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175 Cards in this Set
- Front
- Back
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How can the specific gravity of a liquid or solid be expressed? |
As a ratio between the weight of the substance and the weight of an equal volume of water
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The purpose of your textbook, Fluid Power, is to provide you with
• information on fluid power application for specific equipment • a basic reference concerning fundamentals of fluid power • a basic guide for use in maintaining hydraulic equipment • a reference concerning advanced concepts of fluid power |
a basic reference concerning fundamentals of fluid power
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A device used for measuring the specific gravity of a liquid is known as a
• hydrometer • hydroscope • hydrostat • hydrography |
hydrometer
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The critical factors affecting the state of matter are
• density and specific gravity • pressure and density • pressure and temperature • temperature and weight |
pressure and density
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The study of hydraulics was originally confined to the study of the physical behavior of water at rest and in motion. The term “hydraulics” now includes the physical behavior of all
• gases • liquids • liquids, gases, and solids • liquids and gases |
liquids
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The head, or pressure due to the weight of a fluid, depends on the density of the fluid and the
• area of the bottom surface of the container • vertical height of the fluid • geometric shape of the container • total volume of the fluid |
area of the bottom surface of the container
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Pressure can be measured in terms of force per unit area.
• True • False |
True
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Pascal’s law pertains to the
• differences of floating and submerged bodies • construction of aqueducts • transmission of force in confined fluids • use of water wheels for doing work |
transmission of force in confined fluids
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What change, if any, will occur in the volume and weight of a substance if its temperature changes?
• Its weight will change, but its volume will remain constant • Its volume will change, but its weight will remain constant • Both its volume and weight will be unaffected • Both its volume and weight will change |
Its volume will change, but its weight will remain constant
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Which statement about specific gravity is false?
• Specific gravity of a substance should be measured at a standardized temperature and pressure • The density of a solid can be determined by multiplying its specific gravity times the density of water • Specific gravity will vary with the size of the sample being tested • Specific gravity can also be described as specific weight or specific density |
Specific gravity will vary with the size of the sample being tested
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The pressure of force exerted on the end of a rigid metal bar is applied equally and undiminished to all surfaces of the bar.
• True • False |
True
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Which of the following is a favorable characteristic of a fluid power system?
• Very large forces can be controlled by much smaller ones • Different parts of the system can be located at widely separated points • Motion can be transmitted without the slack inherent in the use of solid machine parts • Each of the above |
Each of the above
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What is the specific gravity of a solid object which weighs 49.92 pounds per cubic foot?
• 2.7 • 0.9 • 0.8 • 0.789 |
2.7
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The side of a thin-walled chamber partially evacuated of air is the source of movement for the
• Fahrenheit thermometer • hydrometer • mercury thermometer • aneroid barometer |
aneroid barometer
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Lines A and B are pressurized to 50 psi. How much force is applied to each surface and which way will the piston move?
• C = 1000 pounds, D = 1250 pounds, piston will move to the left • C = 1250 pounds, D = 1000 pounds, piston will move to the left • C = 1250 pounds, D = 1000 pounds, piston will move to the right • C = 1000 pounds, D = 1250 pounds, piston will move to the right |
C = 1250 pounds, D = 1000 pounds, piston will move to the left
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Assume that the output piston has a diameter of 6 inches and is subject to a pressure of 10 pounds per square inch. What is the force exerted on the output piston?
• 31.4 pounds • 314.0 pounds • 282.6 pounds • 28.26 pounds |
31.4 pounds
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The term “fluid power” includes hydraulics and pneumatics, and is power that is applied through liquids or gases pumped or compressed to provide force and motion to mechanisms.
• True • False |
True
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All matter is classified according to its state as a solid, a liquid, or a gas.
• True • False |
True
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What is the specific gravity of a liquid which weighs 44 pounds per cubic foot at 4°C?
• 0.705 • 0.789 • 0.624 • 0.440 |
0.440
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Assume that the input piston has an area of 3 square inches with a force of 45 pounds. What is the pressure in the system?
• 5 psi • 15 psi • 10 psi • 20 psi |
15 psi
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What is the density of a solid that has a specific gravity of 2.5?
• 312 pounds per cubic foot • 156 pounds per cubic foot • 482 pounds per cubic foot • 250 pounds per cubic foot |
250 pounds per cubic foot
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The reference standard used as an indicator of atmospheric pressure is a column of mercury that at sea level is
• 29.92 inches high at 4°C • 76 inches high at 0°C • 76 centimeters high at 4°C • 76 centimeters high at 0°C |
76 centimeters high at 0°C
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The pressure in line A is 200 psi. No force is exerted on shaft S. How much pressure will be required in line B to prevent the piston from moving?
• 250 psi • 500 psi • 160 psi • 200 psi |
500 psi
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In the metric system the density of a substance is its weight in
• grams per cubic foot • grams per cubic centimeter • pounds per cubic centimetre • pounds per cubic foot |
grams per cubic centimeter
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Which of the following is a special problem of fluid power systems?
• Loss in efficiency as the force of the fluid is conveyed up and down or around corners • Loss of force as the fluid is transmitted over considerable distances • Leaks • Each of the above |
Leaks
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Which statement about a hydraulic liquid that is continuously subjected to high temperature conditions is true?
• It changes unfavorably in composition • The carbon and sludge formed in it are of little concern if the reservoir temperature remains normal • It accumulates moisture • Its life is unaffected by the hours of use |
The carbon and sludge formed in it are of little concern if the reservoir temperature remains normal
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For two pistons in the same fluid power system, the distances moved are inversely proportional to the
• volume of fluid moved • expansion of the fluid • areas of the pistons • pressure of the fluid |
areas of the pistons
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A liquid that is satisfactory for use in a hydraulic system provides
• good lubrication and a viscosity that decreases as temperature increases • good lubrication and sealing qualities, and a viscosity that does not result in an increase in flow resistance in” system piping • a low viscosity index, good sealing quality, and lubricity • a high viscosity index, good sealing quality, and a low flashpoint |
good lubrication and sealing qualities, and a viscosity that does not result in an increase in flow resistance in” system piping
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In fluid power system using liquids, the measurement of the volume of fluid flow is made in units of
• gallons per minute • cubic yards per minute • cubic inches per minute • cubic feet per minute |
gallons per minute
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Which factors affecting fluid action are classified as static factors?
• Gravity, atmospheric pressure, and applied forces • Gravity, applied forces, and friction • Atmospheric pressure, applied forces , and inertia • Applied forces, inertia, and friction |
Gravity, atmospheric pressure, and applied forces
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The viscosity reading of a liquid is expressed as Saybolt universal seconds (SUS), which represents the time, in seconds, it takes for 60 cubic centimeters of the liquid at a specified temperature to pass through an orifice of given diameter.
• True • False |
False
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Which component of a hydraulic fluid power system performs the same function as the receiver in a pneumatic fluid power system?
• Compressor • Selector valve • Actuator • Reservoir |
Reservoir
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Which of the following statements is NOT a true statement of fluid viscosity?
• There is a large choice of liquids available for the viscosity range required • An ideal fluid viscosity remains constant throughout temperature changes • The average hydraulic fluid has a relatively low viscosity • Liquids derived from the same source have equal resistance to heat |
The average hydraulic fluid has a relatively low viscosity
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Liquids rather than gases are used in hydraulic systems because liquids are
• less compressible • more expensive • less corrosive to system components • more compressible |
less corrosive to system components
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What is inertia of fluids in a power system?
• The force required to maintain the fluid at constant velocity • The force required to overcome friction • The resistance of the fluid to movement or change of rate of movement • The capacity to move and change rate of flow |
The capacity to move and change rate of flow
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Two pistons with different crosssectional areas will travel at the same speed as long as the rate of fluid flow into their cylinders is identical.
• True • False |
False
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There can be no static head if the fluid is in motion.
• True • False |
False
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Water flows through a pipe of 5 square-inch cross section at the velocity of 3 feet per second (fps). At what velocity does it flow through a constriction in the pipe with a cross section of 3 square inches?
• 3.0 fps • 5.0 fps • 3.6 fps • 1.8 fps |
5.0 fps
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Gravity head depends on which portions of the system are exposed to open air.
• True • False |
True
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The desirable flashpoint of a hydraulic liquid is one which provides a
• low degree of evaporation and good resistance to combustion • high degree of evaporation and poor resistance to combustion • high degree of evaporation and high resistance to combustion • low degree of evaporation and low resistance to combustion |
low degree of evaporation and low resistance to combustion
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The film strength and lubricating qualities of a liquid are directly related to the liquid’s physical properties.
• True • False |
True
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A low V.I. indicates that a liquid will
• maintain a constant viscosity over a wide temperature range • vary only slightly in viscosity with changes in temperature • vary greatly in viscosity with changes in temperature • have a response to temperature changes very much like the response of paraffinic oil |
vary greatly in viscosity with changes in temperature
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Velocity head is the loss of energy caused by inertia.
• True • False |
False
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In streamline flow, each particle of fluid moves in what manner?
• At the same velocity in the center of the pipe as along the walls • In uniform helical swirls • In parallel layers • At a velocity proportional to the cross-sectional area of the pipe |
In parallel layers
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Head is a statement of force per unit area.
• True • False |
False
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Friction head cannot exist without velocity head.
• True • False |
True
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Losses due to friction increase with velocity at a higher rate in turbulent flow than in streamline flow.
• True • False |
True
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Hydraulic liquid must possess which of the following properties?
• Chemical stability and freedom from acidity • Lubricating ability and proper viscosity • Minimum toxicity and high flashpoint • All of the above |
All of the above
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Neglecting friction, how much force is required to accelerate 3 pounds of fluid from rest to a velocity of 322 feet per second in 2 seconds?
• 3.0 pounds • 15 pounds • 1.5 pounds • 30 pounds |
3.0 pounds
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Slippage is the term given to the amount of fluid that can return from the discharge side to the suction side of a rotary pump through the space or clearances between the stationary and moving parts.
• True • False |
True
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Which of the following agents should parts of a hydraulic component be cleaned with prior to being assembled?
• An approved dry-cleaning solvent • Trichlorotrifluoroethane • Chlorinated solvents • Each cf the above |
An approved dry-cleaning solvent
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Although manufacturers strive to produce hydraulic liquids that contain no toxic chemicals, some liquids contain chemicals that are harmful. How do these poisonous chemicals enter the body?
• Absorption through the skin • Through the eyes or mouth • Through inhalation • All of the above |
All of the above
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By which of the following ways may air enter into a hydraulic system?
• Through improper maintenance • Past leaky seals in gas pressurized accumulators • Past actuator piston rod seals • Each of the above |
Past actuator piston rod seals
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What is the moat widely used medium for hydraulic systems?
• Vegetable-based liquid • Synthetic-based liquid • Petroleum-based liquid • Water-based liquid |
Petroleum-based liquid
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In contrast to a non-positive displacement pump that can operate with its discharge outlet completely restricted, a positive-displacement pump cannot do so and must be used with a pressure regulator.
• True • False |
True
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You are required to dispose of contaminated synthetic fluid while deployed. HOW should you dispose of the fluid?
• Dilute it with soapy water and pump it over the side • Pump it over the side • Place it in drums for disposal ashore • Pump it to the collecting, holding, and transfer (CHT) tank |
Pump it to the collecting, holding, and transfer (CHT) tank
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If a hydraulic pump is located below the reservoir, fluid is supplied to its inlet port by which of the following forces?
• Fluid head • Gravity • Atmospheric pressure • A combination of all of the Above |
Atmospheric pressure
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Pump performance can be expressed in which of the following terms?
• Gallons per minute • Cubic inches per revolution • Both 1 and 2 above • Cubic feet per minute |
Cubic inches per revolution
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Compatibility of hydraulic liquid with the seals and hoses in a system prevents which of the following problems from occurring?
• Chemical reaction between the liquid acid the seal or hose material and consequent breakdown of these parts • Gum formation around the seals and within the hoses • Condensation of moisture within the system • Deposits of contaminants on the seals and within the hoses |
Chemical reaction between the liquid acid the seal or hose material and consequent breakdown of these parts
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Which of the following is the function of a hydraulic pump?
• To provide flow to the hydraulic system • To create the pressure required in a hydraulic system • To control the pressure required in a hydraulic system • To compensate for atmospheric pressure at varying altitudes |
To provide flow to the hydraulic system
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Chemical contamination of hydraulic liquid by oxidation is indicated when the liquid contains which of the following materials?
• Sludge • Asphaitine particles • Organic acids • Each cf the above |
Each cf the above
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All of the following contaminants are abrasive EXCEPT
• lint • sand particles • rust • sludge |
lint
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Which of the following agents, if combined with minute amounts of water found in operating hydraulic systems, does NOT change into hydrochloric acid?
• Chlorinated solvents • Trichlorotrifluoroethane • An approved dry-cleaning solvent • Trichlorofluoromethane |
An approved dry-cleaning solvent
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The ratings of most hydraulic pumps are determined by their
• efficiency • amount of internal slippage • volumetric output at a given pressure • output per unit time |
volumetric output at a given pressure
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The fluid currently being used in a hydraulic system that requires a nonflammable liquid will probably be a
• petroleum-based liquid • synthetic-based liquid • blend of petroleum and vegetable oil • blend of water and oil |
synthetic-based liquid
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Water-based fluids’ resistance to fire depends on the vaporization and smothering effect of steam generated from water.
• True • False |
True
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Trouble develops in a hydraulic system when the fluid becomes contaminated as the result of
• system component deterioration • any action that places foreign matter in the fluid • abrasive wear • friction at hotspots |
any action that places foreign matter in the fluid
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Water contamination of a hydraulic system is NOT a major concern since its presence aids in reducing the flammability of the fluid.
• True • False |
False
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Which of the following statements is/are true concerning synthetic based fluids?
• They will not burn • They are compatible with most commonly used packing and gasket materials • They may contain toxic chemicals • All of the above |
All of the above
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Which of the following is generally the basis for rotary pump classification?
• Type of rotating element • Type of drive • Service application • Shaft position |
Type of rotating element
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Which, if any, of the following statements is true of a screw pump ?
• Its performance is based on the fluid’ s viscosity • It is very efficient • The idler rotors are connected by gears • None of the above |
Its performance is based on the fluid’ s viscosity
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Which of the following components will revolve during the operation of this pump?
• Cylinder block • Slide block • Both 1 and 2 above • Pintle |
Cylinder block
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The rocker arm will be perpendicular to the shaft when the shaft has been rotated how far?
• One-half of a turn • One-quarter of a turn only • Three-quarters of a turn only • Either one-quarter or threequarters of a turn |
One-half of a turn
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The nominal size of pipe whose outside diameter is 1.900 inches is
• 2 • 1 1/2 • 2 ¼ • 1 3/4 |
1 1/2
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Pulsations of fluid flow from a radial-piston pump are much greater if the pump has an even number of pistons than if it has an odd number.
• True • False |
True
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The output of the axial-piston pump is determined by which of the following factors?
• Angle given to the tilting plane • Number of pistons • Length of the drive shaft • Length of the piston rods |
Length of the piston rods
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During nonflow operation of a variable-displacement Stratopower pump, what provides its lubrication?
• Compensator piston • Compensator spring • Drive cam • Bypass system |
Bypass system
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Automatic variation of the volume output of a variable-displacement Stratopower pump is controlled by which of the following factors?
• The position of the rocker arm on the shaft • The pressure in the hydraulic System • Atmospheric pressure • Reciprocating action of the pistons |
The pressure in the hydraulic System
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Which type of gear-type rotary pumps discharges the smoothest fluid flow?
• Crescent • Helical • Spur • Herringbone |
Herringbone
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You must give primary consideration to all but which of the following factors in selecting the lines for a particular fluid power system?
• The material’s outside Diameter • The type of material • The material’s inside diameter • The material’s wall thickness |
The material’s outside Diameter
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What component of a Stratopower pump holds the pistons in constant contact with the mechanical drive mechanism?
• Piston return spring • Wobble plate • Check spring • Creep plate |
Wobble plate
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Why are helical gear pumps classified as external gear pumps?
• Both sets of teeth project inward toward the center of the gears • The teeth of the interior gear project inward toward the center of the gears, and the teeth of the exterior gear project outward from the center of the gears • Both sets of teeth project outward from the center of the gears • The teeth of the interior gear project outward from the center of the gears, and the teeth of the exterior gear project inward toward the center of the gears |
Both sets of teeth project inward toward the center of the gears
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This type of pump is used in some aircraft hydraulic systems to provide a source of hydraulic power for what purpose(s)?
• Emergencies • Testing certain subsystems during preventive maintenance • Determining the causes of malfunctions in certain subsystems • All of the above |
All of the above
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Which of the following components of a radial-piston pump is connected to the cylinder block?
• Piston • Rotor • Drive shaft • Pintle |
Rotor
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The pumping action of this pump is obtained by which of the following actions?
• Moving the rotor and reaction ring to provide unequal piston travel radially around the cylinder block • Rotating the pintle at the center of the cylinder block • Moving the cylinder block off center from the axis of the pintle • Positioning the sliding block to provide unequal travel of the pistons in the cylinder block |
Moving the rotor and reaction ring to provide unequal piston travel radially around the cylinder block
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Replacement of a piece of tubing with one having a smaller inside diameter will result in which of the following conditions?
• Fluid heating • Turbulent fluid flow • System power loss • All of the above |
All of the above
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This connector is attached to the piping by welding, brazing, tapered thread, or rolling and bending.
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Flange
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This connector connects subassemblies in some fluid power systems, especially in high-pressure systems that use pipe for the fluid lines
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Welded
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This connector is commonly used for joining nonferrous piping in the pressure and temperature range where its use is practical
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Brazed
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True or False. The fitting of a flared connector should be made of material having greater strength than that of its sleeve and nut and of the piping
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False
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A universal fitting is one that can be?
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positioned to the angle required for the installation
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This connector is tightened 1/6 turn past the specified torque.
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steel flared type
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This connector may not be tightened past the specified torque.
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Aluminum alloy flared type
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This connector must be turned with a wrench 1/6 turn past handtight
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flareless type
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Manifolds are ued in the pressure supply and/or return lines of fluid power systems to perform what functions?
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conserve space, reduce joints, and eliminate piping
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In long pieces of tubing or pieces bent to a complex shape, rust and scale can be removed by what process?
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pickling
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Valves are used to control what in fluid power systems?
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direction of fluid flow, fluid pressure, and fluid flow
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Its flow is controlled by raising or lowering discs or wedges.
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globe
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Flow or no-flow through it is controlled by turning the valve shaft one-quarter turn.
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ball
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Certain types are used as variable restrictors
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needle
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True or False. Gate valves are suitable for use as throttling valves because they close in small increments.
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False
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The fitting of a flared connector should be made of material having greater strength than that of its sleeve and nut and of the piping.
• True • False |
False
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Which of the following metals may be used to provide a strong, inexpensive pipe or tubing capable of withstanding high pressures and temperatures?
• Stainless steel • Copper • Steel • Aluminum |
Steel
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Which of the following statements is NOT correct for cutting tubing with a hacksaw?
• A fine-tooth hacksaw of 48 teeth per inch could be used • When you clamp the tubing in a vice, tighten the vice until the tubing is just starting to hold without collapsing • All hacksaw marks must be removed by filing |
A fine-tooth hacksaw of 48 teeth per inch could be used
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Bends in piping serve to absorb vibration and to compensate for thermal expansion and contraction.
• True • False |
True
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The determining factor for the radius of the bend to be made in a pipe is the pipe’s
• outside diameter • wall thickness • length • inside diameter |
length
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A universal fitting is one that can be
• adapted to operate with any size tubing • positioned to any angle in any plane • positioned to the angle required for the installation • routed through a bulkhead |
positioned to the angle required for the installation
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What parts of the hand tube bender are used to obtain the correct bend radius and the desired bend angle on tubing?
• The clip and the slide bar • The forming bar and the slide Bar • The radius block and the slide bar • The radius block and the clip |
The radius block and the slide bar
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The flexible hose that is inert to all fluids presently used and that does not absorb water is composed of what material?
• Synthetic rubber • Natural rubber • Rubber impregnated cotton or Nylon • PTFE |
PTFE
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The threads of newly threaded pipe do not corrode if the fittings cover all of the exposed threading.
• True • False |
True
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What is the size of No. 4 rigid tubing , and where is the measurement taken?
• 1/4 inch, outside diameter • 4/16 inch, inside diameter • 0.040 inch, wall thickness • 0.004 inch, wall thickness |
4/16 inch, inside diameter
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What is the schedule 40 wall thickness of pipe with a nominal pipe size of 2 inches?
• 0.436 in. • 0.218 in. • 0.308 in. • 0.154 In. |
0.218 in.
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Coarse-toothed hacksaw blades are preferred for cutting tubing because they cut faster and are less liable to choke up with the chips.
• True • False |
False
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Flexible hose should be used in locations where it will be subjected to
• intense heat • severe vibration • an oily environment • excessive abrasion |
severe vibration
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The use of threaded connectors is generally limited to low-pressure systems.
• True • False |
False
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Quick-disconnect couplings are provided with an automatic shutoff feature which prevents loss of fluid from the system or entrance of foreign matter into the system when they are disconnected.
• True • False |
True
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The size of flexible hose is designated In what increments measured at what place?
• Sixteenths-inch, Inside Diameter • Thousandths of an inch,” outside diameter, • Thousandths of an inch, inside diameter • Sixteenths-inch, outside, diameter |
Sixteenths-inch, Inside Diameter
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A characteristic of flexible hose is that under pressure it will
• contract in diameter and expand in length (your response) • retain its manufactured dimensions • expand in both diameter and length • expand in diameter and contract in length |
expand in diameter and contract in length
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What type of valving element is most commonly used in directional control applications?
• Rotary spool • Poppet • Sliding spool • Ball |
Poppet
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What type of check valve permits free flow of fluid in one direction and a limited flow of fluid in the opposite direction?
• Swing • Vertical • Orifice • Ball |
Orifice
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If the input pressure of the inlet port is less than the setting of the pressure reducing valve, what should be the respective positions of the poppet valve and the spool valve?
• Closed, closed • Closed, open • Open, closed • Open, open |
Open, closed
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Approximately how far must the handwheel of a globe valve be turned toward the closed position after the valve has been fully opened?
• 1/2 turn • 1/4 turn • 3/4 turn • 7/8 turn |
1/2 turn
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Chatter in a relief valve is the result of
• too much difference between opening and closing pressures of the valve • rapid opening and closing of the valve as it ‘hunts- above and below a set pressure • concurrent operation of the small relief valve and the main relief valve • improper seating of the valve Element |
rapid opening and closing of the valve as it ‘hunts- above and below a set pressure
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If a fluid power system uses two or more relief valves, they must all be the same size.
• True • False |
True
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Chatter of a pressure regulator may be prevented by
• using a constant displacement pump • maintaining a very small differential pressure • making cutout (closing) pressure higher than cutin (opening) pressure • installing a snubber in the fluid supply line |
maintaining a very small differential pressure
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A hydraulic pressure regulator does which of the following?
• Maintains the system pressure between two predetermined levels • Maintains the system pressure below a predetermined pressure level • Maintains the system pressure above a predetermined pressure level • Regulates the quantity of fluid flow in the system |
Maintains the system pressure between two predetermined levels
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Gate valves are suitable for use as throttling valves because they close in small increments.
• True • False |
False
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A poppet is used as the valving element for which of the following fluid power valve applications?
• Flow control • Pressure control • Directional control • All of the above |
All of the above
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What type of flow control valve makes the most suitable throttle valve?
• Globe • Plug • Gate • Needle |
Needle
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Check valves usually contain what types of valving elements?
• Sleeve and poppet • Rotary spool and sliding Spool • Ball and poppet • Ball and cone |
Ball and cone
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When the system pressure Increases above the pressure to which the valve is set, the main valve opens
• every time the pilot valve opens but at a predetermined time interval afterward • independently of the pilot valve • only after the system pressure increases to more than can be relieved by the pilot valve • concurrently with the pilot valve |
only after the system pressure increases to more than can be relieved by the pilot valve
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Relief valves are used for which of the following functions?
• To prevent pressure from rising above a predetermined level • To maintain pressures above a predetermined level • To maintain fluid flow below a predetermined rate • To prevent thermal expansion of the fluids |
To prevent pressure from rising above a predetermined level
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A restriction in the drain would cause the outlet port pressure to
• increase • remain the same • pulsate • decrease |
decrease
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What is the operational state of the regulator when the system pressure is less than that required to operate one of the activating units in the system?
• The pilot valve is seated, the check valve is unseated, and fluid is flowing into the system • The check valve is unseated, the pilot valve is seated, and fluid is flowing into the return line • The check valve is unseated, the pilot valve is unseated, and fluid is flowing into the system and into the return line • The pilot valve is unseated, the check valve is seated, and fluid is flowing into the system |
The check valve is unseated, the pilot valve is unseated, and fluid is flowing into the system and into the return line
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The globe valve gets its name from the globular shape of its body, a shape that is unique to this valve.
• True • False |
True
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After the main valve has relieved the system and when pressure returns to normal, what does pilot valve do?
• It closes first and allows pressure to equalize above and below the main piston • It closes simultaneously the main valve • It remains open until after the main valve closes • It closes first and causes pressure above the main piston to force the main valve closed |
It closes first and causes pressure above the main piston to force the main valve closed
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For the pressure-controlled sequence valve to operate properly, the tension of the spring must be sufficient to hold the piston in the closed position against pressure required to operate the primary unit.
• True • False |
False
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In long pieces of tubing or pieces bent to a complex shape, rust and scale can be removed by what process?
• Scraping • Degaussing • Sandblasting • Pickling |
Sandblasting
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What is/are used when the O-ring installation requires spanning or inserting through sharp threaded areas, ridges, slots, and edges?
• A rolling motion of the O-ring • O-ring expanders • O-ring entering sleeves • A light coating of the threads with MIL-S-8802 |
O-ring entering sleeves
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What is the basis for computing the age of an O-ring’?
• Replacement schedule • Service life • The cure date • Operational conditions |
The cure date
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Cork is suitable for use as gaskets because of which of the following characteristics?
• Its resiliency • Its flexibility • Its compressibility • All of the above |
Its compressibility
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What device is used to prevent O-ring seal extrusion under pressure?
• Flange packing • Backup ring • Gasket • Cup packing |
Backup ring
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When the pilot chamber of the three-way, poppet-type, normally closed directional control valve is pressurized, fluid flows from the actuating cylinder through the valve and out the exhaust port .
• True • False |
True
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Backup rings made from which of the following materials are the most widely used?
• Tetrafluorethylene (TFE) • Cork • Bakelite • Leather |
Tetrafluorethylene (TFE)
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Which four-way valves are actuated by cams?
• Rotary spool • Poppet • Sliding spool • All of the above |
Poppet
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What is the age of deterioration of TFE backup rings?
• 3 years • TFE does not deteriorate • 5 years • 1 year |
TFE does not deteriorate
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Although it has many of the characteristics required in an effective seal , which of the following materials is not used as packing material in a system in which petroleum-base fluid is used?
• Synthetic rubber • Natural rubber • Asbestos • Cork |
Natural rubber
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Which of the following materials should NOT be used to fabricate tools for use in removing and installing O-ring and backup rings?
• Wood • Steel • Brass • Phenolic rod |
Brass
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You are reassembling a vital component which uses a copper sealing ring and discover there is not a new replacement ring. Which, if any, of the following steps should you take?
• Reinstall the old ring after inspecting it for damage • Install an O-ring that is compatible with the fluid used in the system • Reinstall the old ring after it has been annealed • None of the above |
Reinstall the old ring after it has been annealed
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The term “sealing devices” is a classification applicable to packing materials used to provide an effective seal between which of the following parts?
• Two moving parts • Two stationary parts • A moving part and a stationary part • All of the above parts Combinations |
All of the above parts Combinations
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No internal leakage should be allowed to occur within a hydraulic power system because of the resulting loss in system efficiency.
• True • False |
True
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Which of the following factors is/are used in determining the material used as a sealing device for a particular application?
• Location of the seal • Storage of the seal • Both 1 and 2 above • Type of motion |
Both 1 and 2 above
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Why are O-rings sometimes rolled on a cone or dowel?
• To condition them before installation • To expose the manufacturer’s identification code • To determine their breaking point • To expose and stretch the inner diameter surface for inspection |
To expose and stretch the inner diameter surface for inspection
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Which type of valve is considered most trouble free of all four-way valves?
• Rotary spool • Poppet • Cam operated • Sliding spool |
Sliding spool
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What is the first step in replacing an O-ring in a disassembled fluid power system component?
• Identify the ring’s size and material • Lubricate the O-ring groove and all surfaces over which the ring must slide • Inspect the ring for cuts, nicks, and flaws • Install felt washers on both sides of the ring |
Lubricate the O-ring groove and all surfaces over which the ring must slide
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A torn O-ring package is properly secured with which of the following materials?
• Moistureproof glue • Pressure-sensitive, moistureproof tape • Outer covering of moistureproof paper • Staples |
Pressure-sensitive, moistureproof tape
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The reservoir serves the primary function of storing the hydraulic fluid required by the system, Which of the following secondary functions does it also serve?
• Separates air from the system • Dissipates heat • Traps foreign matter • All of the above |
Dissipates heat
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Which of the following statements is incorrect concerning U-cups and U-packings?
• They are usually made of different materials • They are interchangeable • They have cross sections resembling the letter U • They both seal on the OD and the ID |
They are interchangeable
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Gauges having bellows elements are used only for pressure indicating.
• True • False |
False
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Which of the following statements best describe(s) the advantage a vented tailrod accumulator has over a floating piston accumulator?
• The tailrod allows the accumulator to be used as a hydraulic actuator, thus eliminating the number of system components requiring maintenance • The vented tailrod accumulator has the space between the piston seals vented to the atmosphere, causing air or oil leakage past the seals to be apparent • Both 1 and 2 above • The vented tailrod accumulator has a gauge that provides a quick indicationof the amount of fluid in the accumulator |
The vented tailrod accumulator has a gauge that provides a quick indicationof the amount of fluid in the accumulator
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In the operation of pressure gauges within a hydraulic system, what does a gauge snubber do?
• Dampens out system pressure surges and oscillations to the gauge, thereby preventing internal damage • Prevents hydraulic pressure indicators from oscillating, thereby ensuring an accurate system pressure reading • Both 1 and 2 above • Meters the flow of pressurized hydraulic fluid from the gauge or transmitter, thereby preventing internal damage |
Dampens out system pressure surges and oscillations to the gauge, thereby preventing internal damage
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Which of the following is NOT a function of pressure switches?
• Indicating pressure • Energizing an auxiliary control system • De-energizing an auxiliary control system • Signaling a visual warning or audible alarm when a preset pressure is reached |
Signaling a visual warning or audible alarm when a preset pressure is reached
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Why must the reservoir of an aircraft designed for high altitude operations be pressurized?
• To use atmospheric pressure to assist fluid flow • To vent the system during periods of high fluid demand • To maintain a net positive suction head to the pump • To prevent the fluid from congealing at high altitudes |
To use atmospheric pressure to assist fluid flow
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A duplex Bourdon gauge is composed of
• one mechanism with one indicator showing current pressure and a second indicator showing the maximum pressure reached • one indicator dependent upon both of two separate mechanisms • one mechanism with one indicator showing pressure in pounds per square inch (psi) and a second indicator showing the load on a ram in tons • two separate and independent mechanisms and indicators |
two separate and independent mechanisms and indicators
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A pressurized reservoir may be Instead at a level below the pump suction and still maintain a positive flow of fluid to the pump.
• True • False |
True
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A Bourdon-tube differential pressure gauge is composed of
• one indicator dependent upon both of two separate mechanisms • one mechanism with one indicator which can register pressure either above or below atmospheric pressure • one mechanism with one indicator showing current pressure and the second indicator showing the maximum pressure reached • two separate and independent mechanisms and indicators |
one mechanism with one indicator showing current pressure and the second indicator showing the maximum pressure reached
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Distant-reading thermometers operate similarly to Bourdontube pressure gauges.
• True • False |
True
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Which of the following gauges can be used to measure the differential pressure across a strainer?
• Duplex gauge • Differential pressure gauge • Both 1 and 2 above • Compound gauge |
Duplex gauge
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What is the maximum length, in feet, of the capillary tube of distant-reading thermometers?
• 100 • 125 • 75 • 50 |
125
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A change in which of the following properties is the basis of operation of the bimetallic thermometer?
• Chemical • Electrical • Physical • All of the above |
Physical
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Which of the following statements describe(s) how an excessive amount of gas is prevented from being entrained In direct contact accumulators?
• Safety fluids are used in this type of accumulator • The fluid port is located at the bottom of the accumulator • These accumulators are generally not used for pressures over 1200 psi • All of the above |
These accumulators are generally not used for pressures over 1200 psi
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The pressure switch sensing element operates on the same principle as the Bourdon-tube pressure gauge.
• True • False |
False
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The baffles In a reservoir serve which of the following functions?
• Dissipate heat • Trap foreign matter • Separate air form the system • All of the above |
Separate air form the system
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Why does a bladder-type, air operated accumulator have a very high volumetric efficiency?
• The bladder is larger top and the rubber is thinner at the top • The bladder is larger top and the rubber is at the at the bottom’ • The bladder is larger bottom and the rubber is thinner at the bottom • The bladder is larger bottom and the rubber is thinner at the top |
The bladder is larger top and the rubber is at the at the bottom’
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What type of seal is least desirable and is used only where there is not sufficient space for a U-ring packing or a V-ring packing?
• Flange • Cup • O-ring • Quad-Ring |
Cup
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