Chapter 5 - Principles Of Water

Question 1

Waters freezing point

Answer 1

Below 32F (0C)

Question 2

Waters boiling point

Answer 2

Above 212F (100C)

Question 3

How much does water weigh?

Answer 3

Ordinary fresh water is considered to weigh 62.4lbs/ft 3 or 8.3lbs/gallon

Question 4

Water extinguishes fire in several ways

Answer 4

-It cools and absorbs heat in a fire
-can smother the oxygen from a fire
-can also smother combustible liquid fires whose specific gravity is higher than 1 (heavier than water)
-smothering may also occur when water converts to steam in a closed space

Question 5

Water converted to steam converts to?

Answer 5

1,700 times it’s original volume

Question 6

Pressure

Answer 6

Force per unit area exerted by liquid or gas measured in pounds per square in (psi) or kilopascals (kPa)

Question 7

Force

Answer 7

Simple measure of weight, usually expressed in pounds or kilograms

Question 8

Principles of pressure
First principle

Answer 8

Fluid pressure is perpendicular to any surface on which it acts. A vessel having flat sides and containing water. Pressure exerted by the weight of the water is perpendicular to the walls of the container. If pressure is exerted in any other direction, the water would begin to move downward along the sides and rise at the center

Question 9

Principles of pressure
Second principle

Answer 9

Fluid pressure at a point in fluid at rest is the same intensity in all directions. This principle is used in hydrostatic testing

Question 10

Principles of pressure
Third principle

Answer 10

Pressure applied to a confined fluid is transmitted equally in all directions. Illustrated by a hollow sphere around its circumference. All gauges will register the same pressure, providing that they are on the same grade line with no change to elevation

Question 11

Principles of pressure
Fourth principle

Answer 11

The pressure of a liquid in an open vessel is proportional to its depth. Illustrated by 3 containers with the same size base but have different heights. First container being a foot tall is only half the amount of psi than the second container which is 2’ and the third container being 3’ tall and being 3 times the psi of the first container.

Question 12

Principles of pressure
Fifth principle

Answer 12

The pressure of a liquid in an open vessel is proportional to the density of the liquid. Illustrated by two containers, one holding mercury (1” deep) and the other holds water (13.55” deep) but yet the pressure at the bottom of the containers are approximately the same.

Question 13

Types of principles
Sixth principle

Answer 13

The pressure of a liquid at the bottom of a vessel is independent of the shape of the vessel. Illustrated by observing water in several different shaped containers, each having the same cross-sectional area at the bottom and the same height. The pressure is the same in each container

Question 14

What is atmospheric pressure at sea level?

Answer 14

14.7 psi

Question 15

Vacuum

Answer 15

In the fire and emergency services, a pressure that is somewhat less than atmospheric pressure; a vacuum is needed to facilitate drafting of water from a static source.

Question 16

Head

Answer 16

Alternate term for pressure, especially pressure due to elevation. For every 1-foot increase in elevation, 0.434 psi is gained. Also known as head pressure

Question 17

To convert head in feet to head pressure, you must divide the number of feet by?

Answer 17

2.304

Question 18

Static pressure

Answer 18

Static pressure is stored potential energy available to force water through pipes, fittings, hose, and adapters. Static means at rest, or without motion.

Question 19

Normal operating pressure

Answer 19

The pressure found in a water distribution system during normal consumption demands is considered the normal operating pressure.

Question 20

Residual pressure

Answer 20

Pressure at the test hydrant while water is flowing; represents the pressure remaining in the water supply system while the test water is flowing and is that part of the total pressure that is not used to overcome friction or gravity while forcing water through fire hose, pipe, fittings and adapters.

Question 21

Flow pressure

Answer 21

While water is flowing from a discharge opening, the forward velocity pressure is considered flow pressure. Use of a pilot tube and gauge to measure the forward velocity of flow pressure. Firefighters can also calculate the water flowing if the size of discharge opening is known.

Question 22

Elevation

Answer 22

Height of a point above sea level or some other reference point

Question 23

Altitude

Answer 23

Geographic position of a location or object in relation to the sea level. The location may be above, below, or at sea level.

Question 24

Elevation pressure

Answer 24

Gain or loss of pressure in a hoseline due to a change in elevation. Also known as elevation loss.

Question 25

Difference between elevation and altitude

Answer 25

Elevation refers to the center line of the pump or bottom of a static water supply source above or below ground level. Altitude is the position of an object in relation to sea level.

Question 26

Friction loss

Answer 26

Loss of the pressure created by the turbulence of water moving against the interior walls of the hose or pipe

Question 27

Principles of friction loss
First principle

Answer 27

If all other conditions are the same, friction loss varies directly with the length of the hose or pipe.

Question 28

Principles of friction loss
Second principle

Answer 28

When hoses are. The same size, friction loss varies approximately with the square of the increase in velocity of the flow. (Basically by doubling or tripling the water flow through a hose or pipe increases friction loss significantly)

Question 29

Principles of friction loss
Third principle

Answer 29

For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose. The wider diameter of a hose the less friction loss their will be

Question 30

Principles of friction loss
Fourth principle

Answer 30

For a given velocity, friction loss is approximately the same, regardless of the pressure on the water.

Question 31

Water hammer

Answer 31

Force created by the rapid deceleration of water; causes a violent increase in pressure that can be powerful enough to rupture piping or damage fixtures. Generally results from closing a valve or nozzle too quickly

Question 32

Direct pumping systems

Answer 32

Uses one or more pumps that take water from the primary source and discharges it through the filtration and treatment processes. From there, a series of pumps force the water into the distribution system

Question 33

Gravity system

Answer 33

Uses a primary water source located at a higher elevation than the distribution system. The gravity flow from the higher elevation provides the water pressure.

Question 34

Combination system

Answer 34

Most communities use a combination of the direct pumping and gravity systems

Question 35

Distribution systems

Answer 35

Part of an overall water supply system that receives the water from the pumping station and delivers it throughout the area to be served

Question 36

Grid system

Answer 36

Water supply system that utilizes lateral feeders for improved distribution.

Question 37

Primary feeders

Answer 37

Large pipes (mains), with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains

Question 38

Secondary feeders

Answer 38

Network of intermediate sized pipes that reinforce the grid within the various loops of the primary feeder system and aid the concentration of the required fire flow at any point

Question 39

Distributors

Answer 39

Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers

Question 40

Indicating valves

Answer 40

Visually shows whether the gate or valve seat is open, closed, or partially closed

Question 41

Post indicator valve (PIV)

Answer 41

Type of valve used to control underground water mains found on the supply main of installed fire protection systems. The operating stem of the valve extends above ground through a “post,” and a visual means is provided at the top of the post for indicating “open” or “shut”.

Commonly used on private water supplies

Question 42

Outside screw & yoke valve (OS&Y)

Answer 42

A type of control valve for a sprinkler system in which the position of the center screw indicates whether the valve is open or closed. Also known as outside stem and yoke valve

Question 43

Non-indicatingvalves

Answer 43

Most common type of valves used on most public water distribution systems. These valves have no indication other than water flow that tells you that if the valve is open or closed

Question 44

This is the average amount of water used per day based on the total amount of water used in a water distribution system over the period of one year?

Answer 44

Average daily consumption (ADC)

Question 45

This is the maximum total amount of water that was used during any 24-hour interval within a 3-year period. Unusual situation, such as refilling a reservoir after cleaning, should not be considered in determining the maximum daily consumption

Answer 45

Maximum daily consumption (MDC)

Question 46

This is the maximum amount of water used in any 1 hour interval over the course of a day

Answer 46

Peak hourly consumption (PHC)