MEOclassIIexamnotes

  When two pumping units are fitted and only one is running, the idle pump might be driven in the reverse direction by fluid under pressure from the running pump, if non-reverse locking gear were not fitted. This gear is integral with the flexible coupling connecting motor and pump.  It consists of a number of steel pawls so mounted on the motor coupling that, when pumping units are running, they fly outward due to the centrifugal effect and remain clear of the stationary steel ratchet secured to the motor supporting structure.  The limit of this outward movement is reached when the pawls contact the surrounding casing, which revolves with the coupling. When the pumps stop, the pawls return to their normal, inward position and engage the ratchet teeth, so providing a positive lock against reverse rotation.  This action is automatic and permits instant selection and commissioning of either unit without needing to use the pump isolating valves, which are normally open ...

Neutral Neutral is return path for an AC circuit which is supposed to carry current in normal condition. This current may be because of many reasons, primarily because of phase current imbalance and some time because 3rd and 5th harmonics also.  There may be others reasons too but the magnitude of this current is in fraction of phase current and in few case it can be even double of phase current. So Neutral wire is always assumed to be charged (in active circuit). This neutral wire is given to ground (by grounding) to make the second terminal of neutral wire at zero potential. Earth or Ground Earth or Ground is for safety concerns against leakage or residual currents on the system via least resistance path. While phase and neutral is connected to main power wiring, earth may be connected to body of equipment or to any system which in normal condition doesn’t carry current but in case of some insulation failure, is supposed to carry some minor current. This current is not direc...

Air conditioners are designed on the basis of quantity of heat removal from room, hall or specific area.  Quantity of heat is termed in Tons means if an air conditioner is able to remove 1000 kilocalories of heat or 4120 kilojoules or 12000 BTU of heat in an hour that AC rated as 1 Ton of AC because 1000 Kilocalories or 4120 kilojoules or 12000 BTU ( BTU = British thermal unit. A measurement of heat, specifically, the amount of heat needed to raise the temperature of a pound of water by 1°F ) equal to one Ton of heat.  Also, this is the same case for freezer and refrigerator i.e. refrigeration system.    Ton of Refrigeration : A Ton of refrigeration  is a unit of power used to describe the heat extraction capacity of air conditioning and refrigeration equipments.  It is defined as the heat of fusion absorbed by melting 1 short ton of pure ice at 0 °C (32 °F) in 24 hours.

To make use of propeller outflow for thrust. The increased velocity of the propeller outflow results in a greater lift force. If a rudder is placed just forward of the propeller, it will have the same turning effect with respect to direction, but the magnitude won’t be the same. The pivoting point of ship is 1/6 to 1/3 rd of length of ship from bow, the greater the perpendicular distance between point of action of force and pivoting point, the better rudder movement. Better protected at astern from damage. Drag is reduced if rudder is situated aft

There is no way to determine this.The complete system is designed in such way that all including syphon tubes, flexible hose dia, main maniflold dia, no of nozzles, nozzles dia etc etc and all such design based parameters would ensure that atleast 85 percent Co2 is relased within 2 mins.

  If one would look carefully, it is noticed that the two springs have their coil in opposite direction.One is right handed and other left handed. This is important since when the springs compress and decompress at high speed , there is a side thrust acting on the spring retainer due to coils of spring. To cancel this side thrust, another spring with opposite coil direction is introduced. Since the side thrust from second spring is opposite to that of first spring, the net side thrust is zero.  There is the effect of resonance at high engine speed. To prevent the matching of natural frequency of the running engine to the natural frequency of the spring, additional spring is added. This addition increases the natural frequency of the spring combination much higher than the engine's natural frequency, thus preventing any damage to the engine by excessive amplitude of vibration.  Tw o spring do provides an additional safety in case of failure of one. But r...

Circular hoops can withstand internal pressure by pure tension in the tankmaterial instead of bending. Materials can take more force in tension than inbending.  If the shape were not circular, then there would be bending stresses in the tank wall and it would not be able to withstand as much pressure without breaking.  Spheres are more efficient than cylinders if you just care about minimizing the mass of the tank to hold a certain amount of pressurized gas. But cylinders are easier to pack together. So it’s a trade-off between efficiency and practicality.