REGULATORS AND VALVES

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REGULATORS AND VALVES

While the pressure in the gas containers may be
anything from zero to 1,800 pounds, and will vary as the gas is
withdrawn, the pressure of the gas admitted to the torch must be held
steady and at a definite point. This is accomplished by various forms of
automatic regulating valves, which, while they differ somewhat in
details
of construction, all operate on the same principle.

The regulator body (Figure 14) carries a union which attaches to the
side
outlet on the oxygen tank valve. The gas passes through this union,
following an opening which leads to a large gauge which registers the
pressure on the oxygen remaining in the tank and also to a very small
opening in the end of a tube. The gas passes through this opening and
into the interior of the regulator body.

Inside of the body is a metal or rubber diaphragm placed so that the
pressure of the incoming gas causes it to bulge slightly.
Attached to the diaphragm is a sleeve or an arm tipped with a small
piece of fibre, the fibre being placed so that it is directly opposite
the small hole through which the gas entered the diaphragm chamber.
The slight movement of the diaphragm draws the fibre tightly over the
small opening through which the gas is entering, with the result that
further flow is prevented.

Against the opposite side of the diaphragm is the end of a plunger.
This plunger is pressed against the diaphragm by a coiled spring.
The tension on the coiled spring is controlled by the operator through
a threaded spindle ending in a wing or milled nut on the outside of the
regulator body. Screwing in on the nut causes the tension on the spring
to increase, with a consequent increase of pressure on the side of the
diaphragm opposite to that on which the gas acts. Inasmuch as the gas
pressure acted to close the small gas opening and the spring pressure
acts in the opposite direction from the gas, it will be seen that the
spring pressure tends to keep the valve open.

When the nut is turned way out there is of course, no pressure on the
spring side of the diaphragm and the first gas coming through
automatically closes the opening through which it entered. If now the
tension on the spring be slightly increased, the valve will again open
and admit gas until the pressure of gas within the regulator is just
sufficient to overcome the spring pressure and again close the opening.

There will then be a pressure of gas within the regulator that
corresponds to the pressure placed on the spring by the operator.
An opening leads from the regulator interior to the torch lines so that
all gas going to the torches is drawn from the diaphragm chamber.

Any withdrawal of gas will, of course, lower the pressure of that
remaining inside the regulator. The spring tension, remaining at the
point determined by the operator, will overcome this lessened pressure
of
the gas, and the valve will again open and admit enough more gas to
bring
the pressure back to the starting point. This action continues as long
as
the spring tension remains at this point and as long as any gas is taken
from the regulator. Increasing the spring tension will require a greater
gas pressure to close the valve and the pressure of that in the
regulator
will be correspondingly higher.

When the regulator is not being used, the hand nut should be unscrewed
until no tension remains on the spring, thus closing the valve. After
the
oxygen tank valve is open, the regulator hand nut is slowly screwed in
until the spring tension is sufficient to give the required pressure in
the torch lines.

Another gauge is attached to the regulator so that it communicates with
the interior of the diaphragm chamber, this gauge showing the gas
pressure going to the torch. It is customary to incorporate a safety
valve in the regulator which will blow off at a dangerous pressure.

In regulating valves and tank valves, as well as all other parts with
which the oxygen comes in contact, it is not permissible to use any form
of oil or grease because of danger of ignition and explosion. The
mechanism of a regulator is too delicate to be handled in the ordinary
shop and should any trouble or leakage develop in this part of the
equipment it should be sent to a company familiar with this class of
work
for the necessary repairs.

Gas must never be admitted to a regulator until the hand nut is all the
way out, because of danger to the regulator itself and to the operator
as
well. A regulator can only be properly adjusted when the tank valve and
torch valves are fully opened.

Acetylene regulators are used in connection with tanks of compressed
gas.
They are built on exactly the same lines as the oxygen regulating valve
and operate in a similar way. One gauge only, the low pressure
indicator,
is used for acetylene regulators, although both high and low pressure
may
be used if desired. (See Figure 15.)

HAND FORGING AND WELDING

Smithing, or blacksmithing, is the process of working heated iron, steel
or other metals by forging, bending or welding them.
The Forge.--The metal is heated in a forge consisting of a shallow pan
for holding the fire, in the center of which is an opening from below
through which air is forced to make a hot fire.

Air is forced through this hole, called a "tuyere" (Figure 48) by means
of a hand bellows, a rotary fan operated with crank or lever, or with a
fan driven from an electric motor. The harder the air is driven into the
fire above the tuyere the more oxygen is furnished and the hotter the
fire becomes.

Directly below the tuyere is an opening through which the ashes that
drop
from the fire may be cleaned out.
The Fire.--The fire is made by placing a small piece of waste soaked in
oil, kerosene or gasoline, over the tuyere, lighting the waste, then
starting the fan or blower slowly. Gradually cover the waste, while it
is
burning brightly, with a layer of soft coal. The coal will catch fire
and
burn after the waste has been consumed. A piece of waste half the size
of
a person's hand is ample for this purpose.

The fuel should be "smithing coal." A lump of smithing coal breaks
easily, shows clean and even on all sides and should not break into
layers. The coal is broken into fine pieces and wet before being used on
the fire.
The fire should be kept deep enough so that there is always three or
four
inches of fire below the piece of metal to be heated and there should be
enough fire above the work so that no part of the metal being heated
comes in contact with the air. The fire should be kept as small as
possible while following these rules as to depth.

To make the fire larger, loosen the coal around the edges. To make the
fire smaller, pack wet coal around the edges in a compact mass and
loosen
the fire in the center. Add fresh coal only around the edges of the
fire.
It will turn to coke and can then be raked onto the fire. Blow only
enough air into the fire to keep it burning brightly, not so much that
the fire is blown up through the top of the coal pack. To prevent the
fire from going out between jobs, stick a piece of soft wood into it and
cover with fresh wet coal.

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Warmly,
Pat Mitchell
http://www.weldingsecrets.net/main.html