Chapter 5 - Principles of Water Flashcards
For fire protection purposes, ordinary fresh water is considered to weigh ______ or _____.
- 4 lb/cu ft
8. 3 lb/gal
At ____, water converted to steam occupies approximately ____ times its original volume.
212*F
1,700
The speed at which fluid travels through a hose or pipe is determined by the _______ upon that fluid as well as the ____ of the orifice through which it is flowing
Pressure
Size
First Principle of Water
Fluid pressure is perpendicular to any surface on which it acts
Second Principle of Water
Fluid pressure at a point in fluid at rest is the same intensity in all directions
Third Principle of Water
Pressure applied to a confined fluid is transmitted equally in all directions.
Fourth Principle of Water
The pressure on a liquid in an open vessel is proportional to its depth.
Fifth Principle of Water
The pressure of a liquid in an open vessel is proportional to the density of the liquid
Sixth Principle of Water
The pressure of a liquid at the bottom of a vessel is independent of the shape of the vessel.
Atmospheric pressure at sea level is ___ psi, which is considered standard atmospheric pressure.
14.7 psi
Any pressure less than atmospheric pressure is called _____, and absolute zero pressure is called a _____________.
Vacuum
Perfect Vacuum
In the fire service, ____ refers to the height of a water supply above the discharge orifice.
Head
To convert head in feet to head pressure, you must divide the number of feet by _____ (the number of feet that 1 psi will raise one square in column of water).
2.304
The water flow definition or ________ is stored potential energy available to force water through pipes, fittings, hose, and adapters
Static Pressure
For every 1-foot increase in elevation, ______ psi is gained.
0.434 psi
The difference between static pressure and normal operating pressure is ________.
The friction caused by water flowing though the pipes, valves, and fittings of the system.
_________ is the portion of the total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, hoses, or adapter.
Residual Pressure
While water is flwoing from a discharge opening, the forward velocity pressure is considered _________.
Flow Pressure.
_________ refers to the center line of the bump or the bottom of a static water supply source above or below ground level. _______ is the position of an object in relation to sea level.
Elevation
Altitude
The pressure losses or gains due to gravity are called ____________.
Elevation pressure
Above sea level, atmospheric pressure decreases approximately ___ psi for every ____ feet.
0.5 psi
1,000 feet
The fire service definition of ____________ is that part of the total pressure lost while forcing water through piping, fittings, fire hose, and adapters.
Friction Loss
The following causes friction loss in a fire hose:
> Movement of water molecules against each other.
Linings of fire hose/delaminating hose
Couplings
Sharp bends/kinks
Change in hose size or orifice by adapters
Improper gasket size
First Principle of Friction Loss
If all other conditions are the same, friction loss caries directly with the length of the hose or pipe.
Second Principle of Friction Loss
When hoses are the same size, friction loss varies approximately with the square of the increase in the velocity of the flow.
(e.g.)
flow of 200 to 400 gpm (2^2 = 4)
3.2psi @ 200gpm = 12.8psi ub 400gpm. (3.2 x 4 = 12.8)
Third Principle of Friction Loss
For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose.
(e. g.)
(2. 5)^5/3^5 = 97.66/243 = 0.4 that of the 2.5 inch. Therefore, the 3-inch hose has 60% less friction loss than the 2.5-inch hose.
Fourth Principle of Friction Loss
For a given velocity, friction loss is approximately the same, regardless of the pressure on the water.
With water being virtually incompressible, a pressure of _____ psi is required to reduce it volume ___ percent.
30,000 psi
1%
There are three methods of moving water in a system.
> Direct Pumping System
Gravity System
Combination System
A fire hydrant that received water from only one direction is known as a __________.
Dead-End Hydrant
A grid system should consist of the following components:
> Primary Feeders
Secondary Feeders
Distributor
Large pipes, with relatively widespread spacing, that convey large quantities of water to various points of the system for local distribution to the smaller mains.
Primary Feeders
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.
Secondary Feeders
Grid arrangement of smaller mains serving individual fire hydrants and blocks of consumers.
Distributors
The ___________ 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.
Average Daily Consumption (ADC)
The ____________ is the maximum total amount of water that was used during any 24-hour interval within a 3-year period.
Maximum Daily Consumption (MDC)
The ____________ is the maximum amount of water used in an 1-hour interval over the course of a day.
Peak Hourly Consumption (PHC)
