Podcast
Questions and Answers
Which feature is NOT considered when evaluating detection and monitoring equipment?
What does the detection limit refer to in monitoring equipment?
Which statement best describes selectivity in detection and monitoring instruments?
Which aspect is crucial for ensuring the usability of equipment in hazardous environments?
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What is indicated by the saturation limit concerning detection instruments?
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What is the primary purpose of ongoing monitoring in emergency response?
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What does instrument response time depend upon?
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Which of the following statements about monitoring equipment is incorrect?
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What might occur as a result of interference in instrumentation?
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What factor can affect the accuracy of instrument readings?
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What action should be considered when the action level is reached for known chemicals?
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Which factor is NOT a consideration when conducting individual monitoring?
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Which of the following describes the function of amplification in a detection device?
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What does reliability in a measuring instrument primarily ensure?
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What is the main difference between individual monitoring and area monitoring?
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When should more conservative action levels be implemented?
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What is the main purpose of a bump test in calibration?
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Which of the following best represents the concept of relative response or correction factors in instruments?
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Which statement is true regarding vapor density during monitoring?
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What factors can influence the time it takes for an instrument to provide a reading after drawing in an air sample?
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What is a possible outcome of high LEL action levels for known chemicals?
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What is the primary purpose of filters in instrumentation?
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What does the term 'specificity' refer to in the context of instrument measurement?
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What is a common feature of passive monitoring instruments?
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What factors must a technician consider when selecting sampling locations during an outdoor monitoring operation?
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What is the primary objective of area monitoring in hazardous situations?
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Which piece of equipment is NOT typically used to measure air concentrations at a hazardous scene?
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When working in confined spaces, which characteristic is NOT accurate?
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In the context of cargo container monitoring, what should technicians be cautious about?
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What is the first step that technicians must take before sending samples to a laboratory?
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Which factor is critical when conducting field screening for explosives?
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What should technicians look for as indicators of potential shock-sensitive explosives during field screenings?
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What method is used to test for the flammability of materials in the field screening process?
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In the sampling plan, which step must be taken before entering the exclusion zone?
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What role does the assistant play during the sampling process?
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Which type of detector is specifically used to measure volatility in organic compounds?
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What is necessary for physical evidence to be admissible in court?
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Which chemical is used to test for oxidizers in field sampling?
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During field screening, which type of radiation is not typically tested?
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What is a critical aspect of preparing samples according to the sampling plan?
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Study Notes
Detection and Monitoring
- Detection and monitoring instruments aid in emergency response to chemical releases by providing information for safe and risk-based actions.
- Monitoring is a continuous process using a combination of instruments, as no single instrument can identify or quantify all compounds.
- Detection and monitoring equipment helps to estimate concentrations of known products, identify unknown products, identify hazards, evaluate health and safety effects, and assess exposures.
Evaluating Detection and Monitoring Features
- Safety and user-friendliness are important considerations for field use.
- Key evaluation aspects include:
- Portability and durability
- Cost (initial, maintenance, calibration, sensor replacement, updates, training)
- Ease of operation (especially while wearing PPE)
- Usability in hazardous environments (explosion-proof, intrinsically safe, purged)
Technology Considerations
- Instruments must read, interpret, and communicate data accurately in hazardous materials situations.
- Factors to consider:
- Instrument response time:
- Time to generate data (seconds to minutes)
- Influenced by test type, wait time, sensitivity, and interference.
- Sensitivity:
- Accuracy of measuring concentration changes
- Detection limit (smallest quantity identified within a confidence level)
- Saturation limit (concentration where adding more solute does not increase dissolved solute levels)
- Selectivity:
- Ability to detect and measure specific chemicals or groups of similar chemicals
- Depends on interfering compounds
- Interference affects accuracy
- Specificity:
- Comparison of antigen and antibody relationship
- Operating range:
- Accurate concentration measure by the instrument
- Amplification:
- Increases small electronic signals from the detector to the readout, without affecting sensitivity
- Accuracy:
- Relationship between actual value and instrument reading
- Reliability:
- Consistently accurate readings
- Instrument response time:
Instrument Response
- The elapsed time between sample intake and analysis provided to the user.
- Time depends on test type, dead time for analysis, and instrument sensitivity
- Some instruments are passive, relying on air movements for sampling.
- Others use pumps and draw tubes.
Calibration
- Standardizing a measuring instrument before and after each use, and at regular intervals.
- Checked against calibration gas.
- Bump Test (Calibration Test): ensures alerts function correctly at recommended test levels for hazard detection, comparing to the actual gas quantity.
- Performed before entering the hazard area, not for resetting calibration but to determine correct settings.
Relative Response/Correction Factors
- Each instrument responds to vapors/gases as if detecting its calibration gas, potentially resulting in readings higher or lower than the actual concentration.
- Correction factors/relative response curves convert instrument readings to true concentrations if the vapor/gas can be identified.
Cross-Sensitivities and Interference
- Interferences can reduce sensitivity or cause false readings.
- Cross-sensitivities occur in various instruments.
- Filters can sometimes be used to prevent these issues.
Action Levels
- Triggers for specific actions based on known or unknown chemical releases.
- When action levels are reached, it may trigger:
- Removal of unprotected personnel
- Additional monitoring
- PPE adjustments
- Evacuation
- Action levels for Lower Explosive Limit (LEL) depend on whether the product is known or unknown:
- Known products may have higher LEL action levels.
- Unknown products require a more conservative approach.
- Multiple action levels may be established for response.
- Technicians re-evaluate the situation and take action based on changing readings.
Individual Monitoring and Area Monitoring
- Two main methods for determining exposure to chemical hazards:
- Individual Monitoring: Emergency responder carries an instrument for evaluation.
- Area Monitoring: Team effort, sampling the area systematically.
-
Individual Monitoring:
- Conducted with handheld equipment.
- Factors influencing results and safety:
- Location of the area
- Proximity of the product
- Oxygen concentrations
- Specific instrument response
- Risk-based approach
- Monitoring locations based on environmental conditions and hazard knowledge
- Vapor density considerations for interior or confined space monitoring
- Most chemicals have higher than one vapor density
- Wind direction and speed considerations for outdoor monitoring
-
Area Monitoring:
- Objective is to determine presence and concentration of products in an area.
- Incident Commander may request an average exposure potential for a defined area/zone.
- Portable equipment, or fixed equipment for long-term incidents.
- Instruments include photoionization detectors, oxygen sensors, explosivity meters, and chemical sensors for air concentration measurements.
Confined Spaces
- Spaces not intended for continuous occupation, with limited entry/exit openings, unfavorable ventilation, and potential for hazardous atmospheres.
- Testing for hazards before entering is mandatory.
Cargo Containers
- Potential for unknown materials being transported.
- Extreme care is necessary due to unknown conditions.
- Monitoring through open vents should be attempted.
Sampling Techniques
- Technicians may need to collect contaminant samples for:
- Medical treatment support
- Mitigation efforts
- Decontamination determination
- Incidents with criminal aspects may involve evidence collection through sampling.
Sample Collection
- Type of material and quantity determine sampling method and equipment.
- Safety samples collected per AHJ requirements may be used as evidence.
Field Screening Samples
- Field screens eliminate specific hazards before lab analysis.
- Ensure safety for packing, transporting, and lab testing.
- Consider potential for explosives.
- Check for crystals around caps/containers as indicators of potential shock-sensitive explosives/reactive chemicals.
- Field screening requires a well-ventilated work area.
- Leave enough material for lab testing for evidence purposes.
- Minimum field screening tests include:
- Corrosivity: pH paper
- Explosivity: Bomb squad checks
- Flammability: Combustible gas meter
- Oxidizer: Potassium iodide (KI) paper
- Radioactivity: Alpha, beta, gamma radiation checks
- Volatility: Photoionization detector (PID), Flame ionization detector (FID) for volatile organic compounds
Sampling Plans
- Include protocols for:
- Sample and evidence protection
- Field screening samples
- Labeling and packaging
- Sample/evidence decontamination
- Minimum of two individuals recommended:
- Sampler: Takes samples and handles equipment
- Assistant: Handles clean equipment and provides it to the sampler
- Law enforcement, lab, and transport operator responsible for safe packaging and transportation of evidence.
Chain of Custody for Sampling
- Continuous documentation of physical evidence possession for court admissibility.
- Evidence log documenting each possession change from discovery to court presentation.
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Description
This quiz covers the principles and technologies of detection and monitoring instruments used in emergency responses to chemical releases. It discusses the importance of equipment characteristics such as portability, durability, and safety features as well as the comprehensive evaluation process for selecting appropriate monitoring tools.
