10. Which has more Efficiency Diesel Engine or Petrol Engine? Ans. Diesel engine has the better efficiency out of two. 1. What is Difference between stamina and strength? Ans. Strength is capability over a short length of time and Stamina is the ability to keep going continuously. 2. What is Hydrostatic System? Ans. Hydrostatics is the study of fluid bodies that are • At rest • Moving sufficiently slowly so there is no relative motion between adjacent parts of the body For hydrostatic situations • There are no shear stresses • There are only pressure forces that act perpendicular to any surface. It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply. 3. What is Cotter joint? Ans. A cotter joint is used to connect rigidly two co-axial rods or bars which are subjected to axial tensile or compressive forces. Here shaft is locked in place by a smaller pin that passes through the side of the lug and partly or completely through the shaft itself. This locking pin is named as cotter. 4. How is the excess discharge pressure prevented? Ans. Discharge pressure prevented by a pressurized spike cushion. Here the system employs a pressurized cushion of air and a two o-ring piston, which permanently separates this air cushion from the water system. When the valve closes and the water flow is suddenly stopped, the pressure spike pushes the piston up the arrester chamber against the pressurized cushion of air. The air cushion in the arrester reacts instantly, absorbing the pressure spike that causes water hammer. 5. What is the difference between Strainer and Fitler? Ans. Strainer for coarse size, Filter is more accurate than Strainer. 6. What is the position of Piston Ring? Ans. In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck. 7. Why Deareator are placed at Hieght, In Thermal Power Plant? Ans. To build a Very high pressure and the temperature for a boiler feed water pump and it discharge high pressure water to the boiler. And to provide the required Net Positive Suction Head (NPSH) for the BFW pump and to serve as a storage tank to ensure a continuous supply of feed water during rapid changes in BFP. 8. What is meanst by One Tonn Air-Conditioner? Ans. 1 ton refrigeration means 210 kJ/min extracts heat from thesystem. 9. State 1st Law of Thermodynamics? Ans. HEAT AND MECHANICAL WORK ARE MUTUALLY CONVERTABLE. ENERGY CAN BE CREATED NOR BE DISTROYED BUT IT CAN BETRANSFERED FROM ONE FORM TO ANOTHER FORM. 10. If you heat a steel pipe with the hole at center, does heat affects the hole diameter? Ans. It gets bigger. 1. Why the Centrifugal Pump is called High Discharge pump? Ans. Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following formulae: Centrifugal force F= (M*V2)/R. Where, M-Mass V-Velocity R-Radius 2. How Cavitation can be eliminated by Pump? Ans. Cavitation means bubbles are forming in the liquid. • To avoid Cavitation, we have to increase the Pump size to One or Two Inch; To increase the pressure of the Suction Head, or • Decrease the Pump Speed. 3. Why Cavitation will occur in Centrifugal Pump and not in Displacement Pump? Ans. The formation of cavities (or bubbles) is induced by flow separation, or non-uniform flow velocities, inside a pump casing. In centrifugal pumps the eye of the pump impeller is smaller than the flow area of pipe. This decrease in flow area of pump results in increase in flow rate. So pressure drop happened between pump suction and the vanes of the impeller. Here air bubbles or cavities are formed because of liquid vapour due to increase in temperature in impeller. This air bubbles are transmitted to pump which forms cavitation. 4. Which Pump is more Efficient Centrifugal Pump or Reciprocating Pump? Ans. Centrifugal pump. Because flow rate is higher compared to reciprocating pump. Flow is smooth and it requires less space to install. Lower initial cost and lower maintenance cost. 5. Why Centrifugal Pump is not called as a Positive Displacement Type of Pump? Ans. The centrifugal has varying flow depending on pressure or head, whereas the Positive Displacement pump has more or less constant flow regardless of pressure. Likewise viscosity is constant for positive displacement pump where centrifugal pump have up and down value because the higher viscosity liquids fill the clearances of the pump causing a higher volumetric efficiency. When there is a viscosity change in supply there is also greater loss in the system. This means change in pump flow affected by the pressure change. One more example is, positive displacement pump has more or less constant efficiency, where centrifugal pump has varying efficiency rate. 1. Why Entropy decreases with increase in temperature? Ans. ds=dQ/T Entropy is inversely proportional to the temperature so, as temp. Increases, entropy decreases. 2. Why different types of sound are produced in different bikes, though they run on SI Engines? Ans. Engine specifications are different in different manufactures like as Bore Diameter (CC), Ignition timing. Also the exhaust passage takes more responsible for sound. 3. How much Watt means 1Hp? Ans. 746.2 Watt
Posted on: Thu, 22 Jan 2015 11:05:51 +0000
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