3. 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
4. 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
6. 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
8. 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
10. 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
12. 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
13. 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
15. 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
16. Components of Pumps
Drive mechanism (steam, electric, gear)
Pump shaft
Impeller or piston
Casing
17. 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)
19. 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
