TB 11 - Dry Chem Fire Extinguisher

Question 1

What chemical is found in dry chemical extinguishers (baking soda)?

Answer 1

Sodium bicarbonate (NaHCO 2)

Question 2

Dry chemical extinguishers are the fastest and have the most spectacular knock down for what areas?

Answer 2

Spilled fuel areas

Question 3

Generally dry chemical extinguishers are effective on fires involving what?

Answer 3

Flammable liquids, gases, and liquified gases

Question 4

Dry chemical extinguishers are how much more effective than CO2 extinguishers on hydrocarbon and methane fires?

Answer 4

Twice as effective

Question 5

It is desirable to have what for complete extinguishment of Class A fires, but if not available large quantities of dry chemical may be used for complete extinguishment?

Answer 5

Water

Question 6

Dry chemical extinguishers are similar to what in that the flame cannot pass through a cloud of particles in proper concentration?

Answer 6

A flame arrestor

Question 7

The sodium bicarbonate found in dry chemical extinguishers are especially treated to make it resistant to what?

Answer 7

Caking and moisture

Question 8

Dry chemical, in the presence of what, releases carbon dioxide and water vapor which provides a smothering action?

Answer 8

Heat

Question 9

What is absorbed by both solid particles and water vapor which provides cooling?

Answer 9

Heat

Question 10

Dry chemical extinguishers are effective on fires involving?

Answer 10

Deep layer flammable liquids
Natural gas leaks
Liquified flammable gas leaks and spills

Question 11

There has been an increasing use of dry chemical extinguishers on what fires, especially textile fibers such as cotton?

Answer 11

Class A

Question 12

When using the dry chemical extinguisher on Class A fires, it serves primarily for what?

Answer 12

Rapid control of the fire

Question 13

When using a dry chemical extinguisher during a car fire involving occupants it can be used as a what?

Answer 13

Heat screen

Question 14

The use of a dry chemical extinguisher as heat screen should not be used unless how many fireman are present?

Answer 14

2, one for rescue and one to provide protective cover

Question 15

The dry chemical extinguisher can be used for acid spills, pull the locking pin and hold the nozzle how many feet above the acid spill to spread the powder over the surface of the acid?

Answer 15

2-3 feet

Question 16

When fires are encountered with gases heavier than air (butane and propane), the fire ordinarily should not be extinguished until what can be obtained due to potential of explosions and further extension of the fire?

Answer 16

Control of the gas

Question 17

A disadvantage of dry chem extinguishers is its lack of control after extinguishment, within how many seconds will the powder drift away leaving the fuel completely exposed for a reflash?

Answer 17

A few seconds

Question 18

The dry chemical extinguisher is ineffective on what type of fires?

Answer 18

Metal such as magnesium and sodium

Question 19

Is dry chemical toxic or non toxic?

Answer 19

Non toxic

Question 20

Because of the dry chem dielectric characteristics, the dry powder can be used safely on what such as fires involving oil cooled electric switches and transformers?

Answer 20

Electrical fires

Question 21

Because of the dry chems slightly abrasive and corrosive properties it should be used with care on what kind of fires?

Answer 21

Fine electrical or electronic gear

Question 22

The dry chem extinguisher consist of a heavy steel gauge shell and is tested at what psi?

Answer 22

600 psi

Question 23

The nozzle on the dry chemical extinguisher is shaped into what degree fan stream?

Answer 23

60 degree

Question 24

The shell of the dry chemical extinguisher is filled with how many pounds of dry chem?

Answer 24

20 pounds

Question 25

What is the dry chem extinguisher is pressurized to approximately what psi with compressed air?

Answer 25

165 psi

Question 26

The extinguisher has a rating of 20-BC which means?

Answer 26

Capable of extinguishing 20 square feet deep layer Class B fires and safe for use on fires involving energized electrical equipment

Question 27

What is the discharge time of the 20 pound dry chem extinguisher with the valve fully open?

Answer 27

10 seconds

Question 28

How long will the 20 pound CO2 extinguishers last when discharged?

Answer 28

60 seconds

Question 29

When using the dry chem extinguisher on a fire, the valve normally should be what to maintain proper discharge and to preclude any possibility of the balance becoming clogged?

Answer 29

Wide open

Question 30

The best results are obtained with the dry chem extinguisher by working from what side of the fire and floating powder in over the fire?

Answer 30

Windward

Question 31

When discharging the dry chem extinguisher, aim the nozzle straight forward or slightly upward towards the fire rather than down with short blasts and the extinguisher should be held at what height?

Answer 31

Waist height

Question 32

With a side-to-side sweeping action, cover the entire area of fire, with each sweep extend slightly where of the fire area to preclude any flashback?

Answer 32

Beyond the perimeter

Question 33

The dry chem extinguisher has an effective range of approximately how many feet?

Answer 33

15-20 feet

Question 34

To prevent splashing when using on depths of flammable liquid, care should be taken to direct the initial discharge from a distance not closer than how many feet?

Answer 34

6-8 feet

Question 35

The dry chem pressure gauge should be checked how often for a full charge?

Answer 35

Daily

Question 36

The dry chem extinguisher will function effectively as long as the air pressure is between what psi?

Answer 36

125-175 psi

Question 37

What should be done monthly to the dry chem extinguisher?

Answer 37

Inverted and shaken to preclude any possibility of the chemical caking

Question 38

The dry chem extinguisher should be tagged with an F-175 tag and sent to the shops when?

Answer 38

To be recharged with air or dry chemical