This set of Foundry Questions and Answers for Entrance exams focuses on “Gas Fired Pit Furnace”.
1. High atmosphere circulation is attained in a pit furnace.
a) True
b) False
View Answer
Explanation: The circulation fan is mounted centrally in the lid. The retort is formed as a cylinder with a flange on top. On this flange, there is a circular cooling tube. Thus, highly efficient atmosphere circulation system is present in the Pit furnace.
2. _________ is used for insulation in Pit furnaces.
a) Polymer fiber
b) Ceramic fiber
c) Metal matrix reinforced fiber
d) Plastic fiber
View Answer
Explanation: The ceramic fiber is lined inside the furnace body. The insulation is provided to save the heat from going out. It acts as an energy saving shield and reduces operation costs.
3. The coke in the pit furnace burns completely.
a) True
b) False
View Answer
Explanation: The coke bed which is formed in the furnace is ignited and allowed to burn. Once it reaches the state of maximum combustion, coke from the centre of coke bed is shifted towards sides to make space for crucible containing the metal charge.
4. Pit Furnace is used in ___________
a) Permanent mould
b) Shell mould
c) Skin dried mould
d) Air dried mould
View Answer
Explanation: Pit furnace has a limited capacity. It is used to melt a certain low amount of metal to produce castings. Only small castings can be produced. Hence, it is often used with permanent moulds and die casting machines.
5. Gas Pit furnaces are situated in long heating tubes.
a) True
b) False
View Answer
Explanation: The furnace is constructed in a pit and it extends to floor level or a level little above the ground. This manner provides efficient loading and minimal distortion.
6. ________ is used to fuel gas furnace.
a) Marsh gas
b) Carbon-dioxide
c) Ammonia gas
d) Natural gas
View Answer
Explanation: The natural gas is widely available and can be used for the gas furnace due to its easy combustion method. As a gas furnace have a burner in the furnace it is fuelled by natural gas.
7. _____________ is used to accelerate the metal cooling in gas pit furnace.
a) Coolant
b) Fans
c) Blower
d) Cannot be determined
View Answer
Explanation: The draft of the air through furnace may be a natural draft for low melting temperature metals but this force draft can be used to accelerate the melting process with the help of the blower.
8. Large compositional change occurs in the charge while using the Gas pit furnace.
a) True
b) False
View Answer
Explanation: Since the molten metal does not come in contact with the fuel, there is no pick up of the elements by the metal from the coke and hence a very little compositional change occurs in the metal charge of the gas pit furnace.
9. The gas pit fire furnace is fired with gun powder.
a) True
b) False
View Answer
Explanation: The gas pit furnace is fired with coke, oil or gas. For maximum amount of times, it is seen to be fired with coke. Enough coke is packed round so as to melt and superheat the metal charge.
10. The gas fired pit furnace is used for tempering and normalizing.
a) True
b) False
View Answer
Explanation: The gas fired pit furnace is used for tempering, normalizing and solution treatment which is used in aluminum and in annealing. It is used for such process as it is a standard in various industries for fast heat up and to obtain uniformity in temperature very fast.
Sanfoundry Global Education & Learning Series – Foundry and Forging.
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