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66
Regulators
You must be able to reduce the high-pressure gas in a cylinder to a
working pressure before you can use it. This pressure reduction is done by a
regulator or reducing valve. The one basic job of all regulators is to take the
high-pressure gas from the cylinder and reduce it to a level that can be safely
used. Not only do they control the pressure but they also control the flow
(volume of gas per hour).
Regulators come in all sizes and types. Some are designed for high-
pressure oxygen cylinders (2,200 psig), while others are designed for low-
pressure gases, such as natural gas (5 psig). Some gases like nitrous oxide or
carbon dioxide freeze when their pressure is reduced so they require
electrically heated regulators.
Most regulators have two gauges: one indicates the cylinder pressure
when the valve is opened and the other indicates the pressure of the gas
coming out of the regulator. You must open the regulator before you get a
reading on the second gauge. This is the delivery pressure of the gas, and you
must set the pressure that you need for your particular job.
The pressures that you read on regulator gauges is called gauge
pressure. If you are using pounds per square inch, it should be written as psig
(this acronym means pounds per square inch gauge). When the gauge on a
cylinder reads zero, this does not mean that the cylinder is empty. In
actuality, the cylinder is still full of gas, but the pressure is equal to the
surrounding atmospheric pressure. Remember: no gas cylinder is empty
unless it has been pumped out by a vacuum pump.
Problems And Safety
Regulators are precise and complicated pieces of equipment.
Carelessness can do more to ruin a regulator than any other gas-using
equipment. One can easily damage a regulator by simply forgetting to wipe
clean the cylinder, regulator, or hose connections. When you open a high-
pressure cylinder, the gas can rush into the regulator at the speed of sound. If
there is any dirt present in the connections, it will be blasted into the
precision-fitted valve seats, causing them to leak. This results in a condition
that is known as creep. Creep occurs when you shut of the regulator but not
the cylinder and gas pressure is still being delivered to the low-pressure side.
Regulators are built with a minimum of two relief devices that protect
you and the equipment in the case of regulator creep or high-pressure gas
being released into the regulator all at once. All regulator gauges have
blowout backs that release the pressure from the back of the gauge before the
gauge glass explodes. Nowadays, most manufacturers use shatterproof plastic
instead of glass. The regulator body is also protected by safety devices.
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