Insulating refractories should have

Directions : In each of the following questions a statement is given, followed by two conclusions. Give answer :

Statement : The integrated steel plants in India would no longer have to depend on imports for continuous casting refractories.

Assumptions :
I. Continuous casting refractories are needed by India.
II. Continuous casting refractories are in demand.

A

Only assumption I is implicit

B

Only assumption II is implicit

C

Either I or II is implicit

D

Neither I nor II is implicit

E

Both I and II are implicit

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

Faster rate of drying of moulded refractories results in high __________ of refractories.

A

Green strength

B

Voids

C

Shrinkage

D

Both B and C

Silica refractories are also known as ______ refractories.

A

Acid

B

Basic

C

Neutral

D

Magnesia

Basic refractories are costlier than acid refractories.

A

True

B

False

Porosity is induced in insulating refractories by adding

A

Powdered naphthalene

B

Ammonium chloride/sulphate

C

Calcium phosphate

D

All of the above

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

Refractories used in/for __________ should have low thermal conductivity.

A

Coke ovens

B

Insulation

C

Regenerators

D

Muffle furnaces

Furnace atmosphere for softening temperature determination of refractories (in which segar cones are placed) should be

A

Oxidising

B

Neutral

C

Either A or B

D

Neither A nor B

The insulating material for a cable should have

A

Low cost

B

High dielectric strength

C

High mechanical strength

D

All of the above

Insulating refractories should have

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