Chapter 6 What is Water and Where Does it Come From

Six principles of pressure

1) Fluid Pressures is perpendicular to any on which acts. 2) fluid pressure at a point in a fluid at rest is the same intensity and all directions. 3) pressure applied to a confined fluid from with out is transmitted equally in all directions. 4) pressure of a liquid in is proportional to its depth 5) The pressure of a liquid in an open vessel is proportional to the density of the liquid 6) The pressure of a liquid on the bottom of a vessel is independent of the shape of the vessel.

What is the atmospheric pressure at sea level(Standard atmospheric pressure)

14.7 psi

How high of a water column do you need to create 1 psi

2.304 = 1 cu/ft water is 62.4 lbs 1ft squared is 144 in (12x12) 62.4 / 144 = .0434 1 (original height of cu/ft) / .434 = 2.304 Pg 141 (171)

How much PSI is required to reduce the volume of water by 1%

30,000

How much does one cubic foot of water weigh

62.4 pounds

How much does a cubic foot of water weigh

62.5 lbs

How many gallons of water are in one cubic ft of water

7.48

Recommended size for fire hydrant supply lines in business and industrial districts

8 inches cross connecting every 600 feet. 12 inch mains maybe used not, cross connecting at frequent intervals, as large as 48 inches

How much does a gallon of water weigh

8.33 pounds

How much BTU's does 1 pound of water require to convert it to steam

970 Btu 1023 kJ

Grid system

A distribution system that provides circulating feed from several mains

Specific heat

A measure of the heat absorbing capacity of a substance

Joule

A unit of the work. 1 calorie = 4.19 joules

Perfect vacuum

Absolute zero pressure

What is a vacuum

Any pressure less then Atmospheric pressure

The recommended size for fire hydrant supply mains in residential areas

At least 6" with 8 inches cross connecting mains at intervals of no more than 600 feet

Definition of static

At rest or without motion

A fire hydrant that receives water from two or more directions

Circulating feed, or looped line

Types of water treatment

Coagulation, sedimentation, filtration, the addition of chemicals, bacteria, or other organisms,

Two ways that water extinguishes

Cooling, or absorbing heat from the fire. Smothering, excluding oxygen.

Above sea level atmospheric pressure

Decreases approximately .5 psi for every 1000 feet

Why is latent heat of vaporization significant in firefighting

Definition on page 137 For 1 gallon of water at 60°F it requires 152 (212-60=152) Btu to raise each pound of water to 212°F. So 1 gallon of water absorbs 1266 ( 152 x 8.33= 1266) BTU getting to 212°F. Water weighs 8.33 pounds. So 1 pound of water requires 970 Btu to turn to steam. So 1 gallon of water absorbs 1266 Btu plus an additional 970 Btu per lb, 8080 ( 970 x 8.33= 8080) BTU, for a total of 9346 Btu to convert to steam.

Three means of moving water

Direct pumping system. Gravity system. Combination system.

Head pressure

Divide the number of feet above the discharge orifice by 2.304 ( The number of feet that one psi will raise a 1 in.² column of water)

Flow pressure

Foward velocity pressure at a discharge opening while water is flowing

Types of control valves in water distribution systems

Gate valves, butterfly valves

Head

Height of the water supply above the discharge orifice

Critical velocity

If the velocity is increased beyond practical limits the friction becomes so great that the entire stream is agitated by resistance

Four principles of friction loss

Length of hose or pipe. Friction loss varies approximately with the square of the increase in the velocity . Friction loss varies inversely as the fifth power of the diameter of the hose. For a given flow velocity, friction loss is approximately the same, regardless of the pressure on the water.

Most flammable liquids have a specific gravity of

Less than one

Maximum daily consumption

Maximum total amount of water that is used during any 24 hour interval within a three-year period

Water is heaviest when? Water is lightest when?

Near it's freezing point. Near its boiling point.

How is water density measured

Pounds per cubic foot

psia

Pounds per square inch absolute ( aka, the psi above a perfect vacuum, absolute zero )

psig

Pounds per square inch gauge

The hierarchy of a grid system

Primary feeders, (Large pipes) Secondary feeders ( intermediate 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 given point), Distributors (Great arrangements of smaller mains serving individual fire hydrants and blocks of consumers

Elevation

Refers to the level of the pump or the bottom of the static water supply above or below ground level

Definition of residual

Remainder or that which is left

Force

Simple measure of weight, usually expresses in pounds or kilograms

Static pressure

Stored potential energy available to force water through pipe, fittings, firehose, and adapters

Friction loss

That part of the total pressure loss while forcing water through pipe, fittings, firehouse, and adapters.

BTU

The amount of heat required to raise the temperature of 1 pound of water 1°F

Average daily consumption

The average of the total amount of water used in a water distribution system over the period of one year

Specific gravity

The density of liquids in relation to water. Liquids with a specific gravity less than one hour later than water and therefore will float in water. A Specific gravity that is greater than one are heavier and will sink in water.

Pressre

The force ER unit area exerted by a liquid or gas measured in pounds per square inch, psi, pounds per square foot, psf, or kilopascals, kPa

The difference between static pressure and normal operating pressure

The friction caused by water flowing through pipes, valves and fittings.

What is the difference between static pressure and normal operating pressure

The friction caused by water flowing through various pipes, valves, and fittings in the system.

Elevation pressure

The loss or gain that is occurred because of gravity

Peak hourly consumption

The maximum amount of water used in any one hour interval over the course of a day

Specific heat

The measure of heat absorbing capacity of a substance

Residual pressure

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

Altitude

The position of an object above or below sea level

Normal operating pressure

The pressure found in a water distribution system during normal consumption demands

Latent heat of vaporization

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

How the specific heat of a substance is determined

The ratio between the amount of heat needed to raise the temperature of a specific 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

Coefficient of friction

The rougher the inner lining of the pipe the greater the friction loss will be

What are the fundamental components of a water system

The source. Means of moving water. Water processing or treatment facilities. Water distribution systems, including storage.

Velocity

The speed at which fluid travels

Boiling point

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

Viscosity

The tendency of a liquid to possess internal resistance to flow.

How to determine the amount of water that a community needs

Total amount of water needed for domestic and industrial use and for firefighting use

Who are the experts in water supply problems

Water department officials

Calorie

quantity of heat required to raise the temperature of 1 gram of water by 1°C at 1 atmosphere pressure.