[Home] [Master Table of Contents]
[SPCCP Index] [Appendix D Index]
Appendix D - Training Program
Air Monitoring Principles
Objectives/Samples of Behavior:
Explain the difference between direct and indirect reading instruments.
Explain the use of direct and indirect reading instruments at hazardous waste sites.
Differentiate between personal and area monitoring.
Determine when periodic monitoring is needed.
A. Purposes of Air Monitoring
Hazards & risks to public & personnel
Personal protective equipment selection
Site work zones
Effects on environment
Mitigation actions
B. General Types of Air Monitoring
DIRECT
INDIRECT
C. Desired Characteristics of Field Instruments
Portable and rugged
Easy to operate
Inherently safe
Reliable and useful results
Response time
Sensitivity
Selectivity
Accuracy
Precision
D. Direct Reading Instruments - General
Disadvantages/considerations
Variable results
Low end sensitivity problem
Only measure/detect specific classes of chemicals
Multiple contaminants
Interferences, relative response
Worker training
Recording of results
Not for compliance (Air Force)
Inherent safety approval area
Electrical devices such as portable air monitoring instruments are to be constructed in such a fashion as to eliminate the possibility of igniting a combustible atmosphere.
Hazardous atmospheres - National Electric Code
Definition of a hazardous atmosphere:
Concentration between the lower explosive limit and upper explosive limit (LEL - UEL)
Presence of ignition source
Exothermic reaction
Definitions
Intrinsically safe: Designed so that parts are not exposed to explosive atmosphere, or if there is insufficient energy for ignition.
Explosion proof: Designed to contain an explosion and cool gases to prevent spread.
Purged system: Inert gas-filled system; positive pressure to prevent explosive gases or vapors from entering.
Hazardous atmospheres & locations - inherent safety
Class
I
Combustible gases and vapors
II
Combustible dusts
III
Combustible fibers and flyings
Group
A, B, C, D
Gases and vapors found in Class I atmosphere
E, F, G
Dusts found in Class II atmosphere
Division
1
Location in which hazardous concentrations exist continuously, intermittently, or periodically under NORMAL operating conditions
2
Location in which hazardous concentrations do NOT normally exist under normal operating conditions
Instrument protection criteria
Class I, Groups A, B, C, & D, Division 1
"Intrinsically safe"
"Explosion-proof"
"Purged system"
Class I, Groups A, B, C, & D, Division 2
"Non-incendive"
Class II, Groups E, F, & G, Division 1 & 2
"Dust-ignition proof"
E. Oxygen Indicators
To determine:
Types of respiratory protection
Combustion risk
Use of other instruments
Presence of contaminants
F. Combustible Gas Indicators (CGIs)
To determine:
Risk of fire/explosion
Indication of contaminants
Reads % LEL
Combination units
Calibration gas & conversion charts, e.g., methane vs combustible gas to be measured
Interpretation of results - reading of 100% for example
G. Toxic Atmosphere Monitors
Detector tube system
Length of stain/color change = concentration
Different # pump strokes for different chemicals / concentrations - specified in manufacturer's instruction
Monitors for specific agents (e.g. CO, hydrogen sulfide)
Total vapor analyzers
Gas chromatograph
H. Site Monitoring
Monitoring variables
Inside or outside?
Temperature
Wind
Rain - humidity
Unknown conditions
Sequence
Oxygen deficiency - 1st - 19.5%
Explosive atmosphere - 2nd - 25% LEL for levels A & B - (10% LEL foe level C - when site has been characterized sufficiently to downgrade level)
Radiation - 3rd = 1 mR/hr
Level B: minimum for initial entry into unknown area
Perimeter Monitoring
Check for off-site impacts: public health
Evaluate site clean areas
Site safety plan dictates need
Periodic monitoring
Locate sources of contamination
Working in obvious contamination
When new contaminants are handled
Different operations, drum opening vs well drilling
When work begins on a different portion of the site
Personal Monitoring
Monitor "high risk" employees
OEL monitoring - compliance
Respirator protection factors
After the fact - legal reasons