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Engineer Study Guide > Ervens > Flashcards

Ervens Flashcards

(69 cards)

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0
Q

Rotary Pumps

A
  • Take advantage of incoming pres.
  • twice as hard on draft
  • not good for high pressure
  • speed increases/water output increases
  • pressure = speed squared
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1
Q

Positive Displacement Pump

A

Little to no slip
Will pump air or water
Volume output same
Priming pump

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2
Q

Diff between actual and theoretical

A

Slip

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3
Q

Impeller/shaft materials

A

Impellers=brass (usually 2)

Shaft= steel (usually 1)

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4
Q

Rotary chambers

A

Separate suction/discharge

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5
Q

Centrifugal pump

A
  • Away from center
  • pressure = speed squared
  • constant quantity, speed, pressure
  • 100% slip
  • bronze impellers
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6
Q

Multistage pumps

A 
Volume= parallel (for low pressure/drafting)
Pressure= series (up to 70% of the pump rating)
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7
Q

Water flow through centrifugal

A

Eye of impeller to volute.

Back flow prevent by close fit of impeller hub to wear ring

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8
Q

Cavitation

A

Pressure inside pump drops below vapor pressure of the corresponding liquid. Liquid vaporizes and forms vapor bubbles. Vapor bubbles travel until higher pressure is reached. Bubbles collapse with a shock wave on adjacent walls.

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9
Q

Cavitation 2

A

Caused by reducing absolute pressure of water below boiling point.
Pumps suction of water and flashes to steam.

Water pushes in to fill void behind vapor bubbles collapse

Increase in RPM without increase in pressure.

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10
Q

Drop in horsepower

A

Increased: altitude and temp
Decrease O2

Pump reduced: hot water, low baro pres, high RH, elevated temp.

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11
Q

Draft 1500 GPM pump

A

30 seconds, 20 ft hard suction

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12
Q

Power decrease per 1000 ft

A

3%

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13
Q

Inspect and adjust before failure

A

Preventative maintenance

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14
Q

NFPA 1901

A

Fire Apparatus

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15
Q

Fuel tank capacity

A

Allow 2 hours running at pump capacity

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16
Q

Pump packing leak allowance

A

30-60 drops per minute

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17
Q

Sludge

A

Water vapor mixes with carbon and dirt.

Contaminate oil

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18
Q

Weekly checks

A

Priming, transfer, relief system, oil in priming pump

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19
Q

Oil in aerial systems

A

Transmission of power
Lube
Cool pumps and motor

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20
Q

Minimum viscosity index

A

Maintains viscosity under elevated temp

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21
Q

EMF

A

Electromotive force (volts)

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22
Q

Amps

A

Quantity of electrons passing

Volts/ohms

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23
Q

Ohms

A

Resistance to flow

Volts/amps

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24
Volts
Amps x ohms
25
Electron flow
Negative to positive
26
Common ground
One wire completes circuit
27
Excessive burned out lights
Voltage meter set too high
28
Amps/hour
Gas- 120 A/hr | Diesel- 200
29
Lead acid battery
Alternating positive and negative plates Acid bath Sulfuric acid electrolyte Discharged- lead sulphate
30
12 V batt
6 cells 2.2 V per cell
31
Hydrometer
Measures specific gravity
32
Water fill in batteries
3/8-1/2" above plates
33
Heat leaving the motor
1/3- horsepower 1/3- exhaust gases 1/3- dissipated by oil and airflow
34
Common temps
Exhaust valves- 1200° F Piston crown- 500° Cylinder wall- 250° Combustion chamber 3000-3500°
35
Sludge effect
Resist coolant flow | Increased heat
36
Coolant Characteristics
- transfer hear from cylinders to atmosphere - prevent corrosion - prev scale and sludge - control pH - compatible w/ metal, hoses, etc - freeze protection
37
Coolant ingredients
50% ethylene glycol/ 50% water
38
Cooling system
``` Pressure increases boiling point 1 psi = 2.5 °F 15 psi cap Boiling point 250°F Antifreeze boiling pt. 265 ```
39
PCV Valve
prevents crankcase explosion. | closes upon backfire
40
Crankcase Vent System
Vacuum of engine pulls fumes and clean air through the crankcase. Burns as hydrocarbons.
41
Fuel in oil? | Coolant in oil?
diaphragm tear in mech. fuel pump. | leak in head gasket/cracked block or head
42
OIL FUNCTIONS
1. PREVENT METAL-TO-METAL 2. CARRY HEAT AWAY 3. CLEAN ENGINE PARTS/HOLD CONTAMINATES IN SUSPENSION 4. FORM SEAL BETWEEN PISTON RINGS/CYL WALLS PREVENT BLOW BY OF GASES
43
OIL BREAKDOWN
DOESN'T WEAR OUT. ADDITIVES AND DETERGENTS USED UP.
44
AIR BRAKES
60 PSI BEFORE MOVING COMPRESSOR OIL BUILD 50-90 PSI IN LESS THAN 5 MIN (FAST IDLE) RELEASED NO MORE THAN 3 PSI OR 4 PSI APPLIED BLEED TANKS WEEKLY
45
FUEL FILTERS
STRAINER BETWEEN TANK/FUIEL PUMP | MOST IMPORTANT FILTER BET FUEL PUMP AND INJECTION PUMP/INLET MANIFOLD
46
FUEL INJECTION PUMP/INLET MANIFOLD
FUEL PUMP-4 CYCLE | MANI- 2 CYCLE
47
TYPES OF FRICTION
SLIDING, ROLLING, FLUID
48
IGNITION PATH
BATTERY, WIRING, IGNITION, CHARGING SYSTEM
49
SAFE DRIVING
20% SAFE VEH 20% GOOD PHY COND 60% GOOD ATTITUDE
50
TURN SIGNAL BEFORE TURN
100 FT
51
SIREN HEARD LESS AROUND A CORNER
2/3
52
TOTAL STOPPING DIST
PERCEPTION-REACTION-VEHICLE BRAKING
53
PERCEPT/REACTION TIME
1 1/2 SECONDS
54
FLARE PLACEMENT
3-4 FLARES 100-0 FT
55
FLARES ON A TURN
SEVERAL HUNDRED FEET
56
COOLING SYST NORMAL WITH OVERHEAT
TRANS
57
NORMAL OIL TEMP
160-200 | NEVER EXCEED 250 ON ROAD 300 OFF ROAD
58
TIME TO FULL THROTTLE
30 SECONDS
59
SHIFT RESTRICTIONS
DOWNSHIFT IN VALVE BODY | NONE IN UPSHIFT
60
Master stream
400 GPM
61
Discharge piping capacity
250 GPM
62
Increase rpm with no increase in pressure
Cavitation
63
Priming pump air vent
Breaks siphon from tank so water doesn't flow in
64
Practical limit of draft
2/3 theoretical or 22.6 ft
65
Loss in a battery at 0°F
10%
66
Engine power loss per 1000 ft
3.5%
67
Diesel engine power loss
none until 4000 ft then 2% per 1000 ft
68
Water temp bad for drafting
Over 85°F

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