TQ 4th period Flashcards
Bent Shaft produces the highest vibration at?
1X rpm
Misalignment can be distinguished from an imbalance vibration because?
Axial readings will be high compared to radial
Which condition will produce a frequency less than 1x frequency?
Oil whirl
High axial readings showing a 180 degree change of phase between bearings is an indication of?
Bent shaft
Velocity is used as a measurement of vibration frequency in the range of?
600 to 60,000 cpm
Phase readings are expressed in?
Degrees
For vibration measurements which device converts mechanical vibrations into electrical signal?
Velocity transducer
Rigid rotor is one that which operates?
Considerably below its first critical speed
The frequency of vibration caused by an imbalance would be?
1x the rpm
Displacement is measured as?
Mills peak to peak
Velocity is measured as?
Inches per second, peak
Acceleration is a rate of change of?
Velocity
The vibration characteristic referring to a type of resonance which occurs in a rotating machine component revolves at a speed close to its natural frequency is known as?
Critical speed
A gradual deviation from a desired governor speed would be known as?
Speed drift
Direct acting mechanical type governors utilize?
Centrifugal forces and mechanical linkage to operate SAV (Steam admission valve)
The governor characteristic that requires a specific speed decrease before the governor tries to give an increase in throttle is called?
Speed droop
The purpose of the mechanical flyball governor is to?
Maintain the selected speed
The governor that will keep a large diesel running at a constant speed regardless of varying load is called?
Isochronous
When a steam turbine is reaching top speed the flyweights on the governor will?
Be moving away from center increasing the force acting on the speeder spring
The dilution zone on a gas turbine combustion chamber is where?
secondary air is mixed with the burnt gases.
When a gas turbine exhausts to a heat recovery steam generator it’s called?
Cogeneration
Which type of gas combustors must be equipped with their own igniters?
Can type
What will cause the most pitting wear on the blades of a gas turbine?
Unburned liquid fuels
Turbine sections of a gas turbine has fewer stages than the steam turbine because?
The pressure drop is smaller.
The spherical seats used on radial bearings on large speed turbines allow for?
Fairing movement of the shaft if there’s any deflection
A large industrial steam turbine that is Cross compounded would have?
The shafts running parallel to each other
The purpose of the jacking oil pump on a large steam turbine is?
To lift the rotor off the bearings before starting to rotate the shaft
In a gas turbine the majority of the compressed air from the compressor is used?
To supply secondary cooling air
The highest air pressure in a gas turbine engine will be found in the?
Diffuser
The efficiency of a gas turbine depends primarily on?
The temperature that the air can be raised to.
Labyrinth seals in a steam turbine operate on the principle of?
Turbulent flow forming a pressure drop across each knife edge
One method commonly used to balance the thrust on the low pressure section of a reaction type steam turbine is to?
Have a double flow design casing
What is used to reduce the amount of steam leaking past the tips of the rotor blades?
A shroud with a labyrinth seal
The clearance specified by the manufacturer on carbon ring seals on a steam turbine will be most affected by?
Operating temperature
Carbon rings are efficient because?
There is only a small clearance between them and the shaft
A vortex in the suction reservoir can be caused by?
Incorrect suction pipe submergence in the suction reservoir.
Double suction pumps will require _________ seals for operation.
2
The purpose of having tilting pads on a kingsbury thrust bearing its to?
Allow each pad to form an oil wedge
In the reaction turbine there will be a pressure drop across?
Moving blades with a velocity increase across the fixed
The purpose of the barring gear found on a large steam turbine is?
To reduce the chance of bowing the rotor after shutdown
When referring to centrifugal pumps the term net positive suction head available is?
The pressure that remains after vapour pressure, suction pressure and all losses have been subtracted
Cavitation could be caused by?
Anything that impedes the flow on the suction side
High speed and regenerative pumps will produce
High heads and low flows
As a rule of thumb the maximum amount of wear ring clearance is?
3x the initial clearance
In a multi -stage deep well pumps _____ _______ impellers are often used
Mixed flow
If the discharge valve on a centrifugal pump is closed while the pump is still running what would happen?
Internal slippage would allow the impeller to still turn fluid.
A pump operating in high elevations would be susceptible to?
Cavitation
Which type of load is balanced with a double volute casing?
Radial
How many pump strokes are there in a complete cycle of a double acting duplex reciprocating pump?
4
A Pump suddenly does not deliver fluid at the rate of discharge pressure, becomes noisy but there is a good supply of fluid at the reservoir. What maybe the problem?
Suction line may be plugged.
The priming of a centrifugal pump before start up is often necessary because?
It is necessary to create the pressure at the eye of the impeller
The major advantage of a crown pulley is?
It will help to hold the belt on center.
A troughing conveyor belt will?
Increase carrying capacity
Which method would be best suited for making a temporary repair on a torn belt?
Double plate fasteners
A tripper is?
Used to unload a belt
A pneumatic conveyance system with rotary vane gears prevent?
The air from entering material inlet chute
What would be used to increase the arc of contact on a slipping drive pulley?
A snub pulley
When the material to be conveyed contains large lumps the impact on the belt can be reduced by the use of?
Grizzly chute
For curves in a roller conveyor bed the best type of roller to use?
Tapered roller
Rigid side guide idlers should be set up so they prevent?
The belt wearing on any fixed surface
The minimum number of rollers under a product on a rolling conveyor is?
3
The method of conveyance that uses a cushion of air to convey material is?
Gravity air slide
One sign of blocked crankcase vent line or breather would be?
Excessive oil consumption
Which engine fuel system would use a spray bar in the fuel delivery system?
LPG
While checking main bearing clearances in an integral engine compressor set must be?
- flywheel pinned and locked.
- fuel and starter system locked.
The natural gas engine has an elevated exhaust temperature this could be caused by?
Incorrect air fuel mixture
The result of a misaligned con-rod can be?
Excessive oil consumption
Bearing crush allows for?
Good heat transfer
Valve clearances on a 4 stroke engine are normally adjusted with the piston?
TDC on compression stroke
Excessive clearance between your position ring and piston groove can cause?
Broken rings
Too little valve clearance in the exhaust may cause?
Burnt valves
As the valve seat wears in on the exhaust valve?
Tappet clearances will be reduced
A roots blower on a 2 stroke engine is driven how?
Mechanically driven
Black smoke and loss of power being noticed on a large stationary Diesel engine the likely problem is?
Injection timing is out
Purpose of the lubrication system on a large engine would be?
- clean, lubricate, seal and cool
- absorb shock loading.
On a low tension electronic type magneto system uses the ____________ to discharge the system.
Capacitor
With electronic ignition systems distributor type switching of primary circuit is done with?
Transistors
Multiple engine systems coupling the exhaust systems together is?
Not recommended
Which fuel has your highest BTU rating?
Diesel
The higher the octane rating the?
Less chance of detonation
Excessive valve clearance in an engine could cause?
A change in timing
Installing a thinner head gasket on an engine could result in?
An increase in power and an increase in compression ratio
After honing what would be the best to clean a cylinder with?
Hot soapy water
Excessive crankshaft deflection would likely be caused by?
An engine improperly shimmed to the base plate
Counter weights bolted to the crankshaft in a large stationary engine are there to?
Counter act the reciprocating forces of the pistons and con-rod
On a 12 cylinder 4 stroke engine the engine must have how many revolutions for all cylinders to fire?
2
Rotation of a 3 phase motor can be changed by ?
Interchanging any of the 2 leads
Emergency stop switches are?
In series with control relays and are normally closed
Which program is a timed based maintenance program?
Preventative maintenance
Why would a root cause analysis be performed?
Find out why a machine failed.
When you make a change to piece of equipment, where does the information need to be entered?
CMMS
Computerized maintenance management system
In doing a rim and face alignment the face reading can indicate?
- angular misalignment
- axial float
A strain gauge can be used to measure?
Crankshaft deflection
When a piston on an engine travels from the Top Dead Centre position to the Bottom Dead Centre position and takes on fuel, the piston has traveled thru the ____________ stroke.
Intake
The type of turbine governor that senses speed through the volume of oil per revolution is that?
Hydraulic governor
The harmonic balancer is mounted on the _________ of the crankshaft.
Nose
The type of air filter that throws the dirt particles outward and into a collector is the ___________ cleaner.
Spiral Rotor air cleaner
As a General rule an engine requires ___________ cfm of air per rated horsepower.
2.5
An electric speed sensing governor used on an electric generator will monitor the?
Frequency of the current produced
Gas turbines use _________ seals on both the compressor and the turbine.
Labyrinth seals
If there is too little valve to stem clearance on an engine valve it could result in?
Valve sticking
With phase angle measurement using a vibration probe, the distance that the heavy spot move past the pick up before the flash occurs is the?
Flash angle
A common approach for selecting trial weight is to use a weight that will produce an imbalance force at the support bearing equal to ________% of the rotor weight supported by the bearing.
10%
When using a gas lubricated seal the _________ should be taken into consideration.
Corrosive properties of the liquid.
When troubleshooting the operation of a pump, the net clear area of the strainer on the suction line should be__________ times the area of the suction line.
4
When referring to pulsation dampers, which style normally has a low level limit switch as part of the damper?
Non-separated
What type of belt is usually used with electric motors with a separate speed reducer?
V-belt
A _________ Pitch used as feeder screws to provide for uniform withdrawal of fine material along the entire length of the screw.
Variable
The term specific gravity is the?
Ratio of the density of a substance compared to the density of water
Steam turbine has?
External combustion engine
Excessive connecting rod bearing clearances would cause?
Blue Smoke
Carbon mechanical seal is?
Low friction, economical
PTFE wedge is a?
Pusher seal
Which gas requires a computerized control system?
Methane
