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
Low thermal conductivity of heat insulating materials is due to its
A Dense structure
B High proportion of air space
C High specific heat
D None of these
Which of the following insulating materials can withstand the highest temperature safely?
A Cellulose
B Asbestos
C Mica
D Glass fibre
A steam pipe is to be insulated by two insulating materials put over each other. For best results
A Better insulation should be put over pipe and better one over it
B Inferior insulation should be put over pipe and better one over it
C Both may be put in any order
D Whether to put inferior OIL over pipe or the better one would depend on steam temperature
Effect of moisture on the insulating materials is to
A Decrease dielectric constant
B Decrease dielectric strength
C Decrease insulation resistance
D Increase dielectric loss
E All of the above
Insulating materials have the function of
A Preventing a short circuit between conducting wires
B Preventing an open circuit between the voltage source and the load
C Conducting very large currents
D Storing very high currents
A steam pipe is to be lined with two layers of insulating materials of different thermal conductivities. For the minimum heat transfer,
A The better insulation must be put inside
B The better insulation must be put outside
C One could place either insulation on either side
D One should take into account the steam temperature before deciding as to which insulation is put where
A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place
A The better insulation material should be put just next to pipe (i.e., inside)
B The better insulating material should be put outside
C Either of the insulating material could be put on either side
D Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)
Out of the following themocouple wire insulating material, the highest temperature rating is for
A Teflon
B Ceramic fibre
C Asbestos
D Fibre glass

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