about pumps, valves, & fans by deva
DESCRIPTION
Glands on Pumps, ValvesTRANSCRIPT
ENGINEERING LESSON GUIDE 4
PUMPS, VALVES, AND FANS
VALVES
TYPES OF VALVES
Globe valves - common type of stop valve– the disk seats on the seating ring– commonly used in, steam, air, water, and
oil lines– also used as throttle valves
TYPES OF VALVES
Gate valve - used for straight line flow and when minimum flow restriction are needed– not used for throttling– rising stem or nonrising stem– steam systems have flexible gates
TYPES OF VALVES
Butterfly valve - light weight, relatively small and quick-acting– has a body, resilient seat, butterfly disk, a
stem, packing, a notched position plate, and a handle
– very versatile - can be used for fresh water, salt water, JP-5, lube-oil, and chill water systems
Relief Valve
VALVE OPERATING DEVICES
Manual
Hydraulic
Motor (electric or air operated)
Solenoid
PUMPS
PUMP COMPONENTS
Drive– Steam, electric, or gear
Pump Shaft Impeller or Piston Casing
PUMP TYPES CENTRIFUGAL
– Single Stage– Multi-staged centrifugal pumps
POSITIVE DISPLACEMENT– Reciprocating– Rotary Gear– Screw– Moving vane
JET PUMP– Eductor– Ejector
POSITIVE DISPLACEMENT PUMP
Fixed Volume Volumetric Flow rate is
proportional to speed of the pump A relief valve will always be on the
discharge end of the pump
EXAMPLES
PRESSURE HEAD(Hp = ft lbf/ lbm)
CAPACITY(V=GPM)
N1 N2
ActualIdeal
Reciprocating PumpCharacteristic Curve
NON-POSITIVE DISPLACEMENT PUMPS
BERNOULLI’S THEOREM
Z1 + P1/D + 1/2(V12/g) =Z2 +P2/D +
1/2(V22/g) + gc/g(wk) + HL
Where: Z : Elevation (ft) P : Pressure (lbs/ft2) D : Density (lb/ft3) V : Velocity (ft/sec) g : acceleration (32.2 ft/sec2)
wk: work (ft-lbs) HL: Head Loss = f(L/D)(V2/2Zg) where f : friction factor L: Length D: Diameter
BERNOULLI’S PRINCIPLE
Basically: as the velocity (speed) of a fluid increases, its pressure decreases, and visa versa
PUMPS
Net Positive Suction Head: that pressure required at the suction of a pump to prevent cavitation.– cavitation: the formation of bubbles due to
area where P < PSAT, and the subsequent collapse of those bubbles.
• causes noise and damage due to erosion and fatigue failure.
PressureHead
V = GPM.
HP =(ft lbf)/ lbm
V NHp N2
Pw N3
. Where V = volumetric flow rate N = Speed of rotation Hp= Pump Head (discharge pressure Pw= Power required (prime mover)
N2 = 2N1
Characteristic curve for centrifugal pump
N1
N2
PUMPS
– Centrifugal:• Parallel pumps:
1 pump
2 pumpsHP
VGPM
V2 = 2V1
HP2 = HP1
PUMPS
• Series (called staging):
HP
VGPM
1 pump
2 pumps
Fans
Same Principle as Non-positive displacement pumps
Types:– Centrifugal: majority used for compressors– Axial (like propeller): cooling fans
QUESTIONS