PUMPS & VALVES

…Moving fluids

Types of Valves

Two basic groups:

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)

Special types:

Relief valves

Pressure-reducing valves

Remote-operated valves

Stop Valves

Globe Valves

Most common type of stop valve

Used in steam, air, water, & oil lines

Disc attached to valve stem rests against seat to

shut off flow of fluid

Adv: Used for throttling

Disadv: flow resistance

Globe Valve

Stop Valves

Gate Valves

Used when there must be straight-line flow of

fluid w/ min. resistance

Gate usually wedge-shaped or a vertical disc

Adv: No flow restrictions

Disadv: poor throttling

Gate Valve

Stop Valves

Butterfly Valves

Used in water, fuel, and ventilation systems

Adv: small, light-weight, & quick-acting

Disadv: leaks early & only low-flow throttle

Ball Valves

Similar to butterfly valves

Normally found in seawater, sanitary, trim and

drain, and hydraulic systems

Butterfly Valve

Check Valves

Controls direction of flow

Operated by flow of fluid in pipe

Types:

Swing check - disc moves through an arc

Lift check - disc moves up and down

Ball check - ball is located at end of stem and

lifts to allow flow

check Valve

Relief Valves

Used to protect piping system from

excessive pressure

Opens automatically when fluid pressure

becomes too high (pressure acts against

spring pressure)

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 in air, lube-oil, seawater, and other

systems

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

Must overcome:

(1) frictional forces from large quantities of fluid

(2) difference in static pressure between two locations

Must provide any velocity desired

Components of Pumps

Drive mechanism (steam, electric, gear)

Pump shaft

Impeller or piston

Casing

Types of Pumps

Positive Displacement

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)

Positive Displacement Pump

Pumps

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)

• 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

Centrifugal Pump

We’re Done!

You Made it to the End!