3071. Safe condition for storage of high V.M. bituminous coal is that
Height of the coal heap should be < 3 metres
Maximum 200 tons should be stored in a heap
Both A and B
Neither A nor B
✅ The correct answer is option C.
3030. High refractorinness of refractory bricks means, that it has a
high spalling resistance.
low spalling resistance.
high resistance to fusion.
low porosity.
✅ The correct answer is option C.
3040. Magnesite refractories are generally not used in the
electric furnace walls.
steel melting furnace.
open hearth furnace.
burning zone of cement kilns.
✅ The correct answer is option B.
3046. Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.
1800
2200
2400
2700
✅ The correct answer is option D.
3055. An indication of degree of firing in silica brick is its
specific gravity
fusion point
RUL
none of these
✅ The correct answer is option A.
3060. Thermal conductivity of refractory bricks
increases with decrease in porosity.
decreases with decreases in porosity.
is independent of its porosity and is maximum for insulating bricks.
increases with the amount of air entrapped in pores.
✅ The correct answer is option A.
3027. With increase in the porosity, thermal spalling resistance of fireclay brick
increases
decreases
remains same
may increase or decrease
✅ The correct answer is option A.
3031. Which is an acidic refractory ?
Magnesite
Dolomite
Fireclay
Chrome magnesite
✅ The correct answer is option C.
3036. Refractory bricks having lower porosity have
high insulating properties
low heat capacity
low thermal conductivity
greater strength
✅ The correct answer is option D.