Presentation on theme: "For The Driver Operator"— Presentation transcript:
1 For The Driver Operator Field HydraulicsFor The Driver Operator
2 HydraulicsTheory and application allowing control and use of fluid pressure
3 Hydraulic TheoriesUnderstanding the theoretical and practical application of hydraulics essential for pump operation. The study of fire ground hydraulics is divided into two categories, theoretical and rule of thumb. The driver/operator must be able to apply both.
4 Elements of Hydraulic Calculation Nozzle LossAttack Line LossElevation LossManifold/ ApplianceStandpipe LossSupply Line Loss
5 Terminology in Friction Loss Formulas NP - Nozzle PressureFL Friction LossAL - Appliance LossEL - Elevation PressureTPL - Total Pressure LossNPDP - Net Pump Discharge Pressure
6 TheoreticalIn the classroom and non-emergency activities of the fire department, mathematical equations are used to calculate the flow characteristics of our equipment and systems. This method of calculation is commonly referred to as “Theoretical Hydraulics”. By using mathematical formulas, a relatively accurate calculation of the total probable friction loss is obtained. This method is normally more accurate than Rule of Thumb.
7 Theoretical FormulaThere are many formulas and methods for figuring friction loss but the Renton Fire Department has adopted the following for use in its training program.FL = CQ2LWhereQ = QuantityC = CoefficientL = Length in 100’s
8 Hose Coefficients Coefficients for Renton Fire Department hose:
9 Siamesed Hose Lines Coefficients Two 2 ½”Three 2 ½”
10 Rule of ThumbOn the fire ground, the driver/operator normally works with a condensed and simplified application known as “Rule of Thumb Hydraulics”. Rule of thumb hydraulic formulas are a chosen series of fixed, rounded values that can be applied to an operation sequentially to build a water delivery system.
12 Appliance Pressure Loss < 350 gpm no calculated loss> 350 gpm 10 psi per appliance25 psi for all master stream devices25 psi for all standpipes
13 Nozzles and Tips Types of Nozzles Broken Stream Solid Stream Periphery Deflected(Combination )Impinging stream (Naval type)
14 Nozzle Design Restriction The purpose of any nozzle is to provide a restriction ofthe flow to build pressure. This restriction, and subsequentcreated pressure, provides a usable velocity to project thewater stream. For any one flow, there is one correct nozzlesize (restriction) to develop the optimum pressure andvelocity.Restriction
15 Designed Nozzle Pressure Smooth Bore Nozzle - Hand line PSI½” thru 1 ¼” nozzlesSmooth Bore Nozzle - Master Stream PSInozzles 1 ¼” and overFog Nozzle PSIall nozzlesPump Pressure
16 Solid Stream - Characteristics The mechanical characteristics of a solid stream nozzle produce a compact stream that has a higher mass and velocity. These features typically yield better reach and penetration.
17 Solid Stream - Composition The interior diameter of the nozzle is gradually decreased until it reaches a point just short of the outlet. At this point the straight cylindrical bore has a length from 1 to 1 ½ times its bore, this area is known as the stream shaper
18 Solid Stream Mechanics Water flowing through a nozzle is subject to the same physical principals of friction as hose. The net effect of friction in a solid stream nozzle is the creation of a laminar flow. The center of the flowing stream is faster than the edge. This creates a peripheral turbulence that is visible after the stream exits the nozzle.
19 Solid Stream - Formulas Discharge Volume:29.7 x D2 x NPNozzle Reaction:1.57 x D2 x NP
20 Fog Stream - Characteristics A stream of water remains in a solid mass, not losing continuity until it strikes an object, is overcome by gravity or is changed by friction with the air. Fog stream nozzles are designed around this theory and are commonly called broken stream appliances
21 Fog Stream - Composition All fog streams are of two mechanical types, Periphery-deflected or impinging stream. The shape and reach of a fog stream are results of the appliance shape and the velocity/pressure of the water.
22 Impinging StreamImpinging Stream fog patterns are produced by driving jets of water together at a set angle to break the streams into finely divided particles. These appliances generally produce wide angle fog patterns.
23 Periphery-DeflectedPeriphery –Deflected streams are produced by deflecting water from the periphery of an inside circular stem to the inner circumference of the adjustable barrel. The position of the barrel varies the shape of the stream from a light fog to a straight stream. There are two common types of these nozzles, automatic and non-automatic.
24 Periphery-Deflected, Automatic Automatic Periphery-Deflected nozzles have a spring loaded baffle assembly that reacts to incoming pressure. The baffle is calibrated to function at 100 PSI. The model illustrated has a sliding valve which allow the firefighter to meter the flow at the nozzle.
25 Periphery-Deflected, Automatic When pressure at the nozzle is less, the baffle moves in to maintain the pattern. When the pressure is greater than 100 PSI the baffle moves out to allow more volume and minimize the nozzle reaction.
26 Periphery-Deflected, Automatic Task Force Tip nozzles have a slide valve assembly that allows the water flow at the tip to be metered. By using this valve design, the nozzle has a smoother flow and less turbulence. Note the valve position in the illustrations.
30 Nozzle ReactionNozzle reaction is the force that a firefighter feels when he is operating a nozzle. Nozzle reaction is primarily a result of discharge pressure at the nozzle. If the nozzle pressure is lowered, the firefighter will note a corresponding decrease in the nozzle reaction.
31 Nozzle Reaction To calculate the nozzle reaction use the following formulas, note same flows can often be developed at a far lower nozzle reaction in solid stream nozzles. Traditional thought is that solid bore hand lines should be pumped at 50 psi. Any nozzle pressures higher than 65 psi becomes unmanageable. In the following table review and compare the reaction force of various fire streams.Nozzle Reaction: Solid Stream1.57 x D2 x NPNozzle Reaction: Fog Streamx Q x NP
50 Answer 100 psi NP @ 150 gpm 124 psi FL 1 ¾”, 200’ 34.72 psi EL (.434 psi X 8 floors above the 1st)25 psi FL Standpipe08 psi FL Siamesed 2 ½”psi NPDPWhat single adjustment could you make to cut the friction loss by NPDP by 25 psi?
51 180 GPM 250 GPM 150’ of 2 ½” 150’ of 1 ¾” 150’ of 2 ½” 2 ea. / 100’ of 2 ½”
52 Answer 100 psi NP @ 180 gpm 75.33 psi FL 1 ¾”, 150’ 26.04 psi EL (.434 psi X 6 floors above the 1st)25 psi FL Standpipe09.25 psi FL Siamesed 2 ½”245 psi NPDPThe 2 ½” NPDP was pump to the highest friction loss. How would the excess pressure be dealt with in this line?