TUBE SAMPLING: FOR ORGANIC SOLVENTS Sorbent: Activated CharcoalSpecified in government methods for the collection of common organic compounds including benzene, toluene, and xyleneHigh adsorptive capacityDerived from coconut shells
52 SORBENT TUBE SAMPLING: FOR GASEOUS EMISSIONS Sorbent: Chemically-coated adsorbentmaterialsSpecified in government methods for the collection gaseous emissions such as nitrogen oxides and formaldehydeContaminants react with the chemical coating and produce a stabile compound for analysis.Example: Nitrogen dioxide is collected using a tube containing carbon molecular sieve sorbent that is chemically-coated with triethanolamine (TEA).The method will specify the sorbent tube and the SKC catalog will specify the catalog number of the media based on the method.
53 ACTIVE AIR SAMPLING USING SAMPLE BAGS Used to collect grab samples of an air-contaminant mixture into a flexible container for subsequent analysisMining applications include methane, carbon monoxide, and organic solvent vapors.-Some contaminants like methane and CO will not “stick” to any sorbent material. So to trap the contaminant, you have to place a sample of the air into a sample bag.-Some times you want to just place the air-contaminant mixture into a container where it can then be easily and rapidly squeezed out into a laboratory instrument for analysis.
54 SAMPLING WITH BAGS TYPES AND APPLICATIONS TEDLAR® OR SKCFLEXFILM BAGSTypically used for the collection of organic vapors.Designed for short-term storage of up to 1-2 days prior to analysis.ALUMINIZED OR SKCFLEXFOIL™ BAGSTypical mine applications include methane and carbon monoxide.Can store samples up to 5 days prior to analysis.
55 SAMPLING WITH BAGS SAMPLE COLLECTION OPTIONS Positive PressureNegative Pressure
56 ACTIVE AIR SAMPLING USING CHEMICALLY-COATED FILTERS Filters are used as a substrate for liquid media that can trap contaminants.Liquid media will react with the contaminant of interest producing a stabile compound for storage and analysis.Mining applications include isocyanates such as TDI and MDI.Another sampling option has been growing in demand in recent years and that is active sampling using chemically-coated filters.
57 SAMPLING TRAIN WITH COATED FILTERS SKCfor TDI or HDI
58 PASSIVE AIR SAMPLING: FOR ORGANIC SOLVENTS Validated sampling methods for organic solvents specify the use of passive samplers containing charcoal sorbent.Methods allow the use of passive samplers for use in collecting 8-hr TWAs or 15-min STELs.Health and safety professionals and workers LOVE the convenience of passive air sampling.The good news is that in recent years, US OSHA has been validating these devices for specific compounds.Methods allow…SKC 575-series
59 OSHA PASSIVE SAMPLING METHODS: FOR ORGANIC SOLVENTS Toluene by OSHA 111Tetrachloroethylene and Trichloroethylene by OSHA 1001Xylenes and ethyl-benzene by OSHA 1002MEK and MIBK by OSHA 1004Benzene by OSHA 1005
60 PASSIVE AIR SAMPLING: FOR FORMALDEHYDE Validated OSHA Method 1007 specifies a passive sampler that contains a chemically-treated filter paper.Formaldehyde combines with chemical to form a stabile compound for lab analysis.OSHA validated passive samplers using a chemically treated filter paper are also available for formaldehyde. The principle of operation is similar to the coated filters used with a pump, but these are passive.SKC UMEX badge shown here has been validated by US OSHA in Method 1007 for formaldehyde.SKC
61 VALIDATED SAMPLING METHODS PARTICULATESIn this application, a filter of a:SPECIFIC TYPE AND PORE SIZEAre used (like a sieve) to trap the contaminant of interest.
62 DEFINING PARTICULATE CONTAMINANTS TOTAL DUSTParticulate matter,both respirable andnonrespirable, that canbe trapped onto thedesignated filter loadedinto a cassette.RESPIRABLE DUSTParticulate mattersmall enough in size topenetrate deep into the lungdown to the gas exchange(alveolar) region.Particulate contaminants have been traditionally defined as either total dust or respirable dust.Respirable dust includes those very small particles that can penetrate down deep in to the lung. While total dust includes both the small respirable and larger dust particles.
63 TOTAL DUST VS RESPIRABLE DUST SAMPLERS The sampling equipment for total and respirable dust sampling is similar. The only difference is a size-selective device namely a cyclone is placed on the inlet of the filter for respirable dust sampling.Total Dust SamplersRespirable Dust Samplers
64 AIR SAMPLING FOR PARTICULATES IN MINING OPERATIONS Air sampling is done usingfilters loaded intocassettes WITHOUTcyclones for:MetalsAsbestosRadon DaughtersAir sampling is done usingfilters loaded intocassettes WITHcyclones for:Respirable Crystalline Silica and Coal DustDiesel Particulate Matter (DPM)When deciding whether to use a cyclone or not, you should review how the contaminant is regulated and the specifications of the published method.Read slide
65 TOTAL DUST SAMPLING TIP The filter-cassette is clipped on the worker’s lapel in the breathing zone with the inlet of the sampler pointing downwards—just like your nose.Remove the small plug only from the inlet.Watch for filter overloading.
66 AIR SAMPLING: FOR ROUTINE METALS Most metals can be collected onto 37-mm, 0.8 um pore size MCE filters.The Metal/Nonmetal Inspection Handbook recommends a pump flow rate of 1.7 L/min.Laboratory chemical analysis of the filter can determine the type of metals and amount present in air.
67 AIR SAMPLING: FOR HEXAVALENT CHROMIUM Some metals such as hexavalent chromium (Cr+6) will require alternative sampling media and special sample handling procedures.Cr+6 sampling requires the use of a 5 um pore-size PVC filter at a typical flowrate of 1.7 L/min.Filters should be removed from the cassette, placed into vial, and rushed to the laboratory.
68 AIR SAMPLING: FOR HEXAVALENT CHROMIUM Samples are rushed by overnight shipment to the laboratory because interfering compounds in the test atmosphere can cause the collected Cr+6 to convert to Cr+3 upon storage.Interfering compounds include Fe+2 in welding applications.
69 AIR SAMPLING: FOR OTHER SPECIALTY METALS Other specialty metals such as silver, calcium, and mercury use the standard MCE filter for sampling, but require the use of a separate filter/cassette due to special handling in analysis.It is imperative that you communicate with your analytical laboratory PRIOR to sampling to ensure proper procedures are followed.
70 AIR SAMPLING: FOR METALS IN WELDING MSHA advises that the filter-cassette sampler should be positioned beneath the welder’s helmet when the helmet is placed down.A convenient welding helmet adapter has been developed by a Canadian agency for this application. Leather straps and flexible metal in the tubing allow for easy cassette placement.
71 WELDING HELMET ADAPTER Note also 25-mm cassette can be used instead of 37-mm cassette.SKC
72 REGULATORY NEWS: ASBESTOS Effective April 2008, MSHA issued a new PEL for asbestos of 0.1 fiber/ml of air, reduced from 2 fibers/ml.A new excursion limit of 1 fiber/ml for 30 minutes was also issued.The MSHA exposure limits for asbestos are now consistent with those issued by OSHA.
73 AIR SAMPLING: FOR ASBESTOS Asbestos samples are collected using 25-mm, 0.8 um pore size filters loaded into black, conductive cassettes.The filter cassettes have a cylinder cowl as the middle section that protects the filter and ensures a uniform fiber deposition.The cowl should point downwards when sampling and the cassette inlet piece should be removed to allow for open-face sampling.Keep in mind, the analysis method is MICROSCOPY. So this cowl, protects the filter from fingerprints and gives even deposition.
74 AIR SAMPLING: FOR ASBESTOS After sampling, filters are analyzed microscopically so filter loading is critical.For full-shift sampling, the Metal/Nonmetal Inspection handbook recommends a flowrate of 1.7 L/min for air volumes of L.For short-term sampling of minutes, flowrates of 1.7 L/min to 2.5 L/min or higher are recommended for optimal filter loading.
75 AIR SAMPLING: FOR RADON DAUGHTERS Pump and filter sampling is done at a flow rate of 2 L/min using 25-mm glass fiber filters loaded into a cassette holder as shown.The filter is placed in the holder with the semi-smooth “waffled” pattern facing the pump and the rough side exposed to the air.Collect a 5-minute sample and count the sample using a radiation counter within 90 minutes.
76 WHY USE A RESPIRABLE DUST SAMPLER ? Some air contaminants such as silica are regulated as respirable dust. Collecting larger, non-respirable particulates would inflate the results overestimating exposure.
77 CYCLONES: TRADITIONAL RESPIRABLE DUST SAMPLERS Cyclones are named for the rotation of air within a chamberFunction on the same principle as a centrifugeUse centrifugal force to separate particles according to their aerodynamic diameter
78 CYCLONE OPERATIONAir enters through a slit on the side of the sampler which creates cyclonic action.Large particles fall into red “grit pot” and are discarded.Small particles are thrown onto the filter for analysis.Cap must be in place.
79 DIFFERENT CYCLONE OPTIONS All cyclones are not created equal!Each cyclone has different operating specifications and performance criteria.Be sure you know the flow rate specified to achieve the desired cut-point before using a cyclone.
80 A NEW RESPIRABLE DUST SAMPLER FROM SKC SKC has developed an impactor based sampler for respirable dust called the Parallel Particle Impactor or PPI.Single-use,disposable PPI models are available for use at either 2, 4, or 8 L/min.
81 SKC RESPIRABLE PPI: FUNCTIONALITY The disposable models of the PPI look and function very much like a traditional 37-mm cassette.But the inlet comes pre-loaded with size-selective impactor plates that scrub out the non-respirable portion.PPI samplers are smaller than traditional cyclones and can fit under a welder’s helmet or other PPE.SKC calls this sampler a Paralled Particle Impactor or PPI and here you can see the operating principle.Read bullets.Note that you are NOT concerned about how much particualte is collected at each of the individual inlets, but only what is collected on the final filter.This is a precise match to the current collection efficiency curves.
82 50% CUT-POINT: A PERFORMANCE SPECIFICATION The 50% cut-point is often used to describe the performance of respirable dust samplers including cyclones.It is the particle size that the device can collect with 50% efficiency.Particles smaller than the 50% cut-point of the cyclone are collected with an efficiency greater than 50%.Larger particles are collected with an efficiency less than 50%.
83 RESPIRABLE DUST SAMPLERS: CURRENT U.S. CRITERIA Existing U.S. MSHA and OSHA regulations specify the use of respirable dust samplers with a 50% cut-point of 3.5 um.But in 2013, OSHA issued a proposed rulemaking for respirable crystalline silica specifying the use of samplers with a 50% cut-point of 4.0 um. This is consistent with NIOSH, ACGIH, and other organizations.
84 CYCLONE CALIBRATION TIP Cyclones can be placed inside calibration jars to measure the flowrate through the inlet.Take care when using calibration jars with piston-style calibrators such as the DC-Lite or Defender.SKC
85 CYCLONE CALIBRATION TIP: PISTON STYLE FLOWMETERS The “dead” volume in the jarcan affect the rise/fall of thepiston causing the readings tobe erroneously low.Options:Use calibration adapters if available.Attach cyclone to calibrator pressure port and pump to suction port.Use smallest calibration jar possible.SKC
86 CYCLONE SAMPLING TIP: SAMPLER CLEANING Failure to clean the cyclone after sampling canaffect size-selection on future samples:After sampling, clean all parts of the cyclone, with mild soapy waterDon’t forget to clean the grit pot.Dry the cyclone. (Air-dry or blow-dry)Wipe with a dust-free tissue or wipe with an isopropyl alcohol moistened pad.Caution: Do not use strong solvents to clean plastic cyclones
87 DIESEL PARTICULATE MATTER (DPM) MSHA issued a final rule on DPM for underground metal/non-metal miners effective May 2008.PEL is 160 ug/m3 as Total Carbon: Elemental Carbon plus Organic Carbon(EC + OC).
88 AIR SAMPLING: FOR DPMMSHA requires that DPM samples be collected using a specialty filter cassette. (SKC ).This filter cassette contains an internal impactor plate that separates DPM from other respirable particulate based on size.Larger respirable particles impact and are removed while DPM particles collect onto the heat-treated quartz filter.
89 DPM filter cassette-SKC Cat. No. 225-317 Note that SKC features the GS-1 cyclone with the DPM sampler on the right hand column of page 89. This is because the GS cyclone with the single inlet is a close match to the Dorr-Oliver nylon cyclone. At this time, the only cyclone that can be used by US MSHA inspectors is the Dorr-Oliver or “an equivalent”.For your applications, any cyclone that can be attached to the DPM filter cassette can be used. It is only scrubbing out the large particles so they do not overload the filter.
90 DPM SAMPLING TRAIN Cyclone Removes non-respirable particles that may overload the filterInternal Impactor Plate in CassetteRemoves respirable particles greater than 1.0 um in diameterAfter-filter assemblyCollects DPM particles less than 1.0 um in diameter for analysis of EC and/or OC.
91 AIR SAMPLING: FOR DPMSamples are collected at 1.7 L/min or 2.0 L/min for the full-shift.Again, it is important not to invert the sampler during the sampling period.After sampling the filters are sent to the laboratory for analysis following NIOSH Method 5040.
92 AIR SAMPLING METHODS SKC CAN HELP So many contaminants, so many choices….SKC CAN HELP