Hazmat Flashcards
The status of containers involved will likely influence the
Type and extent of defensive practices undertaken
First responders should constantly assess the status of
Any containers that may be involved
First responders must evaluate the ———-where the container is located and any ——- that may be applied to containers
Environment
Stress
Types of stress
Thermal mechanical chemical
When attempting to prevent a release of hazardous materials first responders should always remember that
Pressurized containers usually present the greatest danger
If the valve on a compressed gas cylinder is damaged gas or vapor may be released at a rate and volume
Faster than it would be from a pressure relief device
Physical damage to a container wall may appear as a crease dent or gouge and the extent of damage will influence the extent to which
The integrity of the container has been weekend
Damage is especially troublesome when it occurs at
Weld lines or places where pieces of metal are joined
If a damaged and therefore weakened container cannot withstand its internal pressure immediately after an accident the container will likely
Explode prior to the arrival of first responders
If the internal pressure increases sufficiently to a point just above that which the weakened container wall can resist the container may
Fail without warning
Liquefied gases stored at normal atmospheric temperatures and pressures are already
Boiling inside their containers
Once the liquid inside is above it’s boiling point the containers become
Pressure cookers with the potential for disastrous consequences
The weakening of a container wall from flame impingement usually occurs when the flame contacts
The vapor space which is usually the upper portion of a container
Whenever containers are exposed to a fire with a decrease in container strength and increase of internal pressure first responders must remember that
Operation of a pressure relief valve is no guarantee that the container will not explode
The sound of gas and vapor escaping from an operating pressure relief device during a fire will increase in both ———-as internal pressure continues to rise due to an external heating. This change in sound should serve as a warning to first responders that they may need to——
Volume and pitch
immediately evacuate the area
Containers intended to store liquids at normal temperatures and pressures usually do not
Unless
Present a danger from excessive internal pressure
There is an external heating or chemical reaction of the contents inside the container
External heating can occur from exposure to
Direct sunlight or fire
Long-term incidents have a potential for the internal pressure of containers to fluctuate due to changes in
Weather conditions and time of day
Non-pressure containers with liquid or solid materials may also be subject to excessive internal pressure from chemical reactions that occur as a result of
Improper handling of unstable materials
non pressure containers: Metal containers may develop a ——as internal pressure increases and stresses the container wall
Metallic pinging sound
The ends of ——– are usually the weakest locations and therefore the most dangerous
Non-pressure containers
Non-pressure containers: if the container of liquid burst it will usually do so at——— which may then cause the container to travel in——-
One of its ends
travel in the opposite direction at a high rate of speed
Nonpressure containers: There may be little first responders can do to prevent a release from a container that is
Already under pressure or
when the internal pressure is steadily increasing
Evacuating the area a safe distance may be the only option
Containers under pressure can release their contents
Without warning