Pneumatically Balanced Second Stage

A Pneumatically Balanced Second Stage allows air to pass through the centre of the valve to a counter-balance cylinder, assisting the spring in closing the valve. This eliminates the need for a heavier spring, reducing the overall breathing effort.

Many companies claim to have a balanced regulator but all they are referring to is the first stage. The world's best performing regulators also have a balanced second stage. A traditional second stage has a valve spring strong enough to hold back all the pressure from the first stage. This spring pushes against the seating mechanism to stop the air-flow until the diver breathes. When the diver breathes the diaphragm is pulled forward against the lever, which in turn compresses the spring and pulls back the seat to allow the air to flow.

A balanced second stage allows air to pass through the center of the poppet valve to a counter-balance cylinder, which assists the spring in closing the valve. This reduces the need for a heavier valve spring, which cuts down the effort needed to compress the spring which in turn makes inhalation very easy.

A balanced second stage is therefore highly desirable.

Balancing Mechanism

• Air travels through a hole in the centre of the poppet
• Air is captured in the counterbalance chamber
• Pressure inside balance chamber aids spring to close valve; therefore a lighter spring can be used which reduces the inhalation effort.

Balanced 2nd Stage in Action

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