Pressure Regulators
Pressure regulators are necessary to reduce the high pressure within the compressed gas cylinder to a working pressure of around 60 psig. The pressure regulator ensures that the flow of the gas from the cylinder remains steady as the pressure in the cylinder drops. Anesthesia machines with yoke hangers for "E" cylinders have built-in regulators that are pre-set to provide this working pressure. Thus, once the "E" cylinder is attached to the yoke and opened, the pressure gauge indicates the pressure in the cylinder (Figure 26). The user should not attempt to alter this regulator.
The "G" cylinders require a gas-specific regulator. The regulator connections are threaded uniquely for each type of gas as a method for preventing inadvertent connection of an improper gas cylinder. Regulators may decrease the cylinder pressure in one or two stages. A one-stage regulator will decrease the cylinder pressure to a pre-set working pressure similar to the regulators built in the anesthesia machine (Figure 27). A two-stage regulator creates two steps in the pressure drop from the cylinder to the anesthesia machine (Figure 28). The user has the ability to adjust the working pressure with the two-stage regulator. The two-stage regulator is subject to less strenuous wear on the inner diaphragm compared to the one-stage regulator and will have a longer life span.
Figure 27.
Figure 28.