PUMPS, VALVES, & FANS …Moving fluids

Objectives Comprehend the basic construction and application of valves used Comprehend the basic construction and application of valves used Comprehend the basic operation and application of different pumps Comprehend the basic operation and application of different pumps Know Bernoulli’s principle, the concept of pressure, & Net Positive Suction Head Know Bernoulli’s principle, the concept of pressure, & Net Positive Suction Head Be familiar with operation and application of centrifugal & axial fans Be familiar with operation and application of centrifugal & axial fans

Valves Def’n: devices which control the amount and direction of fluid flow in piping systems Def’n: devices which control the amount and direction of fluid flow in piping systems Typically made of bronze, brass, iron, or steel alloy Typically made of bronze, brass, iron, or steel alloy Components: Components: - Valve body- Packing - Disc- Packing gland/nut - Valve body- Packing - Disc- Packing gland/nut - Seat- Stem - Bonnet- Wheel

Types of Valves Two basic groups: Two basic groups: Stop valves - used to shut off or partially shut off the flow of fluid ( ex: globe, gate, plug, needle, butterfly) Stop valves - used to shut off or partially shut off the flow of fluid ( ex: globe, gate, plug, needle, butterfly) Check Valves - used to permit flow in only one direction (ex: ball-check, swing-check, lift- check) Check Valves - used to permit flow in only one direction (ex: ball-check, swing-check, lift- check) Special types: Special types: Relief valves Relief valves Pressure-reducing valves Pressure-reducing valves Remote-operated valves Remote-operated valves

Stop Valves Globe Valves Globe Valves Most common type of stop valve Most common type of stop valve Used in steam, air, water, & oil lines Used in steam, air, water, & oil lines Disc attached to valve stem rests against seat to shut off flow of fluid Disc attached to valve stem rests against seat to shut off flow of fluid Adv: Used for throttling Adv: Used for throttling Disadv: flow resistance Disadv: flow resistance

Globe Valve

Stop Valves Gate Valves Gate Valves Used when there must be straight-line flow of fluid w/ min. resistance Used when there must be straight-line flow of fluid w/ min. resistance Gate usually wedge-shaped or a vertical disc Gate usually wedge-shaped or a vertical disc Adv: No flow restrictions Adv: No flow restrictions Disadv: poor throttling Disadv: poor throttling

Gate Valve

Stop Valves Butterfly Valves Butterfly Valves Used in water, fuel, and ventilation systems Used in water, fuel, and ventilation systems Adv: small, light-weight, & quick-acting Adv: small, light-weight, & quick-acting Disadv: leaks early & only low-flow throttle Disadv: leaks early & only low-flow throttle Ball Valves Ball Valves Similar to butterfly valves Similar to butterfly valves Normally found in seawater, sanitary, trim and drain, and hydraulic systems Normally found in seawater, sanitary, trim and drain, and hydraulic systems

Butterfly Valve

Check Valves Controls direction of flow Controls direction of flow Operated by flow of fluid in pipe Operated by flow of fluid in pipe Types: Types: Swing check - disc moves through an arc Swing check - disc moves through an arc Lift check - disc moves up and down Lift check - disc moves up and down Ball check - ball is located at end of stem and lifts to allow flow Ball check - ball is located at end of stem and lifts to allow flow

Swing-check Valve

Relief Valves Used to protect piping system from excessive pressure Used to protect piping system from excessive pressure Opens automatically when fluid pressure becomes too high (pressure acts against spring pressure) Opens automatically when fluid pressure becomes too high (pressure acts against spring pressure) Relieving pressure set by an adjusting screw Relieving pressure set by an adjusting screw

Pressure-reducing Valves Used to automatically provide a steady, lower pressure to a system from a higher pressure source Used to automatically provide a steady, lower pressure to a system from a higher pressure source Used in air, lube-oil, seawater, and other systems Used in air, lube-oil, seawater, and other systems

Remote-operated Valves Valves that allow operation from distant stations Valves that allow operation from distant stations Types: Types: Mechanical - uses reach rods and gears Mechanical - uses reach rods and gears Hydraulic - uses fluid and piston set up Hydraulic - uses fluid and piston set up Motor - uses and electric or pneumatic motor Motor - uses and electric or pneumatic motor Solenoid - uses coil and core mechanism to open or close on an electric signal Solenoid - uses coil and core mechanism to open or close on an electric signal

Pumps

Pumps Def’n: device that uses and external power source to apply force to a fluid in order to move it from one place to another Def’n: device that uses and external power source to apply force to a fluid in order to move it from one place to another Must overcome: Must overcome: (1) frictional forces from large quantities of fluid (1) frictional forces from large quantities of fluid (2) difference in static pressure between two locations (2) difference in static pressure between two locations Must provide any velocity desired Must provide any velocity desired

Pumps – Bernoulli’s Theorem Pressure head: measure of fluid’s mech. PE Pressure head: measure of fluid’s mech. PE Velocity head: measure of fluid’s mech. KE Velocity head: measure of fluid’s mech. KE Friction head: measure of energy lost that heats fluid Friction head: measure of energy lost that heats fluid Z 1 + P 1 /  + V 1 2 /2g = Z 2 + P 2 /  + V 2 2 /2g + [(U 2 – U 1 ) – W – Q] q + w shaft = (h 2 – h 1 ) + (v 2 2 – v 1 2 )/2 + g(z 2 –z 1 ) Z/z: fluid height;P: fluid pressure;  : fluid density V/v: fluid velocityU: internal energyW/w: work Q/q: heat transferredh: enthalpyg: grav. acceleration BOTTOM LINE: Total energy within the control volume is constant under SS conditions. BOTTOM LINE: Total energy within the control volume is constant under SS conditions.

Components of Pumps Drive mechanism (steam, electric, gear) Drive mechanism (steam, electric, gear) Pump shaft Pump shaft Impeller or piston Impeller or piston Casing Casing

Types of Pumps Positive Displacement Positive Displacement Fixed volume of fluid is displaced during each cycle regardless of static head/pressure pumping against Fixed volume of fluid is displaced during each cycle regardless of static head/pressure pumping against Uses either a piston, gear, or screw type (reciprocating, rotary gear, rotary screw, etc) Uses either a piston, gear, or screw type (reciprocating, rotary gear, rotary screw, etc)

Positive Displacement Pump

Pumps Non-positive Displacement: volume of fluid is dependent on static head/pressure Non-positive Displacement: volume of fluid is dependent on static head/pressure Centrifugal: impeller inside a case (called volute). Impeller is a disc w/ curved vanes mounted radially (like a paddle wheel) Centrifugal: impeller inside a case (called volute). Impeller is a disc w/ curved vanes mounted radially (like a paddle wheel) Suction is the Eye -> fluid accelerated as it travels outward & then enters volute Suction is the Eye -> fluid accelerated as it travels outward & then enters volute Propeller: uses prop inside casing to move fluid -> not used much in Navy Propeller: uses prop inside casing to move fluid -> not used much in Navy

Centrifugal Pump

Pumps Jet pumps: Jet pumps: Bernoulli’s principle and no moving parts Bernoulli’s principle and no moving parts Velocity Head vs. Pressure head Velocity Head vs. Pressure head h in + v in 2 /2 = h out + v out 2 /2

Jet Pump Types: Types: Eductor - used to pump liquids Eductor - used to pump liquids Ejector - used to pump gases Ejector - used to pump gases

Pump Characteristic Curves Pump Parameters: Pump Parameters: N = pump speed, RPM N = pump speed, RPM V = volumetric flow rate, GPM V = volumetric flow rate, GPM H p = pump head (discharge pressure), psig H p = pump head (discharge pressure), psig P = power required, Hp P = power required, Hp Centrifugal Pump Laws Centrifugal Pump Laws V  N V  N H p  N 2 H p  N 2 W  N 3 W  N 3

Positive Displacement Pumps HpHp GPM N1N1 N2N2 N 2 = ____

Centrifugal Pumps Parallel Pumps Parallel Pumps HpHp GPM 2 Pumps 1 Pump V 2 = ____ H p2 = ____

Centrifugal Pumps Series pumps (called staging) Series pumps (called staging) HpHp GPM V 2 = ____ H p2 = ____ 2 Pumps 1 Pump

Fans Same Principle as Non-positive displacement pumps Same Principle as Non-positive displacement pumps Types: Types: Centrifugal: majority used for compressors Centrifugal: majority used for compressors Axial (like propeller): cooling fans Axial (like propeller): cooling fans

Fans

Questions? Questions?