Chapter 28 Class B Fires

Question 1

What is a flammable liquid?

Answer 1

The US DOT and TDG define a flammable liquid as one that has a flashpoint below 60.5 °C whereas NFPA and WHMIS define it as one that has a flashpoint below 37.8 °C.

60.5°C is a value that is used globally and recognized by the UN.

Question 2

Fires in open-topped oil tanks 3 Specific conditions

Answer 2

1. Boilover
2. Slopover
3. Frothover

Question 3

may occur spontaneously during fires in open-top tanks containing most types of crude oils and some synthetic heavy oil mixtures. This may occur when an explosion, usually caused by lightning, blows off the roof of a tank.

Answer 3

Boilover

Question 4

can result when a water stream is applied to the surface of a burning oil, provided the oil is viscous and its temperature exceeds the boiling point of water.

Answer 4

Slopover

Question 5

refers to the overflowing of a container, not on fire, when water boils under the surface of viscous hot oil.

Answer 5

Frothover

Question 6

Class B fires

Safety-Relief Devices

Answer 6

1. Safety- or Pressure-Relief Valves
2. Rupture Discs (Bursting Discs)
3. Fusible Plugs (Fuse Plugs or Melt Plugs)

Question 7

are usually a part of the cylinder held closed by a spring.

Answer 7

Safety- or Pressure-Relief Valves

Question 8

are discs, usually of metal, that burst and release the gas when the pressure of the cylinder reaches a certain level.

Answer 8

Rupture Discs (Bursting Discs)

Question 9

are activated by temperature rather than pressure. They are used in situations where heat could cause an explosive chemical reaction and are designed to release the gas before the hazardous reaction can begin.

Answer 9

Fusible Plugs (Fuse Plugs or Melt Plugs)

Question 10

Cylinders with manual control valves are equipped with either

Answer 10

a hand wheel or stem valve.

Question 11

Gas cylinder colour coding;
Green/Silver
Blue
Orange
Brown
Red
Grey

Answer 11

Green/Silver - Oxygen
Blue - Nitrous Oxide
Orange - Cyclopropane
Brown - Helium
Red - Ethylene
Grey - Carbon Dioxide

Question 12

Five common methods for containers to breach and spill their contents

Answer 12

1. disintegration,
2. runaway cracking
3. attachments open up
4. puncture
5. split/tear

Question 13

Container breach usually results in release of the contents. This release may happen slowly or quickly through…

4

Answer 13

1. detonation
2. violent rupture
3. rapid relief
4. spill/leak.

Question 14

13 Gases are lighter than air: Acronym – “4H MEDIC ANNA”

Answer 14

Hydrogen
Helium
Hydrogen Cyanide
Hydrogen Fluoride
Methane
Ethylene
Diborane
Illuminating gas
Carbon monoxide
Acetylene
Neon
Nitrogen
Anhydrous ammonia

Question 15

What is the vapor density of dry air

Answer 15

dry air has a vapor density of 1

Question 16

Container release types

Answer 16

1. hemispheric
2. cloud
3. plume
4. cone
5. stream
6. pool
7. irregular

Question 17

3 Basic types of pressure vessels

Answer 17

• Cylinders
• Tanks
• Lines

Question 18

Relief valve is venting due to:

Answer 18

● Overfilling
● Temperature difference
● Malfunction

Question 19

BLEVE

Answer 19

(Boiling Liquid Expanding Vapor Explosion)

Question 20

…is lighter than air, so it will rise and diffuse rapidly in open areas; in confined spaces, it will rise and collect from the ceiling downward. If you are using a gas detector in a confined area, sample the highest possible point in the room.

Answer 20

Natural Gas

Question 21

Natural gas concentrations of between “BLANK#1” and “BLANK#2” are explosive. In its compressed form (CNG), it is subject to a boiling liquid expanding vapor explosion (BLEVE).

Answer 21

5%, 15%

Question 22

Transmission lines carry gas from processing plants to local distribution centers. Gas in these lines is carried at pressures of…

Answer 22

700 to 9900 kPa (100 to 1440 psi)

Question 23

Class ‘B’ Fire Foam Percentages and Applications:

changed as per Bulletin

Answer 23

1.0%: On Shallow Hydrocarbon spills (such as gasoline, crude oil, diesel, aviation kerosene)
3.0%: On severe hydrocarbon (as above) and Polar solvent (alcohols, ketones, ethers) fires– products that mix with water)
Up to 6% for Hazmat vapor suppression (if required)

Question 24

4 Methods FOAM is Proportioned

Answer 24

Induction = In-Line Eductor (Old Pumps)
Injection = External Pump to force Foam into the fire stream.( New Salisbury Pumps)
Batch-Mixing = Pour the Foam directly into the Pump’s Tank
Premixing = Used in Fire Extinguishers

Question 25

2 Types of Foam Application Systems

Answer 25

**Manual System** = Eductor & Playpipe **Automatic System** = Built into the new Salisbury Pump

Question 26

Describe methods by which foam prevents or controls a hazard.

Answer 26

● Separation – Foam can be utilized to create a barrier between the fuel and the fire. ● Suppression – A blanket of foam robs a fire of its oxygen source and helps prevent the release of flammable vapors that might ignite. ● Cooling – As it breaks down into water, foam lowers the temperature of the fuel and nearby exposures.

Question 27

Explain principles by which foam is generated.

Answer 27

● Proportioning ● Foam generation ● Distribution.

Question 28

List the characteristics, uses and limitations of firefighting foams.

Answer 28

● The physical structure of foam is unstable – it can be broken down by physical force such as a water hose stream, or by some of the very chemicals you are trying to combat. ● Foam breaks down and vaporizes in the presence of heat and flame, so it must be applied in large quantities to compensate for this loss. ● Foam use in electrical fires is drastically limited because the solution is conductive. ● Foam can only be used on horizontal surface fires or in restricted spaces. ● Weather conditions, such as high winds, rain and extreme cold can greatly reduce the usefulness of foam.

Question 29

List different foam stream application techniques.

Answer 29

● Roll-on Method (Splashing) ● Bank-down Method (Baffle) ● Rain-down Method (Lobbing)

Question 30

List the characteristics of pressurized flammable gases.

Answer 30

● Pressure ● Diffusivity (tendency to spread freely) ● Low boiling points ● Colorless and/or odorless ● Creates static electricity when flowing

Question 31

List specific permanent markings on every gas cylinder.

Answer 31

● designed service pressure ● serial number ● inspection codes ● identification of the cylinder manufacturer ● empty (tare) weight ● date of testing and retesting.

Question 32

Give examples of safe havens before approaching flammable gas cylinder fires

Answer 32

1. Ground cover 2. Low lying areas (ditches, gullies) 3. Buildings 4. Treed areas 5. Fire pumper or truck, 6. and, as a last resort, Fog nozzle stream.

Question 33

What is LPG?

Answer 33

Liquid Petroleum Gas

Question 34

Burning Rates of Liquids and how it effects plan of attack

Answer 34

If we know the burning rate of a liquid, we can estimate the extent of area that will be involved in fire from a spill. When a spill is burning, the fire area will, at first, be small and then spread to a point of equilibrium where it will burn as fast as it is released.

Question 35

# Fire and Explosion Prevention Fire and explosion prevention measures include the following techniques or principles:

Answer 35

1. Exclusion of ignition sources 1. Exclusion of air (oxygen) 1. Storage of liquids in closed containers or systems 1. Ventilation to prevent the accumulation of vapor within the flammable range 1. Use of inert gas atmospheres instead of air.

Question 36

Ignitable liquid fires are extinguished by

Answer 36

1. shutting off the fuel supply 1. excluding air by various means 1. cooling the liquid to stop evaporation 1. a combination of these methods.

Question 37

What is the principle hazard of class 2 hazardous materials and how should they be stored

Answer 37

The principal hazard of Class 2 hazardous material is pressure vessel failure. Compressed gas containers should be stored in such a manner that the inlet to the safety relief valve is always in the vapor space.

Question 38

**Gas cylinder colour coding**

Answer 38

* Green/ Silver- Oxygen * Blue- Nitrous Oxide * Orange- Cyclopropane * Brown- Helium * Red- Ethylene * Grey- Carbon Dioxide ## Footnote Colour coding is secondary to the contents labeled on the cylinder

Question 39

Container Stresses

Answer 39

Stresses exerted on a container may be **thermal, chemical or mechanical** in nature. Alone or in combination, each type of stress can produce enough strain, pressure or deformity to cause the container to release its contents.

Question 40

What does vapor density dictate and how does that help us predict how a gas will behave when released into the atmosphere

Answer 40

Vapor density dictates whether a gas or vapor will sink, float, or rise in air. It represents the relative weight of a gas or vapor compared to an equal volume of dry air; dry air has a vapor density of 1.

Question 41

LPG (Liquid Petroleum Gas) | 4 points

Answer 41

1. A liquefied gas has a boiling point in the range of -90 degrees Celsius to -1.1 degree c. 1. Stored in pressurized vessels 1. Press. Range from 170-17000 kPa 1. Term LPG includes: Propane, Propylene, n-Butane, Isobutane, and Butylene.

Question 42

what Areas of Encounter might you find LPG (Liquid Petroleum Gas)

Answer 42

1. Balconies and backyards 1. Roadways 1. Railways 1. Storage facilities-gas stations 1. Gas plants 1. Forklifts/warehousing

Question 43

Emergencies Involving Propane procedure

Answer 43

1. Approach leaking and burning propane from upwind. 1. Keep people out of the vapor area. Evacuate to a distance of 60 meters (200 ft.) anyone not directly involved with incident response. Assign someone to make sure no one comes any closer. 1. Eliminate all sources of ignition. 1. Consider igniting escaping propane liquid or vapor. A controlled fire may be safer than an 1. uncontrolled vapor cloud. 1. Keep pipes, tanks, valves, and combustible exposures cool and well soaked. 1. Let the propane burn until it can be shut off.

Question 44

Propane and Fuel Oil Shut-off Procedures

Answer 44

1. Locate the storage tank or cylinder outside the building. 1. Look for the shut-off valve on or near the tank; this is usually a thread valve that can be turned by hand. 1. Ideally, a utility representative should shut off this utility. 1. Do not turn the utility on again.

Question 45

**...carry the natural gas from the local distribution center to consumers. The mains are buried in streets and alleys, and they carry gas at pressures between...**

Answer 45

* Distribution mains * 2 and 550 kPa (1/4 to 80 psi)

Question 46

...carry the gas from the distribution main to individual buildings. These lines may be plastic or lead pipes, 16 to 89 mm (5/8 to 3 in.) in diameter.

Answer 46

Service lines

Question 47

Natural gas may contribute to an emergency in four ways:

Answer 47

1. Gas escaping outside 1. Gas burning from an outside piping system 1. Gas escaping inside 1. Structural fires involving a gas system

Question 48

In situations where the supply of gas must be controlled before the arrival of gas company personnel, you should limit your actions to...

Answer 48

turning off the service line valve.

Question 49

Gas Shut Off Valves general rule

Answer 49

if a valve is turned off leave it off

Question 50

a distillate of natural gas, is also a non-toxic but asphyxiant gas.

Answer 50

Propane

Question 51

The ignition temperature of propane is

Answer 51

very low (450° C; 842° F), so it ignites easily.

Question 52

When a gas cylinder is exposed to flame...

Answer 52

**apply solid streams of water from their maximum effective range until the cylinder’s relief valve closes.** The best way to do this is to direct a stream of water along the top of the tank, above the level of the contained liquid, so that water runs down both sides, thus cooling the vapor space of the tank.

Question 53

# Class B fires Water as a Mechanical Tool

Answer 53

Fog streams can be used to dilute and disperse vapors and can, to some extent, move vapors to a more desirable location.

Question 54

Water as a Protective Cover

Answer 54

1. Advance the water stream under progressively wider fog patterns. 1. Use slow, deliberate movements. 1. Have ready a backup line supplied by a separate pump and water source. This provides added safety in the event the other line fails or additional cooling of the container is required.

Question 55

The pump pressure at the eductor must be What kPa to create the ‘venturi’ effect

Answer 55

1400