Atmospheric Monitoring Flashcards
Hazardous atmospheres
Flammable environments (Including gases such as acetylene and LPG; vapours such as petrol, ethanol and acetone; and flammable dust such as coal dust and wheat dust)
Oxygen enriched environments (Unusual but hazardous due to the fierce burning rate of any fire in this environment)
Oxygen deficient environments (When oxygen in the air is below 19.5% can lead to unconsciousness and death in a few minutes)
Toxic chemical contaminants and irritants (Such as carbon monoxide (CO), sulphur dioxide (SO2), ammonia (NH3), and oxides of nitrogen (NOx))
Elevated temperature environments (Can burn the airways and lungs when inhaled causing pulmonary oedema - fluid in the lungs)
Radioactive environments (Such as medical facilities or radioactive good being transported)
Particulates in the air (Such as dust or aerosols created from the processing of flour, coal, plastics, metals etc)
Airborne contaminant groups
Airborne contaminants are generally broken into 3 major groups depending of their physical property.
These are:
Gases
Vapour
Aerosols
Gases definition and examples
Gases are substances that are too volatile to exist as a liquid or solid at typical air temperature or pressures.
Examples:
Hydrogen (H2)
Helium (He)
Methane (CH4)
Acetylene (C2H2)
Propane (C3H8)
Nitrogen Dioxide (NO2)
Vapour definition and examples
Vapours are generally the evaporative product of volatile (easy to evaporate) liquids.
Examples:
Acetone
Petrol
Benzene
Styrene
Ethanol
Aerosols definition and examples
Aerosols consist of very small solid particles or liquid droplets that are dispersed in a gas stream (usually the atmosphere). The particles are small enough to remain suspended in the air and be carried along by the air currents.
Examples:
Flour
Coal
Plastics
Metals
3 types of measurement and when they’re used
When monitoring toxicity the unit used is part per million expressed as ppm.
When monitoring for oxygen levels the unit used is volume percent of the atmosphere expressed as v/v%.
When monitoring for flammability the unit used is the percent of the lower explosive limit expressed as % of the LEL.
Acceptable oxygen range
19.5 - 23.5%
Explain LEL
The LEL (lower explosive limit) is the lowest concentration of a gas or vapour (expressed as a volume percentage in air) that will burn or explode if an ignition source is present.
Explain UEL
The UEL (upper explosive limit) is the highest concentration of a gas or vapour (expressed as a volume percentage in air) that will burn or explode if an ignition source is present.
Explain flammable range
The flammable range is the concentration range of a gas or vapour (expressed as a volume percentage in air) that will burn or explode if an ignition source is present.
What does ES stand for
Exposure standards (ES) indicate the safe airborne concentrations of individual chemical substances in the general occupational environment. Such concentrations should not impair the health or cause discomfort to workers for both long and short term exposure.
Define TWA
Time-weighted average
This is an average concentration value for a substance to which a worker can be exposed for 8 hours per day, 5 days week with no short or long term harm.
Define STEL
Short-term exposure limits are concentrations to which a worker can be expected for up to 15 minutes at a time without suffering:
Irreversible tissue damage
Irritation of, or damage to the airway
Narcosis (sleepiness)
Exposure should not occur for longer than 15 minutes. A maximum of four 15min exposures are allowed per day with a minimum of one hour between exposures.
Define PLV
Peak limitation value is a concentration that if exceeded, then the atmosphere is considered occupationally unacceptable.
Define IDLH
Immediate danger to life and health is defined as:
An atmospheric concentration that poses immediate threat to life or would cause irreversible or delayed adverse health effects OR would interfere with an individual’s ability to escape from a dangerous atmosphere.
MicroRae Operational alarm table
