MCQ ON Unfired Pressure Vessels,Oil Seals & Wire Ropes
An unfired pressure vessel is used to carry stem, gases or fluids at pressure
a) Less than atmospheric pressure
b) Greater than atmospheric pressure
c) Equal to atmospheric pressure
d) None of the mentioned
Class 1 pressure vessels are used to contain
a) Lethal substances
b) Light duties applications
c) None of the listed
Explanation: Class 1 pressure vessels are used exclusively for lethal substances. LPG doesn’t fall in the category of lethal substances.
An oil seal is a mechanical device made of elastic material which is used to prevent leakage of fluid between two machine components.
Explanation: It is made of elastomer material.
Does oil seal consist of any spring in its structure?
Explanation: It consist of garter spring which exerts a radial pressure on the rotating shaft and prevents leakage.
Which of the following isn’t true about oil seals?
b) Can be used over a wide range of lubricating oils
c) Can’t tolerate misalignment
d) All of the mentioned
Explanation: Oil seals can tolerate the misalignment to some extent.
If magnitude of contact pressure between sealing lip and rotating shaft is very high then
a) There is excessive friction
b) High temperature
c) Rapid wear
d) All of the listed
Explanation: With high pressure, friction increases leading to high temperatures and increasing wear.
Wire ropes have
a) High strength to weight ratio
b) Solent operation even at high velocities
c) Greater reliability
d) All of the mentioned
Explanation: All of the listed are true for wire ropes.
Wire rope specified as 8×10. Calculate the number of strands.
Explanation: First number indicates number of strands.
Wire rope is specified as 8×10. Calculate the number of steel wires in each strand.
Explanation: Second number represents the number of steel wires in each strand.
If the wires in the strand are twisted in the same direction as the strands, then rope is called a _____ lay rope.
b) Regular Lay
d) None of the listed
Explanation: The lay of the rope tells the manner in which the wires are helically laid into strands and strands into rope. Same direction is indicated by Lang’s lay.
Which among regular lay and Lang lay are popular?
a) Regular Lay
b) Lang Lay
c) Both are equally used
d) Can’t be stated
Explanation: In regular lay ropes, there is a balance resulting from opposite direction of twisting the strands to that of the wires.
In Lang lay ropes, both inner and outer wires are bent on same arc of radius.
Explanation: Due to same direction of rotation, outer wires are bent on an arc of larger radius.