pumps, valves, & fans
DESCRIPTION
PUMPS, VALVES, & FANS. …Moving fluids. Objectives. Comprehend the basic construction and application of valves used Comprehend the basic operation and application of different pumps Know Bernoulli’s principle, the concept of pressure, & Net Positive Suction Head - PowerPoint PPT PresentationTRANSCRIPT
PUMPS, VALVES, PUMPS, VALVES, & FANS& FANS
……Moving fluidsMoving fluids
ObjectivesObjectives• Comprehend the basic construction Comprehend the basic construction
and application of valves usedand application of valves used• Comprehend the basic operation and Comprehend the basic operation and
application of different pumpsapplication of different pumps• Know Bernoulli’s principle, the Know Bernoulli’s principle, the
concept of pressure, & Net Positive concept of pressure, & Net Positive Suction HeadSuction Head
• Be familiar with operation and Be familiar with operation and application of centrifugal & axial fansapplication of centrifugal & axial fans
ValvesValves• Def’n: devices which control the Def’n: devices which control the
amount and direction of fluid flow in amount and direction of fluid flow in piping systemspiping systems• Typically made of bronze, brass, iron, Typically made of bronze, brass, iron,
or steel alloyor steel alloy• Components:Components: - Valve body- Valve body - Packing- Packing - -
DiscDisc - Packing gland/nut- Packing gland/nut- Seat- Seat - Stem- Stem - Bonnet- Bonnet - Wheel - Wheel
Types of ValvesTypes of Valves• Two basic groups:Two basic groups:
• Stop valves - used to shut off or Stop valves - used to shut off or partially shut off the flow of fluid ( ex: partially shut off the flow of fluid ( ex: globe, gate, plug, needle, butterfly)globe, gate, plug, needle, butterfly)
• Check Valves - used to permit flow in Check Valves - used to permit flow in only one direction (ex: ball-check, only one direction (ex: ball-check, swing-check, lift-check)swing-check, lift-check)
• Special types:Special types:• Relief valvesRelief valves• Pressure-reducing valvesPressure-reducing valves• Remote-operated valvesRemote-operated valves
Stop ValvesStop Valves• Globe ValvesGlobe Valves
• Most common type of stop valveMost common type of stop valve• Used in steam, air, water, & oil Used in steam, air, water, & oil
lineslines• Disc attached to valve stem rests Disc attached to valve stem rests
against seat to shut off flow of against seat to shut off flow of fluidfluid
• 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 Used when there must be straight-line flow of fluid w/ min. straight-line flow of fluid w/ min. resistanceresistance
• Gate usually wedge-shaped or a Gate usually wedge-shaped or a vertical discvertical 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 Used in water, fuel, and ventilation systemssystems
• AdvAdv: small, light-weight, & quick-acting: small, light-weight, & quick-acting• DisadvDisadv: leaks early & only low-flow : leaks early & only low-flow
throttlethrottle• Ball ValvesBall Valves
• Similar to butterfly valvesSimilar to butterfly valves• Normally found in seawater, sanitary, Normally found in seawater, sanitary,
trim and drain, and hydraulic systemstrim and 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 - disc moves through Swing check - disc moves through an arcan arc
• Lift check - disc moves up and downLift check - disc moves up and down• Ball check - ball is located at end of Ball check - ball is located at end of
stem and lifts to allow flowstem and lifts to allow flow
Swing-check ValveSwing-check Valve
Relief ValvesRelief Valves• Used to protect piping system Used to protect piping system
from excessive pressurefrom excessive pressure• Opens automatically when Opens automatically when
fluid pressure becomes too fluid pressure becomes too high (pressure acts against high (pressure acts against spring pressure)spring pressure)
• Relieving pressure set by an Relieving pressure set by an adjusting screwadjusting screw
Pressure-reducing Pressure-reducing ValvesValves
• Used to automatically provide Used to automatically provide a steady, lower pressure to a a steady, lower pressure to a system from a higher pressure system from a higher pressure sourcesource
• Used in air, lube-oil, seawater, Used in air, lube-oil, seawater, and other systemsand other systems
Remote-operated Remote-operated ValvesValves
• Valves that allow operation from Valves that allow operation from distant stationsdistant stations
• Types:Types:• Mechanical - uses reach rods and gearsMechanical - uses reach rods and gears• Hydraulic - uses fluid and piston set upHydraulic - uses fluid and piston set up• Motor - uses and electric or pneumatic Motor - uses and electric or pneumatic
motormotor• Solenoid - uses coil and core Solenoid - uses coil and core
mechanism to open or close on an mechanism to open or close on an electric signalelectric signal
PumpsPumps
PumpsPumps• Def’n: device that uses and Def’n: device that uses and
external power source to apply external power source to apply force to a fluid in order to move force to a fluid in order to move it from one place to anotherit from one place to another
• Must overcome:Must overcome:• (1) frictional forces from large (1) frictional forces from large
quantities of fluidquantities of fluid• (2) difference in static pressure (2) difference in static pressure
between two locationsbetween two locations• Must provide any velocity Must provide any velocity
desired desired
Pumps – Bernoulli’s Pumps – Bernoulli’s TheoremTheorem
• Pressure head: measure of fluid’s mech. PEPressure head: measure of fluid’s mech. PE• Velocity head: measure of fluid’s mech. KEVelocity head: measure of fluid’s mech. KE• Friction head: measure of energy lost that Friction head: measure of energy lost that
heats fluid heats fluid
ZZ11 + P + P11// + V + V1122/2g = Z/2g = Z22 + P + P22// + V + V22
22/2g + [(U/2g + [(U22 – U – U11) – W – Q]) – W – Q]
q + wq + wshaftshaft = (h = (h2 2 – h– h11) + (v) + (v2222 – v – v11
22)/2 + g(z)/2 + g(z22 –z –z11))
Z/z: fluid height;Z/z: fluid height; P: fluid pressure; P: fluid pressure; : 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: grav. accelerationg: grav. acceleration
• BOTTOM LINE: Total energy within the control BOTTOM LINE: Total energy within the control volume is constant under SS conditions.volume is constant under SS conditions.
Components of PumpsComponents of Pumps• Drive mechanism (steam, Drive mechanism (steam,
electric, gear)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 Fixed volume of fluid is displaced during each cycle regardless of during each cycle regardless of static head/pressure pumping static head/pressure pumping againstagainst
• Uses either a piston, gear, or Uses either a piston, gear, or screw type (reciprocating, rotary screw type (reciprocating, rotary gear, rotary screw, etc)gear, rotary screw, etc)
Positive Displacement Positive Displacement PumpPump
PumpsPumps• Non-positive DisplacementNon-positive Displacement: :
volume of fluid is dependent on volume of fluid is dependent on static head/pressurestatic head/pressure• CentrifugalCentrifugal: impeller inside a case : impeller inside a case
(called volute). Impeller is a disc w/ (called volute). Impeller is a disc w/ curved vanes mounted radially (like curved vanes mounted radially (like a paddle wheel)a paddle wheel)
• Suction is the Eye -> fluid accelerated as it Suction is the Eye -> fluid accelerated as it travels outward & then enters volutetravels outward & then enters volute
• PropellerPropeller: uses prop inside casing to : uses prop inside casing to move fluid -> not used much in Navymove fluid -> not used much in Navy
Centrifugal PumpCentrifugal Pump
PumpsPumps• Jet pumpsJet pumps: :
• Bernoulli’s principle and no Bernoulli’s principle and no moving partsmoving parts
• Velocity Head vs. Pressure headVelocity Head vs. Pressure head
hin + vin2/2 = hout + vout
2/2
Jet PumpJet Pump• Types:Types:
• Eductor - used to pump liquidsEductor - used to pump liquids• Ejector - used to pump gasesEjector - used to pump gases
Pump Characteristic Pump Characteristic CurvesCurves
• 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), = pump head (discharge pressure),
psigpsig• P = power required, HpP = power required, Hp
• Centrifugal Pump LawsCentrifugal Pump Laws• V V N N• HHpp N N22
• W W N N33
Positive Displacement Positive Displacement Pumps 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 Non-positive Same Principle as Non-positive
displacement pumpsdisplacement pumps• Types:Types:
• Centrifugal: majority used for Centrifugal: majority used for compressorscompressors
• Axial (like propeller): cooling fansAxial (like propeller): cooling fans
FansFans
Questions?Questions?QuestionQuestion
s?s?