01 Why We Use Water

Question 1

Water acts in ____________ and ____________ ways that allow FFs to use it to extinguish fires.

Answer 1

Predictable / Repeatable

Question 2

Primary use of water to FFs?

Answer 2

Cool burning material

Question 3

British Thermal Unit (BTU)

Answer 3

The amount of heat required to raise the temp of 1 pound of water 1 degree.

Question 4

Water can also extinguish fires by

Answer 4

Smothering or diluting

Question 5

Water smothers by…

Answer 5

turning to steam in a confined space. Steam replaces air (oxygen).

Question 6

Smothering a fire is also known as an

Answer 6

Indirect Attack

Question 7

At 212 degrees water vapor will expand to

Answer 7

1,700 times its original volume

Question 8

At 500 degrees water will expand to

Answer 8

2,400 times its original volume

Question 9

Properties of Water

Answer 9

1. Water is nearly incompressible.
2. Water seeks its own level
3. Water has weight
   
   • 62.5 pounds / ft3
   • 8.35 pounds / gallon

Question 10

Disadvantages of water

Answer 10

1. Relatively high surface tension
2. It freezes
3. Conducts electricity
4. Reacts violently with some chemicals
5. Is not viscous (doesn’t smother fires well)

Question 11

1 cubic foot of water equals how many gallons? How many cubic inches?

Answer 11

7.48 / 1728

Question 12

1 gallon of water holds how many cubic inches?

Answer 12

231

Question 13

Column of water 1in x 1in x 1ft weighs?

Answer 13

0.434 pounds / Will need to be 2.304ft tall to weigh 1 pound

Question 14

Pressure

Answer 14

The amount of force applied

Question 15

Force

Answer 15

the amount of energy or weight applied at a given spot

Question 16

Pressure is defined as:

Answer 16

Force per unit area

Question 17

Static Pressure

Answer 17

pressure of water when it is not moving

Question 18

Flow Pressure

Answer 18

Pressure of water after the nozzle is opened and the water is moving

Question 19

Flow pressure is the amount the intake pressure gauge __________ after the attack line is opened.

Answer 19

drops

Question 20

Residual Pressure

Answer 20

Remaining pressure in distribution system after water is flowing

Question 21

Rules Governing Fluid Pressure

Answer 21

1. Fluid pressure is perpendicular to any surface on which it acts
2. The pressure at any point in a fluid at rest has teh same intensity in all directions
3. External pressure applied to a confined liquid is transmitted undiminished in all directions
4. The downward pressure of a liquid in an open container is proportional to the depth of the liquid
5. The downward pressure of a liquid in an open container is proportional to its density
6. The downward pressure of a liquid on the bottom of an open container is independent of teh shape or size of the container

Question 22

To find gallon capacity of containers:

Answer 22

7.48 x V (LxWxH or πr2H)