PUMPS, VALVES, PUMPS, VALVES, & FANS& FANS

……Moving fluidsMoving fluids

ObjectivesObjectives

•• Comprehend the basic construction and Comprehend the basic construction and application of valves usedapplication of valves used

•• Comprehend the basic operation and Comprehend the basic operation and application of different pumpsapplication of different pumps

•• Know BernoulliKnow Bernoulli’’s principle, the concept s principle, the concept of pressure, & Net Positive Suction Headof pressure, & Net Positive Suction Head

•• Be familiar with operation and Be familiar with operation and application of centrifugal & axial fansapplication of centrifugal & axial fans

ValvesValves

•• DefDef’’n: devices which control the amount and n: devices which control the amount and direction of fluid flow in piping systemsdirection of fluid flow in piping systems

•• Typically made of bronze, brass, iron, or steel Typically made of bronze, brass, iron, or steel alloyalloy

•• Components:Components:

-- Valve bodyValve body -- PackingPacking-- DiscDisc -- Packing gland/nutPacking gland/nut

-- SeatSeat -- StemStem-- BonnetBonnet -- Wheel Wheel

Types of ValvesTypes of Valves•• Two basic groups:Two basic groups:

•• Stop valves Stop valves -- used to shut off or partially shut used to shut off or partially shut off the flow of fluid ( ex: globe, gate, plug, off the flow of fluid ( ex: globe, gate, plug, needle, butterfly)needle, butterfly)

•• Check Valves Check Valves -- used to permit flow in only one used to permit flow in only one direction (ex: balldirection (ex: ball--check, swingcheck, swing--check, liftcheck, lift--check)check)

•• Special types:Special types:•• Relief valvesRelief valves•• PressurePressure--reducing valvesreducing valves•• RemoteRemote--operated valvesoperated valves

Stop ValvesStop Valves

•• Globe ValvesGlobe Valves•• Most common type of stop valveMost common type of stop valve

•• Used in steam, air, water, & oil linesUsed in steam, air, water, & oil lines

•• Disc attached to valve stem rests against seat Disc attached to valve stem rests against seat to shut off flow of fluidto shut off flow of fluid

•• AdvAdv: Used for throttling: Used for throttling

•• DisadvDisadv: flow resistance: flow resistance

Globe ValveGlobe Valve

Stop ValvesStop Valves

•• Gate ValvesGate Valves•• Used when there must be straightUsed when there must be straight--line flow line flow

of fluid w/ min. resistanceof fluid w/ min. resistance

•• Gate usually wedgeGate usually wedge--shaped or a vertical discshaped or a vertical disc

•• AdvAdv: No flow restrictions: No flow restrictions

•• DisadvDisadv: poor throttling: poor throttling

Gate ValveGate Valve

Stop ValvesStop Valves

•• Butterfly ValvesButterfly Valves•• Used in water, fuel, and ventilation systemsUsed in water, fuel, and ventilation systems

•• AdvAdv: small, light: small, light--weight, & quickweight, & quick--actingacting

•• DisadvDisadv: leaks early & only low: leaks early & only low--flow throttleflow throttle

•• Ball ValvesBall Valves•• Similar to butterfly valvesSimilar to butterfly valves

•• Normally found in seawater, sanitary, trim Normally found in seawater, sanitary, trim and drain, and hydraulic systemsand drain, and hydraulic systems

Butterfly ValveButterfly Valve

Check ValvesCheck Valves

•• Controls direction of flowControls direction of flow

•• Operated by flow of fluid in pipeOperated by flow of fluid in pipe

•• Types:Types:•• Swing check Swing check -- disc moves through an arcdisc moves through an arc

•• Lift check Lift check -- disc moves up and downdisc moves up and down

•• Ball check Ball check -- ball is located at end of stem and ball is located at end of stem and lifts to allow flowlifts to allow flow

SwingSwing--check Valvecheck Valve

Relief ValvesRelief Valves

•• Used to protect piping system from Used to protect piping system from excessive pressureexcessive pressure

•• Opens automatically when fluid pressure Opens automatically when fluid pressure becomes too high (pressure acts against becomes too high (pressure acts against spring pressure)spring pressure)

•• Relieving pressure set by an adjusting Relieving pressure set by an adjusting screwscrew

PressurePressure--reducing Valvesreducing Valves

•• Used to automatically provide a steady, Used to automatically provide a steady, lower pressure to a system from a higher lower pressure to a system from a higher pressure sourcepressure source

•• Used in air, lubeUsed in air, lube--oil, seawater, and other oil, seawater, and other systemssystems

RemoteRemote--operated Valvesoperated Valves

•• Valves that allow operation from distant Valves that allow operation from distant stationsstations

•• Types:Types:•• Mechanical Mechanical -- uses reach rods and gearsuses reach rods and gears•• Hydraulic Hydraulic -- uses fluid and piston set upuses fluid and piston set up•• Motor Motor -- uses and electric or pneumatic uses and electric or pneumatic

motormotor•• Solenoid Solenoid -- uses coil and core mechanism to uses coil and core mechanism to

open or close on an electric signalopen or close on an electric signal

PumpsPumps

•• DefDef’’n: device that uses and external n: device that uses and external power source to apply force to a fluid in power source to apply force to a fluid in order to move it from one place to order to move it from one place to anotheranother

•• Must overcome:Must overcome:•• (1) frictional forces from large quantities of (1) frictional forces from large quantities of

fluidfluid•• (2) difference in static pressure between two (2) difference in static pressure between two

locationslocations

•• Must provide any velocity desired Must provide any velocity desired

Pumps Pumps –– BernoulliBernoulli’’s Theorems Theorem•• Pressure head: measure of fluidPressure head: measure of fluid’’s mech. PEs mech. PE•• Velocity head: measure of fluidVelocity head: measure of fluid’’s mech. KEs mech. KE•• Friction head: measure of energy lost that heats fluid Friction head: measure of energy lost that heats fluid

ZZ11 + P+ P11//ρρ + V+ V1122/2g = Z/2g = Z22 + P+ P22//ρρ + V+ V22

22/2g + [(U/2g + [(U22 –– UU11) ) –– W W –– Q]Q]

q + q + wwshaftshaft = (h= (h2 2 –– hh11) + (v) + (v2222 –– vv11

22)/2 + g(z)/2 + g(z22 ––zz11))

Z/z: fluid height;Z/z: fluid height; P: fluid pressure; P: fluid pressure; ρρ: fluid density : fluid density V/v: fluid velocityV/v: fluid velocity U: internal energyU: internal energy W/w: workW/w: workQ/q: heat transferredQ/q: heat transferred h: enthalpyh: enthalpy g: g: gravgrav. acceleration. acceleration

•• BOTTOM LINE: Total energy within the control volume is BOTTOM LINE: Total energy within the control volume is constant under SS conditions.constant under SS conditions.

Components of PumpsComponents of Pumps

•• Drive mechanism (steam, electric, gear)Drive mechanism (steam, electric, gear)

•• Pump shaftPump shaft

•• Impeller or pistonImpeller or piston

•• CasingCasing

Types of PumpsTypes of Pumps

•• Positive DisplacementPositive Displacement•• Fixed volume of fluid is displaced during Fixed volume of fluid is displaced during

each cycle regardless of static head/pressure each cycle regardless of static head/pressure pumping againstpumping against

•• Uses either a piston, gear, or screw type Uses either a piston, gear, or screw type (reciprocating, rotary gear, rotary screw, (reciprocating, rotary gear, rotary screw, etc)etc)

Positive Displacement PumpPositive Displacement Pump

PumpsPumps

•• NonNon--positive Displacementpositive Displacement: volume of : volume of fluid is dependent on static fluid is dependent on static head/pressurehead/pressure

•• CentrifugalCentrifugal: impeller inside a case (called : impeller inside a case (called volute). Impeller is a disc w/ curved vanes volute). Impeller is a disc w/ curved vanes mounted radially (like a paddle wheel)mounted radially (like a paddle wheel)

•• Suction is the Eye Suction is the Eye --> fluid accelerated as it travels > fluid accelerated as it travels outward & then enters voluteoutward & then enters volute

•• PropellerPropeller: uses prop inside casing to move : uses prop inside casing to move fluid fluid --> not used much in Navy> not used much in Navy

Centrifugal PumpCentrifugal Pump

PumpsPumps

•• Jet pumpsJet pumps: : •• BernoulliBernoulli’’s principle and no moving partss principle and no moving parts

•• Velocity Head vs. Pressure headVelocity Head vs. Pressure head

hin + vin2/2 = hout + vout

2/2

Jet PumpJet Pump

•• Types:Types:•• Eductor Eductor -- used to pump liquidsused to pump liquids

•• Ejector Ejector -- used to pump gasesused to pump gases

Pump Characteristic CurvesPump Characteristic Curves

•• Pump Parameters:Pump Parameters:•• N = pump speed, RPMN = pump speed, RPM•• V = volumetric flow rate, GPMV = volumetric flow rate, GPM•• HHpp = pump head (discharge pressure), psig= pump head (discharge pressure), psig•• P = power required, HpP = power required, Hp

•• Centrifugal Pump LawsCentrifugal Pump Laws•• V V αα NN•• HHpp αα NN22

•• W W αα NN33

Positive Displacement Pumps Positive Displacement Pumps

Hp

GPM

N1 N2

N2 = ____

Centrifugal PumpsCentrifugal Pumps

•• Parallel PumpsParallel Pumps

Hp

GPM

2 Pumps

1 Pump

V2 = ____

Hp2 = ____

Centrifugal PumpsCentrifugal Pumps

•• Series pumps (called staging)Series pumps (called staging)

Hp

GPM

V2 = ____

Hp2 = ____2 Pumps

1 Pump

FansFans

•• Same Principle as NonSame Principle as Non--positive positive displacement pumpsdisplacement pumps

•• Types:Types:•• Centrifugal: majority used for compressorsCentrifugal: majority used for compressors

•• Axial (like propeller): cooling fansAxial (like propeller): cooling fans

FansFans