Related Questions

A steam carraying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will
A Increase
B Decrease
C Remain unaffected
D May increase or decrease; depends on the thickness of each layer
An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture?
A Cork
B Saw dust
C Sand
D Chemically prepared foam
Out of the following themocouple wire insulating material, the highest temperature rating is for
A Teflon
B Ceramic fibre
C Asbestos
D Fibre glass
Which of the following is the most widely used insulating material for steam carray-ing pipelines?
A Ceramic fibre blanket
B Glass wool and 85% magnesia
C Vermiculite
D Slag wool
Which of the following is the most widely used heat insulating material for pipelines carrying steam?
A Tar dolomite bricks followed by asbestos
B Fireclay refractory followed by aluminium sheet
C Cotton followed by aluminium foil
D 85% magnesia cement and glass wool
Which is not a natural insulating material?
A Diatomaceous earth/kieselgur
B Asbestos
C Vermiculite
D None of these
The insulating material for a cable should have
A Low cost
B High dielectric strength
C High mechanical strength
D All of the above
The insulating material for cables should
A Be acid proof
B Be non-inflammable
C Be non-hygroscopic
D Have all above properties
Surface resistance of an insulating material is reduced due to the
A Smoky and dirty atmosphere
B Humidity in the atmosphere
C Both A and B
D Neither A nor B
If an insulating material is operated beyond the maximum allowable temperature, its life is
A drastically increased
B drastically reduced
C unaffected
D none of the above

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