ifsta Chapter 5 Flashcards
Water is considered to be
) incompressible
Water can be used to smother fires in what kind of combustible liquids?
Those with a specific gravity higher than 1
What principle of water makes it somewhat difficult to soak into dense material?
Its high surface tension
Water has the ability to extinguish fire in several ways
It can cool or absorb
heat from the fire, as well as smother (exclude oxygen from) fires
The term force is a simple measure of weight that is expressed in what unit of measurement:
pounds or Newtons.
The term pressure may have a variety of meanings. In this manual, pressure is defined as force per unit area and or?
Pressure may be expressed as pounds per square foot (psf), pounds per square inch (psi), or kilopascals (kPa).
The weight of 1 cubic foot of water
62.4lbs
A 1-inch square column of water 1 foot high therefore exerts a pressure at its base
0.434
a column of water 2.304 feet high exerts pressure of
1psi
The speed at which a fluid travels through a hose or pipe is determined by the pressure upon that fluid as well as the size of the orifice through which it is flowing.
velocity
Atmospheric pressure that surrounds the earth is
depth and density, exerting pressure on everything. This pressure is greatest at low altitudes and least at very high altitudes.
Atmospheric pressure is commonly measured using what substance
mercury
how many times denser is mercury compared to water?
mercury is 13.55 times denser than water
In the fire and emergency services, a pressure that is somewhat less than atmospheric pressure;
vacuum
the height of a water supply above the discharge orifice
Head
The water flow definition of ________________________________ is stored potential energy avail-able to force water through pipes, fittings, hose, and adapters.
Static Pressure
_________ is the portion of the total available pressure not used to overcome friction loss or gravity while forcing water through pipes, fittings, hoses, or adapters.
Residual Pressure
__________refers to the center line of the pump or the bottom of a static water supply source above or below ground level. fire and rescue term
Elevation
The pressure losses or gains due to gravity _______
Elevation Pressure or also known Elevation Loss
Loss of pressure created by the turbulence of water moving against the interior walls of the hose or pipe.
Friction Loss
_________ has a smoother inner lining and causes less friction loss than _________.
Modern fire hose, and Older Hose
The friction loss in older hose may be as much as ___________ than that of new hose.
50 percent greater
First Principle of Friction Loss
If all other conditions are the same, friction loss varies directly with the length of the hose or pipe.
Second Principle of Friction Loss and how does it work?
When hoses are the same size, friction loss varies approximately with the square of the increase in the velocity of the flow.
(As the flow doubles, the friction loss increases four times)
(As the flow triples, friction loss increases nine times )
Third Principle of Friction Loss and explain?
For the same discharge, friction loss varies inversely as the fifth power of the diameter of the hose.
When the flow remains constant, the friction loss in a hose will decrease
when the diameter of the hose is increased.
Fourth Principle of Friction Loss
For a given velocity, friction loss is approximately the same, regardless of the pressure on the water.
Flow pressure will always be greatest near the source of supply and lowest at the farthest point in the system.
Three characteristics of Reducing Friction Loss
Hose Length, Hose Diameter, sharp bends (Kinks) in the hose
water hammer
Suddenly stopping water, moving through a hose or pipe, results in an energy surge being transmitted in the opposite direction,
Sources of Water Supply
Surface water (lakes, Rivers), and Ground Water (water wells or water-producing springs)
There are three methods of moving water in a system
Direct pumping system, Gravity System, Combination system
Uses one or more pumps that takes water from the primary source and discharges it through the filtration and treatment processes.
Direct Pumping System
Uses a primary water source located at a higher elevation than the distribution system.
Gravity System
Most communities use a combination of the direct pumping and gravity systems.
Combination system
what is the most common example of gravity fed primary water source?
reservoir at a higher elevation
The ________________ of the overall water supply system receives the water from the pumping station and delivers it throughout the area served.
Distribution system
A fire hydrant that receives 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, Distributors
Large pipes (mains), with relatively widespread spac-ing, 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
Valves should be inspected and operated yearly by the
Water utility or Authority
Indicating valves.
visually shows whether the gate or
valve seat is open, closed, or partially closed
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.”
Post indicating Valve
PIV are many used in what water system
Private water systems
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.
OS&Y valve (outside screw and Yoke valve)
Non indicating valves.
These are the most common type of valves used on
most public water distribution systems. In a water distribution system, these are normally installed in valve boxes or manholes.
A water Key is required to use on the these valves
a Control Valve is a _________ valve
Non-indicating
Control valves are generally a
gate valve.
Private water supply systems are most commonly found on
large commercial, industrial, or institutional properties, but may also be found in some residential developments.
the private water supply system exists for one of the three following purposes:
- To provide water strictly for fire protection purposes
- To provide water for sanitary and fire protection purposes
- To provide water for fire protection and manufacturing processes
