Title: Mechanism of diving regulators - Wikipedia
Headings: Mechanism of diving regulators
Mechanism of diving regulators
Contents
Types of diving regulators
Open-circuit scuba regulators
Connection to the high pressure supply
CGA 850 connection
DIN connection
Adapters
Conversion kits
Other connection types
Cylinder valve types
Single-hose demand regulators
First stage
Piston-type first stage
Diaphragm-type first stage
Balancing
Interstage hose
Second-stage
Upstream valves
Downstream valves
Servo-controlled valves
Exhaust valves
Exhaust manifold
Purge button
User adjustable flow modifiers
Twin-hose demand regulators
Constant mass flow regulators
Surface supply regulators
Reclaim regulators
Built-in breathing system regulators
Malfunctions and failure modes
Inlet filter blockage
Sticking valves
Free-flow
Intermediate pressure creep
Regulator freezing
Mechanism of icing
First stage freezing
Interstage gas temperature
Second stage freeze
Surface supplied breathing equipment
Factors increasing the risk of regulator freeze
Precautions to reduce risk of regulator freezing
Mitigation
Procedures for managing a regulator freeze
Gas leaks
Wet breathing
Excessive work of breathing
Juddering, shuddering and moaning
Physical damage to the housing or components
See also
References

Content: The yoke clamp fits around the valve body and the sealing face of the regulator inlet seats over the O-ring groove. A conically tipped screw locates in the indentation and when tightened, presses against the valve body and pulls the sealing face of the regulator inlet against the O-ring. This screw must be tightened sufficiently to maintain metal-to-metal contact between the regulator inlet and the valve body when the valve is opened at full cylinder pressure, and under normal working loads including minor impacts and using the regulator as a handle to lift the set, to prevent failure of the seal by O-ring extrusion and consequent loss of breathing gas. The screw must also not be over-tightened, as after use it must be removed by hand. The rigidity of the yoke varies depending on design, tightening is by hand and is left to the discretion of the user. Fortunately the mechanism is fairly tolerant of variation in contact force. When the valve is opened, gas pressure on the O-ring presses it against the outer cylindrical surface of the groove and the face of the regulator inlet, squeezing the O-ring towards the contact surfaces of these parts. The pressure exerts a force to push the regulator away from the valve body, and if pre-load of the screw is insufficient the elasticity of the clamp will allow a gap to form between valve and regulator through which the O-ring may be extruded. When this happens, gas loss is rapid, and the valve must be closed and the clamp loosened, the O-ring inspected and possibly replaced. Recovery from an extruded O-ring underwater is often not possible and bailout to an independent gas supply or an emergency ascent may be necessary.