The most detrimental impurity in high pressure boiler feed water is
Suspended salt
Dissolved salt
Silica
Turbidity
Correct Answer :
C. Silica
Related Questions
Electrometallurgical methods of metal extraction is normally used for those metals
Whose oxide/ore is not reduced by carbon
Which fall in the category of alkali & alkaline earth metals
Which stands higher in the electrochemical series of the metal
All (A), (B) & (C)
Hydrogen can be
Used in I.C. engines as fuel
Liquefied & stored under cryogenic conditions
Produced by electrolysis of water
All (A), (B) & (C)
Principal alloying elements of cast tool alloys which have very high wear resistance & high temperature strength are
Cobalt, chromium & tungsten
Cobalt, chromium & nickel
Molybdenum, tungsten & chromium
Cobalt, zirconium & molybdenum
Strain hardening effect in a metal subjected to cold working is due to the __________ mechanism.
Fracture
Dislocation
Slip
Twinning
As per international norms, the maximum permissible value of noise level in the industrial environment is __________ decibels as measured at a distance of 1.5 metres from the source of noise.
110
85
60
45
Speisses is a mixture of the following:
Arsenides of heavy metals
Antimonides of heavy metals
Arsenides & antimonides of heavy metals
Iron, cobalt and nickel
The only suitable method for hardening the low carbon steel is case hardening. Which of the following is a case hardening process?
Cyaniding
Sherardizing
Spheroidising
None of these
What is the value of included angle of a triangular notch for maximum discharge?
30°
60°
90°
120°
Air-petrol ratio in an automotive petrol engine is around
14 : 1
22 : 1
25 : 1
4 : 1
Flue gases pass through the following boiler accessories in a high pressure natural circulation boiler.
A. Induced draft fan
B. Economiser
C. Air preheater
D. Steam superheater Which of the following gives the correct sequence of flow of the flue gases through the above mentioned boiler accessories?
A, C, B, D
D, B, C, A
D, C, B, A
D, A, B, C
A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about __________ °C.
370
340
320
300
Carbon is present in the form of __________ in grey cast iron.
Spheroids
Nodular aggregates of graphite
Flakes
Cementite
Hot & cold working of material causes its __________ deformation.
Visco-elastic
Isotropic
Elastic
Plastic
__________ can replace tungsten in high speed steel.
Chromium
Vanadium
Cobalt
Molybdenum
One of the methods of purification of leach liquor is ion exchange, which involves
Exchange between two liquid phases
Exchange between a gaseous phase and a liquid phase
Exchange between a liquid phase and an organic resin phase
Exchange between a solid phase and a gas phase
Corrosion of metals cannot be prevented by its
Tempering
Chromising
Aluminising
Alloying
Pressure exerted by a liquid depends upon its
Surface tension
Density
Viscosity
Buoyancy
In inventory control theory, the economic order quantity (EOQ) is the
Lot size corresponding to break even analysis
Average level of inventory
Optimum lot size
None of these
All of the following alloying elements of steel increases hardness but sacrifice ductility, except
Nickel
Vanadium
Molybdenum
Chromium
What is the range of tempering temperature (°C) for most of the materials?
75-100
200-300
350-450
500-600
A dummy activity is used in PERT network to describe the
Precedence relationship
Resource idleness
Resource restriction
Necessary time delay
The most important consideration in value engineering is the
Profit maximisation
Customer satisfaction
Cost reduction
Process improvement
The Al2O3 content of cryolite in Hall- Heroult cell is maintained between __________ percent.
2-5
18-20
12-15
6-12
Quartz is a __________ material.
Diamagnetic
Ferromagnetic
Ferroelectric
Piezoelectric
Out of the following, the __________ pipe has the least corrosion resistance.
Mild steel
Copper
Cast iron
Wrought iron
Good design of the casing of a centrifugal pump aims at minimising the
Cavitation
Frictional losses
Kinetic energy loss
Static head
__________ has a negative co-efficient of linear expansion.
Iron
Copper
Rubber
Nickel
A cylindrical rod subjected to a tensile strain within the elastic limit undergoes a volume change. If the volume strain is equal to half the tensile strain, then the Poisson's ratio of the rod is
0
0.33
0.44
0.25
Stainless steel is welded with difficulty because of
Its high melting temperature
Chances of cracking
Oxide film formation
Chromium carbide formation
The capacity of a spring to store energy is called the spring form co-efficient. Stiffness of a spring is measured by the
Ability to absorb shock
Capacity to store energy
Ratio of the wire & coil diameters
Load to produce unit deflection