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Engineer Study Guide > Ervens > Flashcards

Ervens Flashcards

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
Q

Volts

A

Amps x ohms

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25
Q

Electron flow

A

Negative to positive

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26
Q

Common ground

A

One wire completes circuit

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27
Q

Excessive burned out lights

A

Voltage meter set too high

28
Q

Amps/hour

A

Gas- 120 A/hr

Diesel- 200

29
Q

Lead acid battery

A

Alternating positive and negative plates
Acid bath
Sulfuric acid electrolyte
Discharged- lead sulphate

30
Q

12 V batt

A

6 cells 2.2 V per cell

31
Q

Hydrometer

A

Measures specific gravity

32
Q

Water fill in batteries

A

3/8-1/2” above plates

33
Q

Heat leaving the motor

A

1/3- horsepower
1/3- exhaust gases
1/3- dissipated by oil and airflow

34
Q

Common temps

A

Exhaust valves- 1200° F
Piston crown- 500°
Cylinder wall- 250°
Combustion chamber 3000-3500°

35
Q

Sludge effect

A

Resist coolant flow

Increased heat

36
Q

Coolant Characteristics

A
  • transfer hear from cylinders to atmosphere
  • prevent corrosion
  • prev scale and sludge
  • control pH
  • compatible w/ metal, hoses, etc
  • freeze protection
37
Q

Coolant ingredients

A

50% ethylene glycol/ 50% water

38
Q

Cooling system

A 
Pressure increases boiling  point
1 psi = 2.5 °F
15 psi cap
Boiling point 250°F
Antifreeze boiling pt. 265
39
Q

PCV Valve

A

prevents crankcase explosion.

closes upon backfire

40
Q

Crankcase Vent System

A

Vacuum of engine pulls fumes and clean air through the crankcase.
Burns as hydrocarbons.

41
Q

Fuel in oil?

Coolant in oil?

A

diaphragm tear in mech. fuel pump.

leak in head gasket/cracked block or head

42
Q

OIL FUNCTIONS

A
  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
Q

OIL BREAKDOWN

A

DOESN’T WEAR OUT. ADDITIVES AND DETERGENTS USED UP.

44
Q

AIR BRAKES

A

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
Q

FUEL FILTERS

A

STRAINER BETWEEN TANK/FUIEL PUMP

MOST IMPORTANT FILTER BET FUEL PUMP AND INJECTION PUMP/INLET MANIFOLD

46
Q

FUEL INJECTION PUMP/INLET MANIFOLD

A

FUEL PUMP-4 CYCLE

MANI- 2 CYCLE

47
Q

TYPES OF FRICTION

A

SLIDING, ROLLING, FLUID

48
Q

IGNITION PATH

A

BATTERY, WIRING, IGNITION, CHARGING SYSTEM

49
Q

SAFE DRIVING

A

20% SAFE VEH
20% GOOD PHY COND
60% GOOD ATTITUDE

50
Q

TURN SIGNAL BEFORE TURN

A

100 FT

51
Q

SIREN HEARD LESS AROUND A CORNER

A

2/3

52
Q

TOTAL STOPPING DIST

A

PERCEPTION-REACTION-VEHICLE BRAKING

53
Q

PERCEPT/REACTION TIME

A

1 1/2 SECONDS

54
Q

FLARE PLACEMENT

A

3-4 FLARES 100-0 FT

55
Q

FLARES ON A TURN

A

SEVERAL HUNDRED FEET

56
Q

COOLING SYST NORMAL WITH OVERHEAT

A

TRANS

57
Q

NORMAL OIL TEMP

A

160-200

NEVER EXCEED 250 ON ROAD 300 OFF ROAD

58
Q

TIME TO FULL THROTTLE

A

30 SECONDS

59
Q

SHIFT RESTRICTIONS

A

DOWNSHIFT IN VALVE BODY

NONE IN UPSHIFT

60
Q

Master stream

A

400 GPM

61
Q

Discharge piping capacity

A

250 GPM

62
Q

Increase rpm with no increase in pressure

A

Cavitation

63
Q

Priming pump air vent

A

Breaks siphon from tank so water doesn’t flow in

64
Q

Practical limit of draft

A

2/3 theoretical or 22.6 ft

65
Q

Loss in a battery at 0°F

A

10%

66
Q

Engine power loss per 1000 ft

A

3.5%

67
Q

Diesel engine power loss

A

none until 4000 ft then 2% per 1000 ft

68
Q

Water temp bad for drafting

A

Over 85°F

Engineer Study Guide (19 decks)

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