Chpt 7 Flashcards
Fire service _______ is the study of the characteristics and movement of water as they pertain to calculations for fire streams and fire ground operations
Hydraulics
The scientific or more exact calculations are commonly referred to as
Theoretical hydraulics
Is the term for the less exact but certainly more user friendly and forgiving calculation methods used on the fire ground
Fireground hydraulics
To be as accurate as possible when performing hydraulic calculations, you should use the manufactures recommended ________specific to the actual used on your hose or appliance, with your fire apparatus under the guidelines of your fire department
Nozzle pressure
Flow tests with your equipment will confirm the most precise _____ to use
Pressures
Fighting fire with water is a matter of ______ versus heat generation, British thermal units, joules, or kilocalories
Flow rate
To extinguish a fire, sufficient flow must be applied to over come the heat generated by the fire a rate referred to as the _______
Critical rate of flow
The real goal of the driver operator is to deliver the correct ______ to the nozzle
Flow
The ______ is the total pressure needed to overcome all friction, appliance, and elevation loss while maintaining adequate nozzle pressure to deliver effective fire streams
PDP
PDP equation
PDP = NP + FL
Is the pressure required at the nozzle to deliver the fire stream and flow rate for which the nozzle was designed
Nozzle pressure
Smooth bore nozzles on a handline are normally flowed at a NP of _____.
50 psi
Some master stream smooth bore nozzles are rated less than
80 psi
Fog nozzles are generally rated at
100 psi
Three standard nozzle pressures, all of which are dictated by the type and the use of the nozzle, are generally sufficient for most fire ground operations
70 psi for all fog nozzles
50 psi for smooth bore handline nozzles
80 psi for smooth bore master stream nozzles
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.
Newton third law of motion
Is the opposing reaction that occurs as water is expelled from the nozzle or the force that pushes back on the firefighter when he or she flows water
Nozzle reaction
Calculating nozzle reaction should not be attempted at the fire scene but rather determined during
Training sessions
To calculate nozzle reaction in a smooth bore use the formula
NR = 1.5 x d2x np
To calculate nozzle reaction in a fog nozzle use the formula
NR= 0.0504 x gpm x NP
Is the volume of water moving through the nozzle during a specific time period; it is measured in units or gpms
Flow rate
Is the pressure lost from turbulence as water passes through pipes, hoses, fittings, adapters, and appliances
Friction loss
Friction loss formula
FL = C Q2 L
When flowing two identical lines that have the same nozzle pressure and flow and that are of equal size, length, and elevation, both lines require the same
Pressure
Under normal conditions you always fully open a valve to prevent excess turbulence and FL through the valve; however, partially closing a valve sometimes necessary to prevent excessive pressure from being delivered. For those discharged requiring a lesser pressure, you must open the valve just enough to deliver the desired pressure, a practiced referred to as
Gating the valve
Calculations must be adjusted for the distance the nozzle is above or below the pump, which is referred to as
Elevation pressure
The pressure lost when the nozzle is above the pump is known as
Elevation loss
The pressure gained when the nozzle is below the pump is known as
Elevation gain
EP could be _____ if the nozzle and the pump are at the same elevation
Zero
Water exerts a pressure of _____ psi per 1 foot of water column
0.434 psi
A common application for this rule would be ____ per gain or loss for each floor of elevation change in a residential structure where floor spacing is commonly 10 ft
5 psi
Are devices that are used to connect and adapt hoses, and to direct and control water flow in various hose layouts
Appliances
Generally, the appliance FL is considered insignificant and maybe recorded as zero when water flows are less than
350 gpms
Allow ____ FL in appliances when the flow rate is 350 gpm or greater
10 psi
Allow ____ FL for all master stream appliances
25 psi
Fire streams of less than 350 gpm are generally considered
Handlines
Whereas fire streams of 350 gpm or greater are considered
Master streams
In your calculations, you should assume _____ of appliance loss for master streams and _____ of AL for handlines with a flow of 350 gpm or greater
25 psi
10 psi
Total pressure loss equation
TPL = (cxq2xL) + AL + EP
A _____ is a device that allows multiple hoselines to converge into one hoseline
Siamese connection
A _____ is used by fire departments that do not have large diameter hose and need to supply large amounts of water at a reasonable amount of pump pressure
Siamese connection
Portable master stream devices such as a removable deck gun and the inlet of aerial water ways on squirts, quints, and ladder trucks may be supplied by a single LDH supply or a _____
Siamese connection
The fire department connection on buildings with standpipe sprinkler systems will have a Siamese connection consisting of two _____ connections or one LDH
2 1/2 inch connections
The three methods used to calculate the FL in the lines to the Siamese connections when the lines are of equal size and length are the ______
Split flow method
Coefficient method
Percentage method
The term ______ refers to an aerial fire apparatus with a fixed water way attached to the underside of the ladder such that a water inlet at the base supplies a master stream device at the end
Prepiped elevated master stream
The master stream device may have a ______ that places the nozzle on the bed section for rescue or on the fly section for water tower operations
Locking mechanism
Unless the loss in the intake, piping, and nozzle has been established for the specific apparatus, you should assume a minimum of ______ FL for all master streams
25 psi FL
It is extremely beneficial to predetermine pump discharge pressure for high rise structures to limit the amount of calculations needed on the fireground during excitement of an actual incident.as a general rule, you should not exceed a PDP of _____ unless you know the system is designed to handle the greater pressure required
200 psi
The one pressure that you control from the pump panel is the ______ needed at any one discharge (regardless of the floor it’s on)
Highest pressure
Any lower pressures needed at subsequent discharges will have to be controlled by a firefighter staged at the discharge valve of the _____ used
Standpipe riser
A _____ is the vertical portion of the system piping within a building that delivers the water supply for fire hose connections, and sprinklers on combined systems, vertically from floor to floor.
Standpipe riser
The use of the _______ will compensate for any discrepancies if calculations are off or circumstances have changed
In line gauge
Use of an ____ is highly advantageous for standpipe operations
In line gauge
If no preincident plan exists and the size of the riser is unknown, then it’s too late to try and measure this riser. Instead simply add ____ to account for stand pipe riser
25 psi
Are installed on standpipe risers where static pressures exceed 175 psi per NFPA 13 standard for the installation of sprinkler systems.
Pressure regulating valves
The height of a column of water above the discharge is known as
Head
The pressure in that column of water is referred to as
Head pressure
To determine head pressure, divide the height of the column in feet by ______
2.304
Static sources such as lakes and streams require establishing a
Draft
Dynamic sources such as hydrants or another fire apparatus are
Positive pressure sources
Is the amount of pressure created by the pump after it receives water under pressure from a hydrant or another pump
Net pump discharge pressure NPDP
Are more exact, generally require more mathematical skills, and take more time to compute.
Theoretical hydraulic calculations
May be used on the fireground or for preincident planning purposes, such as determining the appropriate pump pressures for high risk or high hazard targets as well as buildings requiring complex hose layouts and standpipe systems
Theoretical hydraulic calculations
Employ methods intended to estimate calculations more quickly due to the urgency of the incident
Fire ground hydraulics
Firefighters often create a ___ of typical handline and master stream calculations for the hoses, nozzles, and devices specific to the fire apparatus within their department
Chart
The _____ may consist of a sliding card or a slide rule
Manual hydraulic calculator
Mounted calculators are seldom encountered today, where as the ______ type is quite common
Hand held type
The hand held pocket size ________ allows you to calculate engine pressure, FL, application rate, and reaction force also know as normal reaction.
Electronic calculator
The purpose of the _____ is to quickly determine the amount of FL per 100 ft
Hand method
The ______ method determines FL in 21/2 in hose only and for flows of 160 gpms or greater
Subtract 10 method
The ______ is a quick method calculating FL per 100 ft in 3 in. to 5in hoseline only. It is especially useful when the apparatus is part of the relay operation and is supplying another pumper.
Condensed Q method
Because most fire departments use a supply line with a diameter in the range of 3 in to 5 in, the ______ is a quick and easy way to determine the PDP
Condensed Q method
When developing a suppression strategy, there is no more useful tool than knowledge of the target structure and a well developed
Preincident plan
To calculate the available water from a hydrant, use the
First digit method
Fire service hydraulic calculations are used to determine the required _______ for fireground operations
Pump discharge pressure PDP
The major variables are the many numerical values influencing
Calculations
As the driver/operator, you must combine your knowledge of the specific equipment on your fire apparatus with the methodology underlying _____
Hydraulic theory
Combination nozzles (fog nozzles) traditionally have a NP of _____ but come with different features that have varied NP levels.
100 psi
Low pressure fog nozzles have a NP that varies from
50 to 75 psi
Unless manufacturers instructions vary, limit nozzle pressure for smooth bore nozzles on elevated master streams to a maximum of
80 psi
This calculation works for fog nozzles that are operating in a straight stream pattern only
NR= 0.0504 X GPM X NP
Fog nozzles are designed with predetermined flow rates based on a set
NP
Nozzle reactions for smooth bore nozzle and fog nozzles can be calculated, with each reaction expressed in terms of the _____ that the firefighter must overcome to control the nozzle
Pounds per force
If you exceed 50 psi of FL per 100 ft of hose, then the flow may begin to decrease either from the increasing turbulence in the hose or from a reduction in the pump capacity owing to excessive
PDP
In any pumping scenario, if appliances are used or elevation gain or loss is present, you must insert ________ into the FL formula
AL and EP appliance loss or elevation pressure
A _____ is used to split a single line into two lines
Wye
On the discharge side of the pump, this device may be used to bring two or three lines into one attack line, thereby reducing the FL in a long reach.
Siamese
In the _______ , you divide the flow among the equally and calculate the pressure to supply one line because that pressure will support all lines.
Split flow method
The ______ utilizes the fl equation with the appropriate coefficient for the lines entering the Siamese connection
Coefficient method
In the _______, you calculate the total flow through one line.
Percentage method
The FL in two hoselines will be 25 percent of the total flow through one hoseline, and the fl in three hoselines will be approximately 10 percent of the total flow through one hoseline.
Percentage method
No single FL amount can be identified that will adequately encompass all prepiped elevated master streams devices; therefore it is imperative that each aerial device be tested for its unique amount of
FL friction loss
In multistory buildings, the attack lines should be supplied from the floor below with an _______ on the standpipe outlet
In line gauge
You may boost the pressure to the maximum design pressure; however, if calculations require a pressure lower than the system minimum, default to the design pressure so that the ______ can operate properly
PRV pressure reducing valve
On the fireground, ________ are performed mentally
Theoretical calculations
200 ft of 2 1/2 in hose with a 1 1/4 inch solid tip may require a pressure of _____ to achieve desired flow
90 psi
Hydraulic calculators may be either
Manual or electronic
______ offer a fire stream calculator on one side and a FL calculator on the other side
Slide rule hydraulic calculators
Electronic calculators may be either
Mounted or hand held
The hand method for 2 1/2 in hose works so nicely because the coefficient for 2 1/2 in hose is ____ when using imperial units
2
The simplicity of this method is its strength; using this technique, you can determine FL in 2 1/2 in hose very quickly.
Subtract 10 method
