(2) Operation of single-stage oxygen regulator.
(a) The oxygen enters the regulator through the high-pressure inlet
connection and passes through a glass wool filter which removes dust and dirt. The
seat which closes off the nozzle is not raised until the adjusting screw is turned
in. Turning in the adjusting screw applies pressure to the adjusting spring which
bears down on the rubber diaphragm. The diaphragm presses downward on the stirrup
and overcomes the pressure on the compensating spring. When the stirrup is forced
downward, the passage through the nozzle is opened and oxygen is allowed to flow
into the low-pressure chamber of the regulator. From here the oxygen passes
through the regulator-outlet and the hose to the torch. A certain set pressure
must be maintained in the low-pressure chamber of the regulator so that oxygen will
continue to be forced through the orifices of the torch, even if the torch needle
valve is open. This pressure is indicated on the working pressure gage of the
regulator and depends on the position of the regulator adjusting screw. The
pressure is increased by turning the adjusting screw to the right and decreased by
turning to the left.
(b) Regulators used at stations to which gases are piped from an oxygen
manifold, acetylene manifold, or acetylene generator have only one low-pressure
gage because the pipe line pressures are usually set at 15 PSI for acetylene and
approximately 200 PSI for oxygen.
(3) Two-stage oxygen regulator. The operation of the two-stage regulator is
similar in principle to that of the single-stage regulator. The difference is
that the total pressure decrease takes place in two steps instead of one, On the
high-pressure side the pressure is reduced from cylinder pressure to intermediate
pressure. On the low-pressure side the pressure is reduced from intermediate
pressure to working pressure. Because of the two-stage pressure control, the
working pressure is held constant and pressure adjustments during welding
operations are not required.
(4) Acetylene regulator. This regulator controls and reduces the acetylene
pressure from any standard commercial cylinder containing pressures up to and
including 500 PSI. It is of the same general design as the oxygen regulator but
will not withstand such high pressures. The high-pressure gage, on the inlet side
of the regulator, is graduated from 0 to 500 PSI. The low-pressure gage, on the
outlet side of the regulator, is graduated from 0 to 30 PSI. Acetylene should not
be used at pressures exceeding 15 PSI.
d. Hose.
(1) The hose used to make the connection between the regulators and torch
is made especially for this purpose. It is built to withstand high internal
pressures. It is strong, nonporous, light, and flexible to permit ready
manipulation of the torch. The rubber used in its manufacture is chemically
treated to remove free sulfur so as to avoid possible spontaneous combustion. The
hose is not impaired by prolonged exposure to light.
(2) The oxygen hose is green and the acetylene hose is red. The hose is a
rubber tube with braided or wrapped cotton or rayon reinforcements and a rubber
covering. For heavy-duty welding and cutting operations, requiring 1/4- to 1/2-
inch internal diameter hose, three to five plies of braided or wrapped
reinforcements are used. One ply is used in the 1/8- to 3/16-inch hose for light
torches.
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