Basic Air Monitoring Bureau of Workers Comp PA Training for Health & Safety (PATHS) PPT-045 -01 1
Program Purpose • Various means of detection exist for solids, liquids and gases. • This program is an overview of monitoring the means to be used in some safety applications or to aid in responding to an event. PPT-045 -01 2
Main Topics • Hazards • Chemical and physical properties of target materials • Some gas properties • Resources • Propane as an example Detector types Calibrating detectors Field monitoring Sewer entry policy as an example • Working a situation • Bibliography • • PPT-045 -01 3
Hazardous Atmospheres Residential • • CO (carbon monoxide) Gas leaks into buildings Radon Intruding emissions from adjacent properties PPT-045 -01 4
Hazardous Atmospheres Industrial • Process areas • Storage locations • Gas leaks • Flammable liquid spills • Drums and containers • Special activities • Hazardous material events PPT-045 -01 5
Municipal Operations • Water treatment plants • Sewer plant operations • Valve pit work • Garage work PPT-045 -01 6
Specific Field Work • Confined space • Trenching and shoring PPT-045 -01 7
Environmental Issues • Clean air determinations • Emissions control • Waste sites PPT-045 -01 8
Emergency Response • Industrial rescue or hazardous materials response • Emergency services PPT-045 -01 9
Hazardous Atmospheres • Special types of atmospheres • Carbon monoxide • LGP/LNG • Radon • Hydrogen sulfide • Carbon dioxide • Specialty gases • Radiological concerns • Other potential hazards PPT-045 -01 10
Basic Air Monitoring • Each of the previous situations could benefit from air monitoring. • Detectors are generally used to determine: – Oxygen content – Presence of flammable vapors or gases – Presence of toxic materials • Terms pertaining to characteristics of materials for which monitoring might be used should be discussed first. PPT-045 -01 11
Hazard Property Terms • IDLH: Immediately dangerous to life and health values • Exposure Limits: OSHA PEL: permissible exposure limits • TWA: Time weighted average limits expressed in PPM which should not be exceeded during an 8 -hour work shift in a 40 -hour work week • PPM: Parts per million. Can be converted into percentage by volume by dividing the PPM given by 10, 000. PPT-045 -01 12
Chemical & Physical Properties • MW: Molecular weight will help you determine if the vapor or gas is heavier or lighter than air; the vapor density. • Vapor density can be determined by dividing the material’s molecular weight by 29: MW 29 PPT-045 -01 13
Vapor Density • A comparison of a gas or vapor’s weight to air • Air is assigned a vapor density of 1. 0 • Gases or vapors with a vapor density greater than 1. 0 are that many times heavier than air. • Gases or vapors with a vapor density less than 1. 0 are lighter than air. • This will help you determine if you will monitor high or low in an area to obtain a reading. • May also be expressed as RGas. D: relative gas density PPT-045 -01 14
Flashpoint Temperature Fl. P. : Flashpoint • The lowest temperature at which vapors are produced by a liquid that, when ignited, will flash • No continued combustion at this temperature • Sustained burning is at the fire point (temperature above the flashpoint temperature) PPT-045 -01 15
IP • IP: Ionization potential in electron volts (e. V) for a vapor or gas • This will signify a photoionization detector may be used to detect the presence of material • Lamp rating must be at or greater than IP of test gas or vapor for a precise reading PPT-045 -01 16
Hazard Characteristics • Before starting, fully understand the hazards of the material for which you’ll monitor: • • • Vapor density Flammable limits Health hazards Exposure limits Signs and symptoms of exposure PPT-045 -01 17
RGas. D • RGas. D: Relative gas density will indicate if gas/vapor is heavier or lighter than air • If we divide the MW by 29 (the weight of air) this should also approximate the vapor density of the gas/vapor PPT-045 -01 18
Gas/Vapor Behavior • Gases can stratify in air based on their vapor density • Take readings from various depths and points in below-grade situations • You may need to take readings in rooms at different elevations and points as well PPT-045 -01 19
LEL/UEL • UEL/LEL: Upper and lower explosive limit • Range in between is the flammable range • Safety Rule of Thumb Monitor until you find 10 percent of the LEL inside a building • Outside: stop when you determine 20 percent LEL is evident PPT-045 -01 20
UEL/LEL • Will aid in determining the perimeter and extent of gas/vapor spread (100 percent of LEL, dangerous) • Only ignition source needed to ignite gas/vapor • You do not want to be within a flammable environment! PPT-045 -01 21
Respirator • NIOSH Respirator recommendations assist in determining the level of needed respiratory protection depending upon the PPM (Mg/M 3) for a material PPT-045 -01 22
Asphyxiation Hazards • Simple Asphyxiants: Displace breathable oxygen in an area (example: carbon dioxide) • Chemical Asphyxiants: Bond with red blood cells and restrict the body’s ability to metabolize oxygen (examples: carbon monoxide and hydrogen cyanide) PPT-045 -01 23
Some Gas Particulars Gas Carbon Monoxide LEL% (10%LEL) 12. 5 Hydrogen Cyanide 5. 6 Hydrogen Sulfide LPG IDLH PPM IP % 1. 25 1, 500. 15 13. 98 . 56 50 . 005 13. 6 4. 3 . 43 300 . 03 10. 46 1. 9. 19 19, 0001. 9 in e. V PPT-045 -01 10. 95 24
Carbon Monoxide • • • IDLH PEL IP RGas. D LEL UEL 1200 ppm TWA 50 ppm 14. 01 e. V. 97 12. 5% 74% PPT-045 -01 25
LPG/LNG • • IDLH PEL IP RGas. D LEL UEL Sa/SCBA 2000 PPM (10% LEL) 1000 PPM 10. 95 e. V 1. 45 – 2. 0 2. 1% (propane) 1. 9% (butane) 9. 5% (propane) 8. 5% (butane) 2000 PPM PPT-045 -01 26
Hydrogen Sulfide • IDLH • PEL • • • 100 ppm C 20 ppm* 50 ppm (10 min max peak) IP 10. 46 e. V RGas. D 1. 19 LEL 4. 0% UEL 44. 0% Sa/SCBA 100 ppm *C=ceiling level value PPT-045 -01 27
Carbon Dioxide • IDLH • PEL • • IP RGas. D LEL/UEL Sa/SCBA 40, 000 ppm (4%) TWA 5000 ppm (. 5%) 8 hours 13. 77 e. V 1. 53 Non-flammable gas Yes PPT-045 -01 28
Carbon Dioxide CO 2 % By Volume 0. 5 1. 0 1. 5 2. 0 3. 0 4. 0 5. 0 6. 0 7. 0 Max Exposure Limit, Minutes Indefinite 480 60 20 10 7 5 Less than 3 A Total Flood carbon dioxide system will displace the breathable oxygen and asphyxiate those inside Compressed Gas Assn. Handbook, 3 rd Ed, page 293 PPT-045 -01 29
Other Potential Hazards • Caution: Many materials have several hazards associated with them. • Some may be flammable and possess poisonous characteristics. • Toxic and corrosive gases may be encountered. • Example: Hydrogen sulfide (H 2 S) deadens the sense of smell and may falsely lead someone to think it has dissipated. (LEL and UEL are 4 percent to 44 percent, respectively - flammable and poison) PPT-045 -01 30
Specialty Gases • Boron trichloride • Diborane • Phosphine • Silane Radiological Hazards • Radon • Industrial events PPT-045 -01 31
Action Levels • Assigned by policy • When a given level is read, personnel are warned to take action or to leave the area • 29 CFR 1910. 146 for confined spaces. 10 percent LEL: permit revocation • Determine action levels for gases/vapors you may encounter PPT-045 -01 32
Resources • Safety Data Sheets (SDS) • NFPA standards (National Fire Protection Association) • NFPA Fire Protection Handbook PPT-045 -01 33
Resources Technical manuals: Sax’s “Dangerous Properties of Industrial Materials” Emergency guides: “Emergency Response Guidebook” Each cited source has valuable information toward monitor planning PPT-045 -01 34
Resources • “NIOSH Pocket Guide to Chemical Hazards” • The following slides give an overview of the NIOSH categories to aid in your monitoring operations PPT-045 -01 35
NIOSH Information Categories Name of material Formula CAS# RTECS# IDLH Conversion: PPM to Mg/M 3 • Synonyms/trade names • • Exposure Limits • Measurement methods • Chemical and physical properties • PPE • Respirator recommendations PPT-045 -01 36
NIOSH Categories • Incompatibilities and reactivities • Exposure routes, symptoms, target organs • First aid PPT-045 -01 37
Propane as an Example • Using Selected Categories: – Formula: CH 3 CH 2 CH 3 – CAS#: Chemical abstract service number 74 -98 -6 – RTECS#: Registry of toxic effects of chemical substances TX 2275000 – IDLH: 2100 PPM (10% LEL) – Conversion: 1 ppm = 1. 80 mg/m 3 – OSHA PEL: TWA 1000 PPM (1800 Mg/M 3). 1000 PPM/10, 000=0. 1 percent PPT-045 -01 38
Propane as an Example • Physical Description • MW (Molecular Weight): 44. 1 (44. 1/29=1. 52 vapor density) • Fl. P (Flashpoint): NA (Not applicable due to being a gas) • IP (Ionization Potential): 11. 07 e. V. A photoionization detector could be used to detect propane as long as the lamp used has an ionization energy greater than the IP of the material PPT-045 -01 39
Propane • RGas. D: Relative gas density; heavier or lighter than air • Propane has an RGas. D of 1. 52 making it 1. 52 times heavier than air • Monitor low in an area • Propane is a hydrocarbon and will “huddle” in confined areas • Always be thorough in your monitoring PPT-045 -01 40
Propane • UEL/LEL: 9. 5 percent to 2. 1 percent. If monitoring to stop when 10 percent by volume is found, 10 percent of the LEL of 2. 1 percent is. 21 percent • Respirator recommendations for propane: (NIOSH) SA (supplied air) and/or SCBA (selfcontained breathing apparatus) at or above 2100 PPM PPT-045 -01 41
Detectors • • • General types include: Passive badges and dosimeters Tubes/pumps Combustible gas indicator (CGI) Single gas Multiple gas Flame ionization detector (FID) Photoionization detector (PID) Radiological PPT-045 -01 42
Dosimeters • Passive Monitors Permeation of gases through a membrane onto a collection medium • Film Badge Desorbed with carbon disulfide Analyzed by gas chromatograph *Air Monitoring for Toxic Exposures, ” Shirley A. Ness, Van Nostrand Reinhold, 1991, page 85 PPT-045 -01 43
Tubes • Test atmosphere is drawn into tube • Tubes are gas/vapor specific • Presence of gas/vapor changes reagent color in tube • PPM and percentage gradients on tube indicate amount of gas/vapor in atmosphere PPT-045 -01 44
Tubes and Pumps • Specific number of pump strokes required for precise reading if using a manual pump • Pump assemblies are calibrated to draw either 50 cc or 100 cc on each stroke when set PPT-045 -01 45
Solid State Sensors Semiconductors can be used for: – General survey monitors – Specific gases and hydrocarbons – Toxic gases • Reads electrical resistance decreases across a Wheatstone bridge PPT-045 -01 46
Combustible Gas Indicators • Also called CGIs • Catalytic combustion • Voltage drop is read across a Wheatstone bridge PPT-045 -01 47
Single Gas • Sensor is gas-specific • Electro-chemical principle • Chemical specificity is due to electrodes and electrolytes used • “Ticker” used by gas companies specific to their product • Note sensing head PPT-045 -01 48
Multiple Gas • Visual and audible alarms • Specific detector heads may be incorporated based on your hazards • This one detects: • • Oxygen content Percent LEL Carbon monoxide Hydrogen sulfide PPT-045 -01 49
Multiple Gas • Read oxygen level first to verify correct level between 19. 5 percent to 23. 5 percent or reading for LEL will be incorrect for the challenge gas/vapor PPT-045 -01 50
Multiple Gas • With pump for wand attachment – May be delay in sample reading based on length of sampling wand/hose – Monitor slowly so as to not wander into hazard zone With Pump and wand port • Without pump it will still detect, but as a diffusion detector PPT-045 -01 51
Multiple Gas • Pump brings in a measured volume of air to be tested With Pump: Drawn • More exact than hand sample is pump more exact • Without pump the measurement is Without Pump: dependent upon the Diffusion amount of ambient air coming into contact with sensing heads PPT-045 -01 52
Flame Ionization Detector • Also called FID • OVA (organic vapor analyzer) • Carbon counter • Current corresponds to positive ion collection count • Organics ionized by a hydrogen flame (not by a lamp like the PID) and counted PPT-045 -01 53
Photoionization Detector • Also called PIDs • Can be hand-held or used to monitor a fixed location • Reads most organic and some inorganic compounds • UV (Ultraviolet) lamp converts ionizing materials to electric signal (not a flame like the FID) PPT-045 -01 54
Radiological • Personal dosimeters -Self-readers -Dosimeters • Radiation field units also read: -Alpha -Beta -Gamma -Neutron PPT-045 -01 55
Radiological • Radiation causes ionization in the detecting media • Ions produced are counted electronically • Relationship established between number of ionizing events and quantity of radiation present PPT-045 -01 56
Radiological Detector Detects Ion detection tubes Gamma and X-radiation Proportional detection tubes Alpha Geiger-Mueller tubes Gamma and/or Beta Scintillation detection Alpha or Gamma PPT-045 -01 57
Other Detection Means • Samples are obtained by either: Bag sample or Swipe sample • Then subjected to sophisticated equipment (e. g. , gas chromatographs and spectrophotometers) • Each of these has its merits, but can be time-consuming PPT-045 -01 Ga s Chromatograph Spectrophotometer 58
Detector Safety • Intrinsically safe: unit won’t contribute an ignition source; per NEC (national electrical code) rated for various class, group and division uses • Class: type of flammable material • Group: types of gases or vapors • Division: location of the atmosphere PPT-045 -01 59
Detector Safety • Explosion proof: allows entrance of flammable gases but is built to contain an explosion PPT-045 -01 60
Calibration • Why calibrate? • “The calibration check is the only way to determine the meter is working properly. ” • Some calibration gases: -Methane -Pentane -Hexane • Check user’s manual Carol J. Maslansky & Steven P. Maslansky, “Air Monitoring Instrumentation, ” Van Nostrand Reinhold, 1993, page 73 PPT-045 -01 61
Calibration • Calibrate detector on a scheduled basis and before use to ensure readiness • Calibration gas can contain various PPM of selected gases for a single connection and calibration of multiple heads • Calibration assures detector will function within necessary parameters for accurate readings PPT-045 -01 62
Calibration • Dosimeter • Air check on combustible gas meter PPT-045 -01 63
Calibration Means • Multigas: replace detector heads or calibrate with gas • CGI: calibration gas • FID: electronically zeroed • PID: calibrated with gas of known PPM. Adjustments made using a span potentiometer to fine tune monitor; a new lamp may also be used PPT-045 -01 64
Match Detector to Hazard Match the detector to the hazard! • In one situation, a field team used a CGI in an acid spill atmosphere • Detector heads were “poisoned” due to contact with the acid vapor • Detector heads had to be replaced and unit overhauled PPT-045 -01 65
Detector Heads • Rated for the type of hazard • Sampling range is also important • Intrinsically safe for specific atmosphere? PPT-045 -01 66
Capabilities and Limitations • Presence of several vapors or gases in the same atmosphere may mask individual readings • Time required to read a sample • Some detectors are not meant to enter into a flammable atmosphere; they may serve as the ignition source • Ensure your detector is “intrinsically safe” • Temperature and humidity may affect readings • Altitude may affect reading • Obtain a monitor with the greatest versatility PPT-045 -01 67
Minimum Response Time • This is the time for the sample to be drawn into the equipment and for the sensor to react to the chemical if it is present. • Add time to "minimum response time" if you have attached a hose or probe extension to the inlet. • Some units indicate that 5 to 8 seconds per foot of attachment might be required before the sample is drawn into the sampling chamber of the detector. • Check manufacturer’s specifications with the unit. OSHA Fact Sheet, DSTM 9/2005 pertaining to Confined Space Entry PPT-045 -01 68
Conversion Factors • Conversion factors (also referred to as relative response): Used to correct detector readings for gases other than calibrating gas. • Some gases/vapors are either hot-burning or cold-burning gases. • This indicates how rapidly or slowly the sample releases its heat relative to the calibration gas in the meter’s sampling chamber. • The calibrating gas (calibration standard) creates a straight line on the graph relative to its heat release. PPT-045 -01 69
Conversion Factors • In sampling, the heat release of the calibrating gas will rise in a straight line across the graph. • If monitoring for the gas with which the detector was calibrated, i. e. , Methane, the reading will need no conversion adjustment. Hot Burning Gas Cold Burning Gas PPT-045 -01 70
Conversion Factor Hot-burning gases will travel more immediately up on the graph. Their conversion factor will be less than 1. 0 Cold-burning gases travel beneath the calibration gas on the graph. Their conversion factors will be greater than 1. 0 to adjust the reading Hot Burning Gas: CF <1. 0 Cold Burning Gas: CF >1. 0 PPT-045 -01 71
Conversion Factor: Example • Example: You obtain a meter reading for a gas of 15 percent LEL - the conversion factor for the gas is 2. 5 due to it being a cold-burning gas • To obtain a true reading: 2. 5 x 15 percent=37. 5 percent • This is a dangerous atmosphere that you may wish to vacate immediately • You could be entering a highly flammable area PPT-045 -01 72
Reading • Knowing the correction factor, determine the meter reading • Example: your true meter reading should not exceed 80 PPM; the gas’s correction factor is. 8 • True meter reading of 80 PPM divided by CF of. 8 = Monitor until meter reads 100 PPM PPT-045 -01 True Reading (80 PPM) Correction Meter Reading X Factor (100 PPM) (. 8) 73
Reading • Another example: The exposure limit for a gas should not exceed 125 PPM The correction factor for the gas reading is. 9 So, monitor until your meter reads 138 PPM (Divide true meter reading by correction factor to get meter reading at which to stop) PPT-045 -01 True Meter Reading (125 PPM) Correction Meter Reading X Factor (138 PPM) (. 9) 74
Field Monitoring • Determine zones • Hot, warm, cold zones • Downwind hazard areas • Conduct hazard & risk assessment PPT-045 -01 75
Hazard and Risk Assessment • • Know the hazard characteristics Match the correct detector to the hazard Understand the detectable ranges Will conversion factors apply to the target hazard? Will temperature or humidity affect readings? Is monitor intrinsically safe? Can it be calibrated? Are capabilities and limitations understood? What other safety concerns also apply? -PPE -Ventilation -Fire protection -Lock-out/tag-out PPT-045 -01 -Backup 76
Field Monitoring • Perform tasks to make area safe for monitoring • Map the release area • Select a pattern to use in the search area • Brief the monitoring team PPT-045 -01 77
Field Monitoring • Monitor the suspect location for initial readings • Continue to monitor throughout an event since conditions can change due to the possible intrusion of gases or vapors • When LEL or PPM readings are exceeded, vacate the location PPT-045 -01 78
Detector Selection • Always match the detector to the hazard • Obtain user information from the manufacturer • Determine full capabilities of monitor • Lack of preparation may put you into an analogous situation PPT-045 -01 79
Detector Selection • Never attempt to use the equipment until fully and properly trained • Understand the function of each setting • Run simulated incidents with your staff PPT-045 -01 80
Detector Selection • Ensure your staff is confident in the use • Have all questions answered completely by the vendor during the turn-over briefing and staff training. • “Know before you go” PPT-045 -01 81
Detector Selection • Maintain equipment in accordance with manufacturer’s recommendations • If in doubt regarding maintenance and calibration, consider contracting with the vendor to perform these services PPT-045 -01 82
Detection Sequence • Monitor first for oxygen content since oxygen depletion or enrichment will result in an incorrect reading in other categories • Then monitor for the LEL • Then for levels of other materials for which the detector is calibrated PPT-045 -01 83
Sewer Entry • Per 29 CFR 1910. 146 Appendix E • Entrants should be equipped with atmospheric monitoring which sounds an audible alarm, in addition to its visual readout, when: – Oxygen concentration is less than 19. 5 percent, – Flammable gas or vapor is at 10 percent or more of the lower flammable limit (LFL); or – Hydrogen sulfide or carbon monoxide is at or above 10 PPM or 35 PPM, respectively, measured as an 8 -hour timeweighted average PPT-045 -01 84
Sewer Entry • The oxygen sensor/broad -range sensor best suited for initial use in situations where actual or potential contaminants have not been identified • Substance-specific instruments may then be used when hazard is identified PPT-045 -01 85
Work a Situation • Working with one of your in-house SDSs • Select an in-house gas or flammable liquid • Identify hazard characteristics • Select a monitor • Plan your response • Create your in-house policy and procedure PPT-045 -01 86
Remember • These instruments are not toys • They are very capable within the realm for which they were designed • They also have limitations • When in doubt - check with the detector manufacturers or vendors • Do not take their use for granted. The lives of your staff may be in the balance. PPT-045 -01 87
Bibliography • Shirley A. Ness, “Air Monitoring for Toxic Exposures, ” Van Nostrand Reinhold, 1991 • Carol J. Maslansky & Steven P. Maslansky, “Air Monitoring Instrumentation, ” Van Nostrand Reinhold, 1993 • “Handbook of Compressed Gases, ” Compressed Gas Association, Inc. , 3 rd Edition, 1990 • “NIOSH Pocket Guide to Chemical Hazards, ” Department of Health and Human Services, CDC, NIOSH Publication No. 2005 -149, 2005 • OSHA Fact Sheet, DSTM 9/2005 PPT-045 -01 88
Questions PPT-045 -01 89
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