TB 11 Pressured Dry Chemical Fire Extinguishers

Question 1

The chemical itself is ______ especially treated to make it resistant to caking and moisture, and capable of being readily dispersed into a fire-killing cloud.

Answer 1

baking soda (sodium bicarbonate, NaHCO 2 )

Question 2

Dry Chemical, in the presence of heat, releases ____ and _______ which provides a ______ action.

Answer 2

carbon dioxide / water vapor / smothering

Question 3

Heat is absorbed by both the solid particles and water vapor which provides ____.

Answer 3

cooling

Question 4

The chemical chain reaction of combustion is ___. That is, the dry chemical inactivates the intermediate products necessary for continued combustion.

Answer 4

interrupted

Question 5

Generally dry chemical is most effective on fires involving ______.

Answer 5

flammable liquids, gases, and liquefied gases.

Question 6

It is the fastest and most spectacular extinguishing material for ____.

Answer 6

spilled fuel areas

Question 7

Dry chemical is effective on fires involving ____, natural gas leaks, and liquefied flammable gas leaks and spills.

Answer 7

deep-layer flammable liquids

Question 8

it will extinguish fires involving ___ even when they are burning under high pressure.

Answer 8

bottled gases

Question 9

Dry chemical is approximately ____ as effective as CO2 on hydrocarbon fires, including methane, for a given size extinguisher.

Answer 9

twice

Question 10

This extinguisher is especially suitable for use on fires in ___ above stoves, when applied into the lower end of the duct.

Answer 10

grease ducts

Question 11

A cloud of dry chemical is similar to a ____, in that a flame cannot pass through a cloud of particles in proper concentration.

Answer 11

flame arrestor

Question 12

When a car fire involving occupants is encountered, there are certain advantages to using dry chemical; the powder can be used as a ____ to quickly move in on the fire and rescue the occupants

Answer 12

heat screen

Question 13

The powder will absorb the heat, and anyone in the area can ____ through the cloud of dry powder.

Answer 13

safely-walk-out

Question 14

The dry chemical in these extinguishers can also be used to ____.

Answer 14

neutralize acid spills

Question 15

When an acid spill is encountered, pull the locking pin, hold the nozzle ____ above the acid, squeeze the valve just enough to allow the powder to flow gently from the nozzle and spread the powder over the surface of the acid.

Answer 15

2 or 3 feet

Question 16

A disadvantage of using dry chemical is its ____ after extinguishment.

Answer 16

lack of control

Question 17

Within a few seconds the powder may drift away leaving the fuel completely exposed for a ____.

Answer 17

reflash.

Question 18

Dry chemical is ___.

Answer 18

non-toxic

Question 19

This extinguisher consists of:

a. a shell of heavy gauge steel, tested to ____
b. a nylon reinforced hose
c. a positive control squeeze grip valve.
d. a nozzle which shapes the dry chemical into a ____ fan stream
e. an air pressure gauge protected by a gauge guard.

Answer 19

600 psi / 60 degree

Question 20

The shell is filled with ____ of dry chemical and then pressurized to approximately ____ with compressed air.

Answer 20

twenty (20) pounds / 165 psi

Question 21

This extinguisher has a rating of 20-B,C, meaning that in the hands of an average operator it is capable of extinguishing a _____ deep-layer Class B fire, and is safe for use on fires involving energized electrical equipment.

Answer 21

20 square foot

Question 22

The discharge time of a 20- pound dry chemical extinguisher with the valve fully open is _____.

Answer 22

10 seconds.

Question 23

The 20 pound CO 2 extinguisher in use on the Department will last _____.

Answer 23

60 seconds

Question 24

Best results are obtained with this type extinguisher by working from windward side of fire and ___ powder in over the fire.

Answer 24

floating

Question 25

This can be done by holding the nozzle about ____, aiming the nozzle straight forward or slightly upward (rather than down into the fire) then giving a short blast of powder’

Answer 25

waist height

Question 26

The extinguisher has an effective range of approximately ____.

Answer 26

15 to 20 feet

Question 27

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 ______.

Answer 27

6 to 8 feet

Question 28

The extinguisher will function effectively only so long as the air pressure is between ____.

Answer 28

125 to 175 psi.