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WELDER - CITS



           When the spindle of the cylinder is opened slowly, the high pressure gas from the cylinder enters into the regulator
           through the gas then enters the body of the regulator which is controlled by the needle valve. The pressure
           inside the regulator rises which pushes the diaphragm and the valve to which it is attached, closes the valve and
           prevents any more gas from entering the regulator. The outlet side is fitted with a pressure gauge which indicates
           the working pressure on the blowpipe. Upon the gas being drawn ‘off from the outlet side, the pressure inside the
           regulator body falls, the diaphragm is pushed back by the spring and the valve opens, letting more gas ‘in’ from
           the cylinder. The pressure in the body, therefore, depends on the pressure of the springs and this can be adjusted
           by means of a regulator knob.
           Welding regulator (Double stage):- Working principle:
           The  two-stage  regulator  (Fig  2)  is  nothing  but  two  regulators  in  one  which  operates  to  reduce  the  pressure
           progressively in two stages instead of one. The first stage, which is pre-set, reduces the pressure of the cylinder
           to an intermediate stage (i.e.) 5 kg/mm2 and gas at that pressure passes into the second stage, the gas now
           emerges at a pressure (Working pressure) set by the pressure adjusting control knob attached to the diaphragm.
           Two-stage regulators have two safety valves, so that if there is any excess pressure there will be no explosion. A
           major objection to the single stage regulator is the need for frequent torch adjustment, for as the cylinder pressure
           falls  the  regulator  pressure  likewise  falls  necessitating  torch  adjustment.  In  the  two  stage  regulator,  there  is
           automatic compensation for any drop in the cylinder pressure. Single stage regulators may be used with pipelines
           and cylinders. Two stage regulators are used with cylinders and manifolds.

                  Fig 1                                     Fig 2




























           Gas welding and cutting blow pipe


           Objectives : At the end of this lesson you shall be able to
           •  state the uses of the different types of blowpipes
           •  describe the working principle of each type of blowpipes
           •  explain its care and maintenance.



           Types

           There are two types of blowpipes.
           -  High pressure blowpipe or non-injector types blowpipe
           -  Low pressure blowpipe or injector type blowpipe.
           Uses of blow pipes: Each type consists of a variety of designs depending on the work for which the blowpipe is
           required, i,e., gas welding, brazing, very thin sheet welding, heating before and after welding, gas cutting.



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 CITS : C G & M - Welder - Lesson 14-26  CITS : C G & M - Welder - Lesson 14-26
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