PIDs as a HazMat Response Tool
Unabridged Version 7/02
Don’t LEL sensors measure VOCs? How can we measure in ppm? PID uses in HazMat What is a PID? The Power of Correction Factors Setting PID alarms/interpreting PID output Review of specific PID applications Tips for Using and Maintaining PIDs
Training Agenda:
Most HazMat Incidents are
VOCs
Volatile Organic Compounds (VOCs)Fuels (the majority of HazMats)
Degreasers, Heat Transfer FluidsPaints, Solvents, Plastics, Resins
The Chemical Compounds that keep Industry going!
What is a VOC?
Refrigeration & Fertilizers: Ammonia (AP-201) Plastics/Fiberglass: Styrene & Methylene
Chloride Petroleum: Hydrocarbons & Benzene Automotive: Spray Booths (Paints) & Fuels Aircraft: Wing Tank Entry, Solvents &
Degreasers (AP-200) Sausages: Carbon Disulfide
Examples of Industrial PID Usage
Wool: Perchlorethylene (PERC) Printing: MEK, Toluene, IPA Environmental: Site assessments (AP-214) Pulp & Paper: Turpentine (AP-204) Heat Transfer Fluid: Therminol/DowTherm
(AP-205) Electronics: Solvents Coke Oven gases
Examples of Industrial PID Usage
Marine Chemists: Ship & Barge entry Water & Wastewater: Spill investigators Drug Enforcement: Clan Labs (AP-220) College, Hospital, R&D Labs: Spills Indoor Air Quality (IAQ) Consultants (AP-
212) Air Rifle Manufacturer Waste Receiving Stations
Examples of Industrial PID Usage
PID Sensitivity to VOCs make them an invaluable tool for HazMat Decisions:
Initial PPE Assessment Leak Detection Perimeter Establishment & Maintenance Spill Delineation Decontamination Remediation
PID Uses in HazMat
Many VOC’s are flammable and may be detected by the LEL (Lower Explosive Limit) or combustible gas sensors found in virtually every multigas monitor.
However, LEL sensors are not particularly useful in measuring toxicity because they do not have enough sensitivity.
Doesn’t LEL measure VOCs?
Wheatstone Bridge LEL Sensor
Measures change in resistance due to change in temperature of gas burning on detector
Detector
Compensator
Output
(+)4.25 V
(-) 1 k
1 k
Wheatstone Bridge is like a Stove One element has a
catalyst and one doesn’t Both elements are turned
on low The element with the
catalyst “burns” gas at a lower level and heats up
The hotter element has more resistance and the Wheatstone Bridge measures the difference in resistance between the two elements
Is the LEL Sensor Sensitive Enough?Two mechanisms can affect the
performance of Wheatstone bridge LEL sensors:
Gases burn with different heat outputs at their LEL
“Heavier” hydrocarbon vapors have difficulty diffusing into the LEL sensor and reduce its output
Active beadCompensating bead
Flame arrestor
LEL Sensor Cut-Away
Methane (CH4)Heavier Hydrocarbons
Heavier Hydrocarbons Rejected by the Flame Arrestor
Gas/Vapor LEL (%vol) Sensitivity (%)Acetone 2.2 45Diesel 0.8 30Gasoline 1.4 45Methane 5.0 100MEK 1.8 38Propane 2.0 53Toluene 1.2 40
LEL Sensor sensitivity varies with chemical
LEL Sensor Relative Sensitivity
LEL Sensor Cal Gases Pentane and Propane are often used as LEL
sensor calibration gases because their response is closer to most common flammable vapors
LEL sensors fail to “see” Methane first, so you could calibrate properly on Pentane or Propane yet not “see” Methane at all
The safest calibration is to calibrate with Methane gas and then set the scale to Pentane or Propane
Surrogate or simulant cal.
Using PIDs for LEL Multiply %volume by 10,000 to get ppm. LEL Gasoline is 1.2% by volume or 12,000
ppm 10% of LEL Gasoline is 1200 ppm
PIDs often are a better measurement tool for 10% of LEL for fuels and
chemicals
Using PIDs for 10% of LEL
ChemicalName
LEL(%vol)
LEL inPPM
10% ofLEL inPPM
10% ofLELRU10.6
Acetone 2.5 25000 2500 2273Gasoline 1.4 14000 1400 1647MEK 1.4 14000 1400 1628Styrene 0.9 9000 900 2250THF 2 20000 2000 1111Toluene 1.1 11000 1100 2200Xylene 1.1 11000 1100 2558
Wingtank LEL Entrants can see and smell jet fuel but
their LEL meters read nothing LEL sensor just can’t see jet fuel Aircraft maintenance exposes sensor to
poisoning silicone compounds PIDs are used to make LEL decision
Wingtank LEL
Clues
Tubes
Clues: wingtank containing jet fuel residue
LEL: little or no reading PID: 800 ppm in jet fuel
units is 10% of LEL
=800 ppm is 10% of LEL
PID
Toxic Sensors
LEL
Pulp & Paper Turpentine LEL Operator using a properly calibrated monitor
did not measure flammable levels of turpentine but was severely burned in a turpentine flash during hot work
LEL sensor just can’t see turpentine Sulfur compounds in Pulp & Paper act as
chronic poisons to LEL sensor that at its best can barely see turpentine
Monitors now have LEL and PID
Pulp & Paper Turpentine LEL
Clues
Tubes
Clues: turpentine recovery unit
Toxic Sensor: low reading on H2S sensor common in a pulp plant
LEL: no reading PID: 800 ppm in
turpentine units or 10% of LEL=800 ppm is
10% of LEL
PID
Toxic Sensors
LEL
Using PIDs for 10% of LEL
1000 ppm in Isobutylene units is a conservative
measure of 10% of LEL for many common VOCs
LEL Measures EXPLOSIVITY not TOXICITY! Many VOCs are toxic well below the
sensitivity of an LEL sensor Xylene = 100 ppm
Using LEL to measure for Toxicity is like using a yardstick to measure the thickness of a sheet of paper!
A PID can measure TOXICITY!
Explosivity Vs Toxicity
LEL Compared to PIDLEL gets you home tonight
PID lets you enjoy retirement! LEL is more for Acute toxicity which will
get you immediately (IDLH) PID is more for Chronic Toxicity which will
get you over a longer period of time (TWA)
Toxicity = Concentration x Exposure Period
We now need to measure in PPM!
How can we measure in PPM? Colorimetric Tubes Metal Oxide Sensor (MOS) Portable GC/MS Flame Ionization Detectors (FID) Photo Ionization Detector (PID)
Colorimetric Tubes measure in PPM+Proven technology− “Snap Shots” like a “Polaroid” camera, non-
continuous, no alarms− “Spot Checks” result in sampling error−Respond in minutes rather than seconds−15-25% accuracy Piston/Bellows style−Readings subject to interpretation−Generate Glass splinters & chemical waste−Tubes expire & large stock is expensive
MOS Sensors Measure in PPM+Faster response than tubes & continuous+Affordable (“Poor Man’s PID”)−Detection limits in 10s of ppm at best−Non-linear output limits accuracy (its like a rubber ruler)−Still slower to respond than PID or FID−Sensitive to Temperature and Humidity leading to false
alarms −Can be poisoned & ruined by over-ranging−Non-specific
Portable GC/MS measures in PPM+Very Accurate +Very Specific− “Snap Shots” like a “Polaroid” camera, non-
continuous, no alarms− “Spot Checks” result in sampling error−Respond in minutes rather than seconds−Very complicated−Very heavy and bulky−Prohibitively expensive
FIDs Measure in PPM+Fast response+Very Accurate −Complicated−Heavy and bulky−Expensive−Non-specific
The difference between FID and PID is like the difference between a meterstick and a
yardstick!
PIDs Measure in PPM+Fastest response+Very Accurate (the “heart of a GC”). Entry
decisions can be made directly based on PPM with confidence.
+Optical Technology not affected by contaminants
+Non-specific
“Traditional” PIDs Were Just One Step Away from the Lab!
High cost of purchase & maintenance Lack of durability Bulky size & heavy weight Sensitivity to Humidity and RFI
Design breakthroughs solve these problems so that PIDs can be used for
HazMat!
Why aren’t PIDs More Common?
Initial PPE Assessment Leak Detection Perimeter Establishment & Maintenance Spill Delineation Decontamination Remediation
PID Uses in HazMat
Some “Incidents” may not be an “Incident” at all and many not require any PPE (Personal Protective Equipment)
Some non-incidents are really “INCIDENTS” and require substantial PPE
PIDs are an excellent AID in this decision making process
Initial PPE Assessment with a PID
Initial PPE Assessment with a PID
Benzene (PEL = 1 ppm) Ambient conditions: 95oF (35oC),
95% Humidity
How do you dress out?
Pool of Liquid under Benzene Tank Car
Initial PPE Assessment with a PID
PID is very sensitive to Benzene Level A is unnecessary if no Benzene Level A represents a Heat Stress Risk Car contents at 65oF (18oC) “Leak” really condensation
Leak Detection with a PID
PID allows you to “see” concentrations As concentration increases you are
closer to the source
“See” the Concentration Gradient
10,000 PPM Perchlorethylene (PERC)
0 PPM PERC
Perimeter Monitoring with a PIDSet based upon conditions by
experienced HazMat Techs Physical Characteristics of Chemical Toxicity of Gas or Vapor Temperature Wind Direction
Changes in Conditions are often Missed by Untrained Perimeter Workers
Perimeter Monitoring with a PIDGasoline Tank Truck Rollover
8:00 AM45oF (7oC)No wind
TWA = 100 ppm
Perimeter Monitoring with a PIDGasoline Tank Truck Rollover
8:00 AM45oF (7oC)No wind
10,000 PPM Gas
50 PPM (1/2 of TWA)
Perimeter = 100 feet
Perimeter Monitoring with a PIDGasoline Tank Truck Rollover
11:00 AM75oF (24oC)10 mph wind
10,000 PPM Gas
600 PPM
Perimeter now should be 300 feet Perimeter worker overexposed
Perimeter Monitoring with a PIDDatalogging as a Tool
Document Perimeter Worker Exposures
Provide Evidence to Justify Evacuations
PIDs for Spill DelineationMany Liquids can be present in a
HazMat Incident Water Fuels Engine Fluids Foam
PIDs for Spill DelineationIt’s Hard to tell pavement “wet” with water from
pavement “wet” with diesel just by looking
PIDs for Spill Delineation
Limited Absorbent can be Efficiently used only on the Diesel Spill
PIDs can help separate the “Water” from the “Oil”
PIDs for Decon
Is Worker Contaminated? Is Decon Complete? Can we reuse suit? Is my turn-out contaminated
with Fuel Products? This same sensitivity to
hydrocarbons makes PIDs ideally suited for arson investigation
(Ref AP-207)
PIDs can help answer these questions:
Using a PID for Remediation
Using a PID for Remediation
Hazardous Materials can evade the best attempts at containment:
Is Soil Contaminated enough to require further clean-up?
Is Water Contaminated enough to require further clean-up?
Using a PID for Remediation
Put contaminated soil or water in a container
Cover the container and bring it up to room temperature (~15 min)
Put PID probe into container and sample
Generally <100 ppm is good Ref AP-214
How to do a Headspace Sample:
What is a PID? PID = Photo-Ionization Detector Detects VOCs (volatile organic compounds)
and Toxic gases from <10 ppb to as high as 10,000 ppm
Over 90% of HazMat incidents are fuel product related and are easily measured with a PID
A PID is a very sensitive broad spectrum monitor, like a “low-level LEL”
100.0 ppm
Gas enters the instrument
It passes bythe UV lamp
It is now “ionized” Charged gas ions
flow to charged plates in the sensor and
current is produced
Current is measured and concentration is
displayed on the meter.
++--
++
--
++
--++
--++--
Gas “Reforms” and exits the
instrument intact
How does a PID work?An optical system using
Ultraviolet lamp to breakdown vapors and gases for
measurement
Organics: Compounds Containing Carbon (C) Aromatics - compounds containing a benzene ring
BETX: benzene, ethyl benzene, toluene, xylene Ketones & Aldehydes - compounds with a C=O bond
acetone, MEK, acetaldehyde Amines & Amides - Carbon compounds containing Nitrogen
diethyl amine Chlorinated hydrocarbons - trichloroethylene (TCE) Sulfur compounds – mercaptans, carbon disulfide Unsaturated hydrocarbons - C=C & C C compounds
butadiene, isobutylene Alcohol’s
ethanol Saturated hydrocarbons
butane, octane Inorganics: Compounds without Carbon
Ammonia Semiconductor gases: Arsine
What does a PID Measure?
What PIDs Do Not Measure Radiation Air
N2
O2
CO2
H2O Toxics
CO HCN SO2
Natural gas Methane CH4
Ethane C2H6
Acids HCl HF HNO3
Others Freons Ozone O3
Ionization Potential IP determines if the PID can “see” the gas If the IP of the gas is less than the eV output of
the lamp the PID can “see” it Ionization Potential (IP) does not correlate with
the Correction Factor Ionization Potentials are found in RAE
handouts (TN-106), NIOSH Pocket Guide and many chemical texts.
What does a PID Measure?
If the “wattage” of the gas or vapor is less than the
“wattage” of the PID lamp then the PID can “see” the gas or vapor!
8
9
10
11
12
13
14
15
8.4
9.24 9.549.99 10.1 10.5
10.6611.3211.47
12.1
14.01
Some Ionization Potentials (IPs) for Common ChemicalsSome Ionization Potentials (IPs) for Common Chemicals
Benzene
MEK
Vinyl Chloride
IPA
Ethylene
Acetic A
cid
Methylene
chloride
Carbon Tet.
Carbon
Monoxide
Styrene
Oxygen
Ionization Potential
(eV)
11.7 eV Lamp
10.6 eV Lamp
Not Ionizable
What does a PID Measure?
9.8 eV Lamp
9.8 & 10.6 provide more specificity 10.6 lasts 24-36 months 10.6 provides best resolution 10.6 costs less ($195) 11.7 is required for high energy compounds like
Methylene Chloride 11.7 crystal absorbs water and degrades 11.7 lasts about 2-3 months 11.7 costs more ($345 in ampule)
Why not always use 11.7 eV Lamps?
Selectivity Vs Sensitivity PID is very sensitive and accurate PID is not very selective
Selectivity Vs Sensitivity PID is very sensitive and accurate PID is not very selective
Ruler cannot differentiate between yellow and
white paper
Selectivity Vs Sensitivity PID is very sensitive and accurate PID is not very selective
PID can’t differentiate between ammonia &
xylene
Selectivity Vs SensitivityUse your head for Selectivity and the PID
for Sensitivity PID is sensitive to chemicals not specific Correction Factors set correct PID scale PID should stay on Isobutylene (Calibration
gas) until unknown is identified
A PID is a Gas Chromatograph where the column is between your ears!
Selectivity Vs Sensitivity
No Correction Factor is used until compound is identified
Identify then Quantify!
Correction Factors are the key to unlocking the power
of a PID for Assessing Varying Mixtures and
Unknown Environments
What is a Correction Factor?
Correction Factor (CF) is a measure of the sensitivity of the PID to a specific gas
CFs are scaling factors, they do not make a PID specific to a chemical, they only correct the scale to that chemical.
Correction Factors allow calibration on cheap, non-toxic “surrogate” gas.
Ref: RAE handout TN-106
What is a Correction Factor?
Low CF = high PID sensitivity to a gas If the chemical is bad for you then the PID
needs to be sensitive to it If Exposure limit is < 10 ppm, CF < 1
If the chemical isn’t too bad then the PID doesn’t need to be as sensitive to it
If Exposure limit is > 10 ppm, CF < 10 Use PIDs for gross leak detectors when CF
> 10
CF’s measure sensitivity
Toluene CF with 10.6eV lamp is 0.5 so PID is very sensitive to Toluene
If PID reads 100 ppm of isobutylene units in a Toluene atmosphere
Then the actual concentration is 50 ppm Toluene units
0.5CF x 100 ppmiso= 50 ppmtoluene
CF Example: Toluene
Ammonia CF with 10.6eV lamp is 9.7 so PID is less sensitive to Ammonia
If PID reads 100 ppm of isobutylene units in an Ammonia atmosphere
Then the actual concentration is 970 ppm Ammonia units
9.7CF x 100 ppmiso= 970 ppmammonia
CF Example: Ammonia
Making a Decision with a PID
Two sensitivities must be understood to make a decision with a PID
Human Sensitivity: as defined by AGCIH, NIOSH, OSHA or corporate exposure limits
PID Sensitivity: as defined through testing by the manufacturer of your PID (RAE CF)
ONLY USE A CORRECTION FACTOR FROM THE MANUFACTURER OF YOUR PID!
Making a Decision with a PID
PID sensitivity + Human Sensitivity = Decision
orCF + Exposure Limit = Decision
Reference AP-221
Making a Decision with a PID
Three scenarios on how to make a decision with a PID
Single Gas/Vapor Gas/Vapor mixture with constant make-up Gas/Vapor mixture with varying make-up
Single Chemicals are easy Identify the chemical Set the PID Correction Factor to that chemical Find the Exposure Limit(s) for the chemical Set the PID alarms according to the exposure
limits
The “Real World” is rarely this easy. Most applications are a “Witches Brew” of
VOCs
PID Alarms: Single Chemical
Paint: 15% Styrene and 85% XyleneELmix = 1/(0.15/50 + 0.85/100) = 87 ppm
Where: 0.15 is 15% styrene 50 is the 50 ppm exposure limit for styrene 0.85 is 85% xylene 100 is the 100 ppm exposure limit for xylene Ref: TN-106 & NIOSH Pocket guide, AP-211 & AP-
221
PID Alarms: Constant Mixtures
Paint: 15% Styrene and 85% XyleneCFmix = 1/(0.15/0.4 + 0.85/.6) = 0.56
Where: 0.15 is 15% styrene 0.4 is the CF styrene 0.85 is 85% xylene 0.6 is the CF for xylene Ref: TN-106, AP-211 & AP-221
PID Alarms: Constant Mixtures
Paint: 15% Styrene and 85% Xylene In the sealed up living room I got a reading
of 120iso on the PID in Isobutylene units Multiplying it by the correction factor of
0.56mix my real reading on the mixture was 67.2mix ppm
This is under the calculated exposure limit of 87mix ppm for the mixture
PID Alarms: Constant Mixtures
Constant Mixture Shortcut #1Paint: 15% Styrene and 85% Xylene
Lets consider it to be just Xylene In the sealed up living room I got a reading of
120 on the PID in Isobutylene units Multiplying it by Xylene CF of 0.59 my real
reading as Xylene is 70.8 ppm This is under the Xylene exposure of 100 ppm
PID Alarms: Constant Mixtures
Constant Mixture Shortcut #2 Find the average make-up of the mixture Determine the most toxic VOC Base setpoints on the most toxic VOC
WARNING: Shortcuts only provide a quick guideline!
PID Alarms: Constant Mixtures
Gasoline “Gas” contains as much as 1% Benzene Benzene is carcinogenic (PEL = 1 PPM) 100 PPM of Gasoline contains as much as 1
PPM Benzene Set High Alarm at 100 PPM Gas < 1.0 PPM
Benzene Set Low Alarm at 50 PPM Gas < 0.5 PPM
Benzene
PID Alarms: Constant Mixtures
The Controlling Compound Every mixture has a compound that is the
most toxic and “controls” the setpoint for the whole mixture
Determine that chemical and you can determine a conservative mixture setpoint
If we are safe for the “worst” chemical we will be safe for all chemicals
PID Alarms: Varying Mixtures
Ethanol “appears” to be the safest compound Toluene “appears” to be the most toxic This table only provides half of the decision
making equation Might as well compare 1000 apples to 100
oranges
PID Alarms: Varying Mixtures ChemicalName
10.6eV CF Exposure LimitChemical
Ethanol 12 1000Toluene 0.50 100Acetone 1.1 750
People are accustomed to making decisions solely on human sensitivity
Users of meters also need to take into account meter sensitivity
It is necessary to simultaneously interpret both human and meter sensitivity
PID Alarms: Varying Mixtures
Set the PID for the compound with the lowest Exposure Limit (EL) in equivalent units and you are safe for all of the chemicals in the mixture
Divide the EL in chemical units by CF to get the EL in isobutylene
ELIsobutylene = ELchemical CFchemical
PID Alarms: Varying Mixtures
ChemicalName
10.6eVCF
ELChemical
ELIsobutylene
Ethanol 12 1000 83.33Toluene 0.50 100 200.00Acetone 1.1 750 681.82
Now one can compare “Apples to Apples” Its lower sensitivity on the PID makes Ethanol
the “controlling compound” when the Exposure Limits are expressed in equivalent “Isobutylene Units”
PID Alarms: Varying Mixtures
Setting the PID to 83 ppm alarm in Isobutylene units protects from all three chemicals no matter what their ratio
IMPORTANT: in the rest of this discussion, “Exposure Limit in Isobutylene” will be called or ELiso. ELiso is a calculation that involves a vendor specific Correction Factor (CF). Similar calculations can be done for any PID brand that has a published CF list.
PID Alarms: Varying Mixtures
PID Alarms: ELiso & Unknowns ELiso thresholds are a tool to help characterize
unknown environments. The lower the reading in isobutylene units on
your PID the less risk. If the reading on your PID is below the ELiso
for a chemical there isn’t a threat.
ChemicalName
10.6eVCF
ELChemical
ELIsobutylene
PID in Iso 45Styrene 0.4 100 250Toluene 0.50 100 200.00Cumene .54 50 92
For example, if the PID reads 45iso ppm in an area with Toluene (ELiso =400), Styrene (ELiso =250) and Cumene (ELiso =92) vapors we are safe because the ELiso for all three of these chemicals is well above 45 ppm.
PID Alarms: Varying Mixtures
PID Alarms: ELiso & UnknownsA RAE PID with a 10.6eV lamp set to the following alarms and not beeping provides
protection from: 44 chemicals at a 100 ppm alarm, includes solvents like Xylene,
Toluene, MEK, Acetone 65 chemicals at a 50 ppm alarm, from Cyclohexanone to
Acetone. 81 chemicals at a 25 ppm alarm, from Diethylamine to Acetone. 105 chemicals at a 10 ppm alarm, from Toluidine to Acetone. 140 chemicals at a 1 ppm alarm, from Diethylenetriamine to
Acetone
PID Alarms: ELiso & Unknowns Setting an alarm to 1 ppm provides the highest
protection, but it also causes the most alarms. An alarm point of 1 ppm would be similar to
always wearing a Level A suit! A 50 ppm ELiso alarm is appropriate for going
to respiratory protection in a fuel tanker roll-over because an ELiso alarm of 50 is very conservative for all hydrocarbon fuels.
PID Alarms: the 50/50 Rule
Acetone Cyclohexane Diesel Fuel Ethyl alcohol Ethylbenzene Gasoline Heptane, n- Hexane, n-
Stoddard Solvent Styrene Tetrahydrofuran Toluene Trichloroethylene Xylene
When Measuring in Isobutylene Units and set to 50 ppm RAE PIDs
will protect from over 50 of the most common Chemicals:
IPA Jet Fuel MEK MIBK MPK Nonane Octane, n- Pentane
PID Alarms: ELiso & Unknowns
Of course, if there are known or suspected chemicals of higher risk a lower alarm might be called for.
In a potential terrorist chemical agent attack, a ELiso of 1.00 ppm might be more appropriate
ChemicalName
10.6eVCF
LCT50 ELIsobutylene
PID in Iso 1Mustard 0.6 231 385Tabun 0.8 20 25Sarin 3.0 12 4.0
PID Alarms: ELiso & Unknowns ELiso are only one gauge of the threat level
in any circumstance. The PID user must use all of the clues
present to reach a decision.
PIDs can be an important part of any gaseous risk assessment and
should be used with other clues present:
Response from other types of meters Response from colorimetric tubes Physical clues Worker/Victim symptoms
Integrating Gas Detection Techniques
The Gas Monitoring Pyramid is a graphic depiction of how to
integrate various gas monitoring techniques
Integrating Gas Detection Techniques
TubesSingle Gas: CO/O2/LEL
Multigas CSEBroadband: MOS
Selective: IMSSelective: GC/MSSelective: Tubes
Broadband: PID/FID
Gas Monitoring
Pyramid
Selectivity Increases as you move up the Pyramid
The AnswerThe Answer
Integrating Gas Detection Techniques
TubesSingle Gas: CO/O2/LEL
Multigas CSEBroadband: MOS
Selective: IMSSelective: GC/MSSelective: Tubes
Broadband: PID/FID
PID + Tubes Approximates the selectivity of GC/MS w/o the cost
Gas Monitoring
Pyramid
The AnswerThe Answer
Integrating Gas Detection Techniques
Integrating Gas Detection Techniques
Clues
LEL Tubes
Each circle represents the range of chemicals seen by a sensor
By overlaying multiple detection techniques we can zoom in on the solution
Use multiple techniques until you feel comfortable with the solution=The Real
Answer
PIDToxic
Sensors
In food warehouse maintenance room had 80 ppm CO indicated
Assumed that they used propane forklifts (common source of CO) but found that they used battery powered forklifts
The maintenance room was located with in the battery charging area.
Lead acid batteries generate hydrogen (H2) when charging
Food Warehouse
Food Warehouse 80 ppm indicated CO translates to 200 ppm
H2 or about 0.5% of LEL H2
No LEL reading, H2 LEL is 4% (40,000 ppm), 1% of LEL H2 is just 400 ppm
Checked with CO colorimetric tube and registered no CO reading
Concluded that CO reading on monitor was due to H2 cross-sensitivity
Food Warehouse: CO Cross-Sensitivity
Clues
Tubes
Clues: Warehouse w/ battery powered forklifts
Toxic Sensor: 80 ppm reading on CO if H2 it’s approximately 200 ppm
LEL: no reading on LEL PID: no reading on PID Tubes: no reading on CO
tube=Probably Hydrogen gas from forklift batteries
PID
Toxic Sensors
LEL
CO sensor indicated 35-45 ppm in printed circuit board plant with styrene, xylene, acetone and other aromatics and ketones
Jumped to false conclusion that CO sensor was bad or responding to hydrocarbons
Fresh aired monitor outside plant and still had high CO in plant
Printed Circuit Board Plant
Calibrated with CO gas and still had high CO in plant
Checked with CO colorimetric tube and registered 50 ppm CO reading
Investigated plant and found shrink-wrap machine pumping out 150 ppm CO in worker breathing zone
Printed Circuit Board Plant
Printed Circuit Board Plant
Clues
Tubes
Clues: Printed circuit board plant
Toxic Sensor: 35-45 ppm reading on CO
LEL: no reading on LEL PID: no reading on PID Tubes: 50 ppm reading on
CO tube=CO from shrink wrap machine
PID
Toxic Sensors
LEL
Portable CO monitor showed no CO CO Colorimetric tube found no CO PID read 100 ppm Investigation revealed spray painting had
taken place Home CO detectors use less filtered CO
sensors that can respond readily to hydrocarbons
Home CO Detector
Home CO Detector
Clues
Tubes
Clues: Household CO call, smells like paint solvent
Toxic Sensor: 0 ppm reading on CO
LEL: no reading on LEL PID: 100 ppm reading on
PID Tubes: no reading on CO
tube=spray paint set off home CO detector
PID
Toxic Sensors
LEL
Oil Refinery Remediation H2S Datalogging meter showed H2S of straight 199 ppm
indicating they had maxed out the H2S circuit on the meter (meter & sensor only rated to 100 ppm H2S)
This data is questionable but we certainly have more than 100 ppm and may have more than 200 ppm H2S
PID data from the same meter showed 240 ppm in Isobutylene units
No LEL reading and H2S is a LEL inhibitor
Using PID correction factor for H2S of 3.3, the concentration if it were just H2S is 792
PID measures total VOCs including H2S so part of the signal could be VOCs
We can be pretty sure that we had a lot of H2S and it could be 100-790 ppm (IDLH =100 ppm)
Further testing via sampling and lab testing was recommended
H2S colorimetric tubes could also be used
Oil Refinery Remediation H2S
Oil Refinery Remediation H2S
Clues
Tubes
Clues: Refinery clean-up with strong H2S smell
Toxic Sensor: 199 ppm reading on H2S sensor
LEL: no reading (LEL = 4% or 40,000 ppm)
PID: 240 ppm in iso units or 792 in H2S units
Tubes: not used but would have been helpful=a lot of H2S is
present
PID
Toxic Sensors
LEL
Homeowner “smells” natural gas after gas company work
Natural gas is methane and other short-chain saturated compounds
Natural gas doesn’t smell but Mercaptan odorant is added for safety purposes
Mercaptans are “sticky” and can remain on clothes and fabrics even after all work is done and the atmosphere is safe
Home Natural Gas Leak
Home Natural Gas Leak
Smell is most likely leftover from gas company work, but good idea to have gas company recheck their work
Methane %Volume ppm ppb100% LEL 5 50000 5000000010% LEL 0.5 5000 50000001% LEL 0.05 500 5000000.1% LEL 0.005 50 50000
OdorThresholdMethylMercaptan
0.0000001 0.0001 0.1
Olfactory threshold for Methyl Mercaptan is well below the detection capability of even the PID
Home Natural Gas Leak Clues: homeowner
compliants Toxic Sensor: no
readings LEL: no reading PID: no reading Tubes: no reading on
mercaptans tube=odorants are very powerful and purvasive
Clues
Tubes
PID
Toxic Sensors
LEL
Review of Specific PID Applications AP-201: Measuring Ammonia with PIDs AP-207: PIDs as an Arson Tool AP-212: PIDs for Indoor Air Quality (IAQ) AP-216: Using PIDs for Terrorist Chemical
Attacks AP-219: Using PIDs for 10% of LEL Decisions AP-220: Using PIDs in Clan Lab Investigations
PIDs to Measure Ammonia Decision to go from Respiratory protection to
Level A is typically between 250-1500 ppm Ammonia sensors “burn-out” at 200-300 ppm
so responders go to Level A early Ammonia sensors are for “nuisance” levels in
range of 0-50 ppm Use PIDs when you can “see” ammonia and
levels are over 100 ppm Ref. AP-201
PIDs for Arson Investigation Hydrocarbon liquids are common accelerants The PID provides excellent sensitivity to hydrocarbons
even after burn off PIDs aren’t specific to accelerants PIDs can help to confirm that a suspicious burn pattern is
the best place to sample for the highest levels of accelerant PIDs are less expensive than dogs PIDs don’t suffer from olfactory fatigue and are not
distractible Ref. AP-207
PIDs for IAQVOCs are one of the top IAQ Contaminants Biological Agents (mold, dustmites, etc.) Carbon Monoxide Formaldehyde Second Hand Smoke VOCs
PIDs are one of the only direct measuring meters for IAQ
PIDs for IAQ
PIDs Solve Paint Odor Problem Normal IAQ is 100-500 PPB in isobutylene
units Above 500 ppb look for problems Use PID like a “Geiger Counter” to find source Chemical formulas on most paint and glue
containers allow you to quickly identify the chemicals
PIDs for IAQ
PIDs Solve Paint Odor Problem NIOSH Pocket Guide helps you to quickly find
the safe levels for chemicals PID correction factors let you set the scale of the
PID to the chemical of interest so that the reading is accurate
Using the PID scaled with the right correction factor you can quickly and accurately measure the level of the paint fumes
PIDs for IAQ
PIDs Solve Paint Odor Problem If fumes are at safe levels, the PID can help prove
that it is safe for the occupants to stay in the building
It might be necessary to explain the difference between odor threshold and toxicity
For example, the odor threshold for toluene is 0.16-37 ppm while the 8 hour NIOSH TWA is 100 ppm.
PIDs for IAQ
PIDs Solve Paint Odor Problem In the politically charged situations posed by
many IAQ complaints, a fast measurement tool like the PID is invaluable. It can save time, money and headaches
(Ref AP-212)
Guidelines for Using PIDs for IAQ
In the politically charged situations posed by many IAQ complaints, a fast measurement
tool like the PID is invaluable. <100 ppb Isobutylene: normal outdoors 100-400 ppb Isobutylene: normal indoors 500-1000 ppb Isobutylene: threshold for
potential IAQ complaintsIt can save time, money and headaches
PIDs for Terrorist Chemical Attacks Initially WMD programs were focused on
Chemical Warfare Agents (CWAs) Terrorists don’t have to use military CWAs There is better access to Toxic Industrial
Chemicals (TICs) and there are many more TICs available
CWA Specific Detectors (IMS, SAW) can’t measure TICs and can be fooled by common chemicals
PIDs for Terrorist Chemical Attacks
Just two words separate a Terrorist chemical attack from a HazMat Incident
If the “INTENT” is to create “FEAR”, then it’s terrorism
PIDs are one of the best broadband chemical detectors and they can be very useful in a risk based WMD response
Ref. AP-216
PIDs for Terrorist Chemical Attacks
IMS
SAW Tubes
PID
Each circle represents the range of chemicals seen by a sensor
By overlaying multiple detection techniques we can provide specificity to CWA
CWA specific sensors cannot measure TICs=CWA
=TIC
Clan Labs typically are contaminated Continuous measurement reduces responder risk Wheatstone bridge sensors have difficulty in the clan
lab environmentHigh Flashpoint chemicalsCommon clan lab chemical poison LEL
Recommended Clan Lab alarms:High: 250 ppm for 10% of LELLow: 5 ppm for respiratory
Ref: AP-220
Using PIDs in Clan Lab Investigations
Tips for Using and Maintaining PIDs
Never Use Tygon tubing! Absorbs chemicals like a “sponge” Reduces ppm readout when
chemicals exist Causes “false positives” when
chemicals don’t exist
Always use Teflon or similar non-reactive tubing Will not absorb chemicals but might
get coated Clean with anhydrous methanol if it
gets dirty
PID: Tubing
How Humidity Affects PIDs
The closer to the headlights the easier it is to see something through fog.
By reducing the distance the UV light travels in a PID the affects of humidity are drastically reduced
Short Lightpath
Long Lightpath
PID: Maintenance PID Drift is Due to Poor Sampling Technique
Aspirating liquids & vapors into sample probe Aspirating dirt samples into sample probe Hot liquids and vapors condensing in probe & sensor Touching contaminated surfaces with probes
Clean PID Lamp & Sensor When display creeps upwards after good zero When PID responds to moisture When movement of PID results in response on display
PID: Maintenance How to Clean PID Sensor
Always clean sample probe and replace or clean filters FIRST! If PID holds a stable zero after this step then further cleaning may not be necessary
Use anhydrous methanol (Lamp cleaning solution) Clean lamp face with lens tissue Clean sensor by immersion in cleaning solution (an
ultrasonic cleaner will speed cleaning)
Drying the PID Let air dry overnight Warm air (not hot) will speed drying
A PID is like a Magnifying GlassA Magnifying glass lets a detective
see fingerprints; a PID lets us “see” VOCs
Identify then Quantify!
Benzene
AmmoniaCarbon Disulfide
Styrene
XyleneJet FuelPERC
Questions?
RAE PID Products
RAE PIDs: ToxiRAE The ToxiRAE is a Personal Protection PID Affordable personal monitor for
Initial PPE Assessment Perimeter Establishment and Maintenance
Use 4 to for North, South, East and West Perimeter
PID & multigas monitor For both Protection and Detection Our most versatile monitor
RAE PIDs: MultiRAE
Initial PPE AssessmentLeak DetectionPerimeter
Establishment & Maintenance
Spill DelineationDecontaminationRemediation
0-10,000 PPM w/excellent linearity
Strong pump Superior PID sensor resists
moisture & dirt Quick Lamp & Sensor Access
w/o tools Rugged rubber boot standard NiMH Drop-in battery w/backup
alkaline pack
RAE PIDs: MiniRAE 2000
Continuous detection to 1 ppb! 0-9999 PPB or 0-200 PPM Can detect VOCs at or below
the olfactory threshold for IAQ. Measures highly toxic
compounds with low vapor pressures like chemical agents and isocyanates (TDI & MDI)
RAE PIDs: ppbRAE
Rugged, one-to-five sensor monitoring system
“ProRAE Remote” software simultaneously controls and displays readings for up to 16 remote units up to 2 miles downrange
Runs up to 36 hours on Li-Ion
RAE PIDs: AreaRAE
Local Area Monitoring
( ISM )