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