OP 34 - LNG/ LPG Emergencies (05) Flashcards Preview

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Flashcards in OP 34 - LNG/ LPG Emergencies (05) Deck (32):

Occurs when a vessel containing a superheated liquid catastrophically fails, usually as a result of external fire exposure.

Boiling Liquid Expanding Vapor Explosion


What is any liquid with a boiling point below 130 degrees Fahrenheit?

Cryogenic Liquids. All are stored under extreme cold conditions. All become gases when exposed to ambient temps.


What is a flammable, colorless, cryogenic fuel which consists of approx 96% methane, 3% ethane, 0.5% propane + butane and the balance of nitrogen?

LNG - Liquefied Natural Gas.


If still colder than 150 degrees F LNG can remain close to the ground because some vapor is still heavier than air while cold, True or false?



What is any material having a vapor pressure not exceeding that allowed for commercial propane and is highly flammable, colorless (including refrigerated) mixture of gases?

LPG -Liquefied Petroleum Gas.


These hydrocarbon gases are odorless and tasteless, but because LPG is used mainly as a fuel, the odorant, ethyl mercaptan, is added as a safety feature to detect leaks, true or false?



Liquid LPG is 1.5 to 2 times heavier than air and will settle in low areas if not dispersed by the wind, true or false?



Although all ingredients of LPG are gases, it is always shipped and stored as a liquid, true or false?



What is a deflagration propagating in a location where the expanding combustion products are not confined?

Unconfined Vapor Cloud Explosion.


Who will supply experts on a 24-hour basis to assist with all emergencies involving LNG/LPG?

The gas supply department of PGW.


Full PPE including SCBA are to be worn at incidents involving LNG/LPG, true or false?



Incidents involving LPG should be approached from uphill/upwind to avoid low lying areas where vapors can collect, true or false?



If a vehicle stalls out while driven through a vapor cloud what should you do?

Don't try to restart it and move uphill/upwind.


When LNG/LPG is initially spilled on the ground it boils violently and vaporizes, but if leaking continues the ground will be refrigerated and leaking will slow, true or false?



If escaping LNG/LPG is not burning what should you do?

Close any valve available that can stop the flow of gas. Small copper lines can be flattened with non-sparking tools.


Fog lines can be used to disperse the vapors into a sage location, true or false?

True. Make sure not to spray directly into pools of spilled liquid and members must remain low and behind the fog lobe as protection.


When dealing with sizeable containers, how far does the US department of transportation recommend for evacuation?

At least 1/2 mile downwind. Also eliminate all sources of ignition.


Very cold LNG and all LPG vapors will accumulate in low lying areas such as sewers, basements, manholes, etc. true or false?



Should you extinguish a fire from a leaking tank?

No. Only if leakage can be stopped. Or if direct flame impingement on the vapor side of an exposes tank.


If escaping gas is on fire how much water should be applied and where?

At least 500 gpm, preferably from unmanned lines. 1st to direct flame impingement, then to piping and metal surfaces or adjoining vessels.


Who should you consult regarding the shutoff of the flow of gas?

Consult the driver of vehicle or plant operating personnel.


If the only shutoff valve is on fire what can the IC consider as a possible plan of attack?

Protecting a firefighting crew with fog streams while they access the shutoff.


The controlled burning of escaping LNG/LPG is commonly used. Sufficient water 500 gpm or more is applied to cool the shell. True or false?



Dry chemical and carbon dioxide portable extinguishers are NOT effective on minor LNG/LPG fires, true or false?

False. They can be used provided the supply of fuel can be stopped.


Flame impingement which weakens the metal is most often the cause of failure for LNG/LPG gas tanks, true or false?



If you can see peeled paint on a tank how hot is it?

Over 400 degrees F and on its way to a BLEVE.


How long will it take a tank to rupture under direct flame impingement without water being applied?

10 to 30 minutes.


What should you do if the relief valve discharge increases in the volume of fire, noise level increases, frequency of it opening increases, or the time of discharge lengthens?

Application of additional water is paramount, but if the relief valve stays open and doesn't close again upon application of water. All personnel must withdrawal to a safe distance.


If flame impinges in the vapor space of an LPG type pressure tank that is not cooled the tank may BLEVE before the relief valve opens, true or false?



What is the DOT's recommended safe distance to evacuate for a large container involved in fire?

At least 1 mile in all directions.


What should you do with portable cylinders exposed to fire?

Move them if possible to a safe location.


How should you always approach an LNG/LPG fire?

With the wind at your back.

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