Induced draft fans provided in large thermal power plant boilers have __________ blades.
Forward curved
Backward curved
Double curved
Radial or straight
Correct Answer :
B. Backward curved
Related Questions
In a drilling process, the metal is removed by both shearing & extrusion. General purpose drills are made of
Stainless steel
Mild steel
High speed steel
High carbon steel
Plastics as a material of construction suffer from the drawback of low
Machinability
Density
Strength
Plastic deformation
Function of gear box is to
Reduce the speed
Obtain variable speed
Increase the speed
Produce high torque
__________ is the hardest material out of the following.
Boron carbide
Tungsten carbide
Hardened steel
Silicon carbide
A steam carrying 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
Increase
Decrease
Remain unaffected
May increase or decrease; depends on the thickness of each layer
Lap joints are preferred over butt joints in soldering/brazing, because these joints are
Weaker in tension but stronger in shear
Weaker in shear but stronger in tension
Stronger in both shear and tension
The lap joints are easily made
Isotropic materials have the same __________ in all directions.
Induced stresses
Density
Elastic properties
Thermal properties
__________ rubber is generally used for making 'O' rings used for vacuum sealings.
Natural
Neoprene
Butadiene
Nitrile
Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of
Grashoff number
Grashoff number & Reynolds number
Reynolds number
Grashoff number & Prandtl number
__________ of air does not increase with increase in temperature.
Density
Thermal diffusivity
Viscosity
Thermal conductivity
Corrosion is
A physical phenomenon
A chemical phenomenon
Same as erosion
An uncontrollable phenomenon
Batch process is preferred over continuous process, when the
Product yields and quality cannot be achieved in continuous process, because of long residence time
Sales demand of product is not steady
Same equipment cannot be used for several processes of the same nature
All (A), (B) & (C)
Air-petrol ratio in an automotive petrol engine is around
14 : 1
22 : 1
25 : 1
4 : 1
Pick out the wrong statement.
Seam welding, projection welding & spot welding are the classification of electrical resistance welding
Electrode tip in spot welding is of copper and the tip diameter should be equal to t (where, t = plate thickness to be welded)
In spot welding, two pieces to be joined are overlapped and placed between two electrodes
Mild steel sheet cannot be spot welded
In a neutral solution
H+ ions are absent
OH- ions are absent
Both H+ and OH- ions are present in very small but equal concentration
None of these
The type of pump used for lifting large quantity of sewage is a __________ pump.
Gear
Centrifugal
Reciprocating
Plunger
Cobalt - 60 is used as a source of __________ in medical therapy & industrial radiography.
X-rays
γ-rays
α-rays
β-rays
At absolute zero temperature, for any reaction involving condensed phases
Δ G° = 0 , Δ H° = 0
Δ H° = 0 , Δ S° = 0
Δ S° = 0 , Δ E° = 0
Δ S° = 0 , Δ Cp° = 0
Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the
Length of the pipe
Diameter of the pipe
Density of the fluid
Velocity of the fluid
Which of the following is an example of stress corrosion?
Season cracking of brass
Caustic embrittlement of steel
Both (A) & (B)
Neither (A) nor (B)
A spring material should have low
Elastic limit
Deflection value
Fatigue resistance
None of these
Recrystallisation temperature of steel is __________ °C.
50
300
500
800
Pick out the correct statement about the condensation.
Filmwise condensation gives a lower heat transfer rate than the dropwise condensation
Suitable coating or vapour additive is used to promote film wise condensation
If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it
Reynolds number of condensing liquid is based on its mass flow rate
Brass parts with high residual tensile stress at the surface are susceptible to season cracking (i.e. spontaneous cracking occuring on exposure to atmospheric corrosion), if its zinc percentage is more than
5
10
20
35
The life of a ball bearing is inversely proportional to
(Load)1
(Load)2
(Load)3
(Load)0.33
The most serious manufacturing defect from fracture toughness point of view is
Surface roughness
Pores
Spherical inclusion
Crack
Steels with high carbon equivalent have poor Weldability, because in these steels during welding
Carbon and other alloying elements get oxidised from the weld pool
Excessive ferrite forms in the heat affected zone leading to poor toughness of the weld
Martensite forms in the heat affected zone leading to poor toughness/ductility of the weld
Segregation of carbon and other element occurs in the weld pool leading to poor properties of the weld
Copper deposits are found in India at the following location:
Kudremukh
Kolar
Khetri
Ramagundam
Multistage compression of air as compared to single stage compression offers the advantage of
Power saving per unit weight of air delivered
Moisture elimination in the inter-stage cooler
Increased volumetric efficiency
All (A), (B) & (C)
The size of the tetrahedral void in the closest packing of atoms is __________ that of the octahedral void.
Equal to
Greater than
Less than
Either (A), (B) or (C); depends on the size of atom