Description : Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity? (A) Sphere (B) Cube (C) Cylinder (L/D = 1) (D) Raschig rings
Last Answer : (A) Sphere
Description : Sphericity of raschig ring (whose length and diameter are equal) is (A) > 1 (B) < 1 (C) 1 (D) 2
Last Answer : (C) 1
Description : The most common packing used in industrial operations is __________ rings. (A) Raschig (B) Lessing (C) Cross-partition (D) Single spiral
Last Answer : (C) Cross-partition
Description : Use of raschig rings in place of crushed stones as packing in packed beds (other things being same) (A) Increases pressure drop, increases surface area (B) Increases pressure drop, decreases ... (C) Decreases pressure drop, increases surface area (D) Decreases pressure drop, decreases surface area
Last Answer : (C) Decreases pressure drop, increases surface area
Description : Diameter of raschig rings used in packed tower in industry is normally around __________ inches. (A) 2 (B) 8 (C) 12 (D) 18
Last Answer : (A) 2
Description : Pick out the correct statement. (A) Fanning friction factor is inversely proportional to Reynolds number always (B) The property of a randomly packed bed (with raschig rings) is given by the ratio of the ... the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow
Last Answer : (D) Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow
Description : Which of the following ceramic packing materials is the costliest of all? (A) Berl saddles (B) Raschig rings (C) Pall rings (D) Intalox saddles
Last Answer : Berl saddles
Description : Diameter to height ratio for a raschig ring is (A) 1 (B) 0.5 (C) 2 (D) 8
Last Answer : (A) 1
Description : The sphericity of a cylinder of 1 mm diameter and length 3 mm is (A) 0.9 (B) 0.78 (C) 0.6 (D) 0.5
Last Answer : (A) 0.9
Description : Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is (A) 0.5 (B) 1 (C) √2 (D) √3
Last Answer : (B) 1
Description : Raschig ring made of porcelain cannot be used for treating concentrated (A) Hydrochloric acid (B) Nitric acid (C) Alkalis (D) Sulphuric acid
Last Answer : (C) Alkalis
Description : For a non-spherical particle, the sphericity (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle (B) Has ... of volume of a sphere having the same surface area as the particle to the actual volume of the particle
Last Answer : (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle
Description : If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by (A) φs = 6 Vp /dpsp (B) φs = Vp /dpsp (C) φs = 6 dpSp /Vp (D) φs = dpSp /Vp
Last Answer : (A) φs = 6 Vp /dpsp
Description : The sphericity of a solid particle of cubical shape is (A) π (B) (π/6) 1/3 (C) (π/6) 1/2 (D) π/3
Last Answer : (B) (π/6) 1/3 (C) (π/6) 1/2
Description : Sphericity of pulverised coal is (A) 1 (B) < 1 (C) > 1 (D) ∞
Last Answer : (B) < 1
Description : Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle). (A) 6.V/D.S (B) V/6D.S (C) D.S/V (D) V/D.S
Last Answer : (B) V/6D.S (C) D.S/V (D) V/D.S
Description : Reciprocal of sphericity is termed as the (A) Specific surface ratio (B) Shape factor (C) Sauter diameter (D) Surface area per unit mass
Last Answer : (B) Shape factor
Description : Which of the following statements is true concerning all three-phase alternators? A. Each has three separate but identical armature windings acted on by one system of rotating magnets. B. Each has one ... The three phases always provide power to the load through three sets of slip rings and brushes.
Last Answer : Answer: A
Description : __________ rubber is generally used for making 'O' rings used for vacuum sealings. (A) Natural (B) Neoprene (C) Butadiene (D) Nitrile
Last Answer : (B) Neoprene