Chapter 6- Water

Question 1

What is the order from largest to smallest of water supply pipes?

Answer 1

1. Feeders
2. Secondary Feeders
3. Distributors

Question 2

Is there less FL in a water distribution system when fire hydrants are supplied by one direction or two (or more) directions?

Answer 2

There is much less FL when a hydrant is supplied from two or more directions.

Question 3

A fire hydrant that receives water from only one direction is called….

Answer 3

A dead-end hydrant.

Question 4

When a fire hydrant receives water from two or more directions it is called…

Answer 4

Circulating feed or looped line.

Question 5

To ensure sufficient water, how many primary feeders should run from the source of supply to the high risk industrial districts?

Answer 5

Two or more.

Question 6

In residential areas, what is the recommended size for fire hydrant supply lines?

Answer 6

6 inches with 8-inch cross-connecting mains at intervals of not more than 600 feet.

Question 7

What is the recommended size water mains in industrial areas?

Answer 7

8-inch mains with 8-inch cross-connecting mains every 600 feet.

Question 8

How often should water control valves be operated to keep them in good working condition?

Answer 8

At least once a year

Question 9

Valves for water systems are broadly divided into what two types?

Answer 9

Indicating and non indicating

Question 10

Valves in private protection systems are generally indicating or non indicating?

Answer 10

Indicating

Question 11

Name the two types of indicating valves.

Answer 11

PIV-post indicator valve: Open/Shut

OS&Y-outside stem/screw and yoke: The threaded portion of the stem is out when the valve is open

Question 12

The OS&Y valve is most commonly used in what application?

Answer 12

Sprinkler systems

Question 13

What two types of valves are used in water distribution systems?

Answer 13

Gate valves

Butterfly valves

Question 14

Name the types of materials that can be used for underground water pipe.

Answer 14

Cast iron

Ductile iron

Asbestos cement

Steel

Plastic

Concrete

Question 15

Which materials should be used for added strength in underground water pipes in unstable or corrosive soils?

Answer 15

Steel pipe

Reinforced concrete pipe

Question 16

What two factors govern the heat absorbability of water?

Answer 16

Specific Heat

Latent Heat of Vaporization

Question 17

Water has the ability to extinguish fire in several ways. Name them and explain.

Answer 17

The primary way is cooling, or absorbing, heat from a fire.

Another way is by smothering (excluding oxygen).

Question 18

When using water to smother a fire in combustible liquids, the specific gravity must be higher or lower than 1?

Answer 18

The specific gravity must be higher than 1. Floating liquids will not be smothered by water.

Question 19

How does the exposed surface area affect water’s ability to act as an extinguishing agent?

Answer 19

The greater the surface area of the water exposed to heat, the greater the heat absorbed.

Question 20

What is the definition of Specific Heat?

Answer 20

The measure of the heat-absorbing capacity of a substance.

Question 21

What are the two units of measurement used to measure heat transfer? Which do we use?

Answer 21

British Thermal Units (BTU’s)

Joules 1 BTU = 1.055 kJ

We generally use BTU’s.

Question 22

Define BTU.

Answer 22

The amount of heat required to raise the temperature of 1 pound of water 1 degree (F). [starting at 60 degrees]

Question 23

Define Specific Heat.

Answer 23

The specific heat of any substance is the ratio between the amount of heat needed to raise the temperature of a specified quantity of a material and the amount of heat needed to raise the temperature of an identical quantity of water by the same number of degrees.

Question 24

Define latent heat of vaporization.

Answer 24

The quantity of heat absorbed by a substance when it changes from a liquid to a vapor.

Question 25

Define Boiling Point.

Answer 25

The temperature at which a liquid absorbs enough heat to change to a vapor.

Question 26

At sea level, water begins to boil or vaporize at what temperature?

Answer 26

212 degrees. However, vaporization does not completely occur the moment water reaches the boiling point. Each pound of water requires about 970 BTU of additional heat to completely convert to steam.

Question 27

Water expands when it converts to steam. At 212 degrees, what is this expansion?

Answer 27

1700 times its original volume. In hotter atmospheres, steam expands to even greater volumes.

Question 28

Water is heaviest close to its freezing point and lightest close to its boiling point. Ordinary water is generally considered to weigh how much per gallon?

Answer 28

8.33 pounds per gallon.

Question 29

Define specific gravity.

Answer 29

The density of liquids in relation to water.

Less than 1: lighter than water
Greater than 1: heavier than water

Liquids with a specific gravity of 1 it mixes evenly with water.

Question 30

Most flammable liquids have a specific gravity of less than 1 or greater than 1?

Answer 30

Most flammable liquids are less than 1.

Question 31

Define pressure.

Answer 31

Force per unit area.

Question 32

Define force.

Answer 32

A simple measure of weight usually expressed in pounds. To understand force you must know the weight of the water and the height the column of water occupies.

Question 33

What is the weight of one cubic foot of water?

Answer 33

62.5 pounds

Question 34

Define residual pressure

Answer 34

The part of total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, hose, and adapters.

Question 35

Above sea level, atmospheric pressure drops by….

Answer 35

0.5 psi per 1000 feet.

Question 36

When hoses are the same size, what is the relation between FL and the flow?

Answer 36

When hoses are the same size, FL varies with the square of the increase in flow.

200 gpm to 400 gpm (2x) = 4 times inc in FL