When Carbon is dissolved in Liquid Iron, and if the solution is solidified slowly the carbon tends to separate out giving a structure which is a mixture of pure iron and graphite. This gives a fairly tough iron which breaks with a dark glistering fracture. It is easily machined. If the same iron is cast and cooled quickly, it is hard , has a higher tensile strength , is difficult to machine and breaks with a close, white fracture. The white constituent is Iron Carbide , called cementite.
CONSTRUCTION OF SIMPLE CARBURETOR : The main Components of Simple Carburetor are : Float Chamber, float, nozzle, venturi, throttle valve, inlet valve, and metering jet . In the float chamber, a constant level of petrol is maintained by the float and a needle valve. The float chamber is ventilated to atmosphere. This is used to maintain atmospheric pressure inside the chamber. The float which is normally a metallic hollow cylinder rises and closes the inlet valve as the fuel level in the float chamber increases to certain level. The mixing chamber contains venturi, nozzle and throttle valve. The venturi tube is fitted with the inlet manifold. This tube has a narrow opening called venturi. A nozzle is provided just below the centre of this venturi. The nozzle keeps the same level of petrol as that of the level in the float chamber. The mixing chamber has two butterfly valves. One is to allow air into the mixing chamber known as choke valve. The other is to al...
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