Propane Flashcards
What is the molecular formula of propane?
C₃H₈
What is the boiling point of propane at atmospheric pressure?
-44°F (-42°C)
What is the flashpoint of propane?
-156°F (-104°C)
Is propane heavier or lighter than air?
Heavier than air (vapor density = 1.52)
What is the flammable range of propane in air?
2.1% - 9.5%
What is the autoignition temperature of propane?
~896°F (~480°C)
What type of light or detection method cannot detect propane due to its ionization potential (IP)?
A photoionization detector (PID) cannot detect propane because its IP is 11.07 eV
How can mercaptans (odorant in propane) be detected using a PID?
Mercaptans have a lower ionization potential (IP) and may be visible on a PID lamp if within its range.
What is propane’s specific gravity as a liquid?
~0.5 (lighter than water)
What is propane’s behavior when released in water?
Propane is insoluble, floats on water, and quickly vaporizes.
Why is propane considered an asphyxiation hazard?
It displaces oxygen in enclosed spaces, leading to suffocation.
Why is propane classified as an explosive hazard?
Its low end flammable range make it highly prone to explosive ignition when mixed with air.
Can propane cause cold injury?
Yes-
Liquid propane can cause severe frostbite on contact due to rapid heat absorption during vaporization.
What are some of the common sizes of propane tanks?
20 lbs (grill), 33 lbs (forklift), 100 lbs (residential), and bulk tanks (250-1,000+ gallons)
What is the maximum fill percentage of a propane tank, and why?
80% to allow for thermal expansion and prevent overpressurization.
How is propane stored in a tank?
As a liquid under pressure with vapor on top.
What happens if a propane tank is exposed to fire without proper venting?
It can result in a BLEVE (Boiling Liquid Expanding Vapor Explosion).
What are propane tanks typically made of?
Steel or aluminum, designed for high-pressure containment.
What are the primary valves on a propane tank?
- Service valve: Supplies vapor or liquid propane to downstream equipment.
- Pressure relief valve (PRV): Releases propane if tank pressure exceeds safe limits.
- Fill valve: Used to fill the tank with liquid propane.
- Vapor return valve: Balances pressure during filling or transfers.
- Fixed liquid level gauge: Shows if the tank is at the correct fill level.
What is the function of the service valve?
Controls the release of propane to appliances or hoses.
What is the function of the pressure relief valve (PRV)?
Automatically vents propane to prevent overpressurization during overheating or overfilling.
What is the function of the fill valve?
Also called splash valve
Allows liquid propane to be introduced into the tank during refueling.
What is the function of the vapor return valve?
Used during filling to allow excess vapor to return to the source and prevent overpressurization.
What is the fixed liquid level gauge, and how is it used?
A small bleeder valve that emits liquid propane when the tank is filled to 80%, indicating a full tank.
What DOT placard is required for propane during transportation?
Class 2.1 Flammable Gas (red with flame symbol, UN 1075).
What UN number identifies propane?
UN 1075
What emergency response guidebook (ERG) number is used for propane?
ERG 115
What is the maximum allowable fill percentage for a propane tank?
80%
What are the key transport requirements for propane tanks?
- Must be secured
- Labeled with Class 2.1 placards
- Valves protected by caps or guards
Can propane be transported in enclosed vehicles?
Only if properly ventilated and secured to prevent movement or leaks.
What should be done if propane is leaking from a PRV?
Cool the tank with water while evacuating the area.
What is the recommended method for identifying propane leaks?
Use a combustible gas indicator or antifreeze to check for bubbles at connections.
How can you protect against a BLEVE during a fire?
Maintain cooling water streams on the upper parts of the tank and vent areas.
500gpm per area of flame impingement
What are the signs of a BLEVE?
- Loud hissing from PRV venting.
- Discoloration or bulging tank.
- Fire directly impinging on the tank.
What is the recommended PPE for a propane emergency?
Full turnout gear with SCBA.
What is the expansion ratio of liquefied propane when it vaporizes?
270:1 (liquid to gas).
What happens when propane undergoes ‘auto-refrigeration’?
Rapid vaporization causes propane to cool and potentially freeze surrounding areas, creating frost.
At what temperature does propane reach its boiling point?
-44°F (-42°C).
How does propane behave in windy conditions?
Propane vapors, being heavier than air, stay low to the ground but can be dispersed by wind.
What is the first step in managing a leaking propane cylinder or tank?
Shut off the service valve (turn right-tight).
What should you do if frost appears on the service line during a propane leak?
Use a fog stream to disperse vapors and prevent ignition.
Check service tree for leak and valves
What is a potential danger of an overfilled propane tank?
Lack of proper vapor space increases pressure, leading to venting from the pressure relief valve.
How do you mitigate an overfilled propane tank?
- Shut off the service valve.
- Remove service connections.
- Disperse vapors with a fog stream.
At what pressure does a relief valve on an ASME propane tank typically activate?
250 psi at 127°F.
At what pressure does a relief valve on a DOT propane cylinder typically activate?
375 psi at 161°F.
What are MC331 tanks designed to transport?
Liquefied propane and other liquefied compressed gases.
What is the capacity of bulk propane storage tanks?
Up to 30,000 gallons.
Where are emergency shut-offs located on an MC331 trailer?
On the left front and right rear of the trailer.
What is the purpose of vapor lines in bulk tanks?
Vapor lines allow pressure balancing and controlled vapor flow during operations.
What is the recommended initial isolation zone for a propane leak?
300 feet in all directions.
Why should fog streams be used during propane emergencies?
Fog streams help push vapors away and reduce ignition risks.
What PPE is required when responding to a propane emergency?
Full bunker gear, SCBA, pkp, charged hose line
What is the description of propane?
Propane is a colorless, odorless gas that becomes a liquid under pressure. Odorants like methyl mercaptan are added for leak detection.
Methyl mercaptan is responsible for the distinctive rotten egg smell associated with propane.
What is the boiling point of propane?
-44°F (-42°C)
What is the flammable range of propane in air?
2.1% to 9.5%
What is the expansion ratio of liquid propane to gas?
270:1
What is the vapor density of propane?
1.52 (heavier than air)
What is the specific gravity of liquid propane?
~0.5 (lighter than water)
What is auto-refrigeration in propane behavior?
Propane absorbs heat when vaporizing, creating frost or ice on surfaces.
Where do propane vapors typically collect?
In low-lying areas like basements, drains, or ditches.
How does temperature affect propane pressure?
As temperature increases, propane pressure increases.
What is the pressure of propane at 100°F?
190 psi
What activates the relief valve in ASME tanks?
Activates at 250 psi when internal tank pressure exceeds this threshold.
How is the service valve operated on ASME tanks?
Turn right (clockwise) to close; left (counterclockwise) to open.
What is the purpose of the fixed liquid level gauge (bleeder valve)?
Indicates when the tank is at 80% capacity during filling.
What happens if the pressure relief valve malfunctions?
It may continuously vent propane, or hold in propane escalating BLEVE risks.
What is the designation of DOT cylinders?
Categorized by the pounds of propane they hold (e.g., 20 lbs, 33 lbs, 100 lbs).
What is the relief valve setting for DOT cylinders?
Activates at 375 psi when pressure exceeds this limit.
What does the Overfilling Prevention Device (OPD) do?
Prevents overfilling by stopping liquid propane from exceeding 80% capacity.
How do you verify that the propane fill level does not exceed 80% in DOT cylinders?
Using the bleeder valve (fixed liquid level gauge).
What does a hissing sound from the relief valve indicate?
Continuous venting sound indicates pressure is too high.
Fill in the blank: Propane vapors are _______.
Heavier than air
True or False: The service valve on DOT cylinders opens by turning right.
False
What is the typical pressure at which the relief valve activates in DOT cylinders?
375 psi
What is the significance of a fixed liquid level gauge during refueling?
It indicates when the tank is at 80% capacity.
What are the common colors of vapor and liquid lines on bulk storage propane?
Liquid red
Vapor yellow
