Balanced vs. unbalanced 2nd stage

[pescador775]

Kiko, you can probably find some other sources for that information. Balancing is just a word to describe a poppet valve or piston whose design is such that the variations in source pressure don't impose variable forces on the back of the poppet or piston stem. In respect to the first stage this feature prevents variations in the regulator intermediate pressure; for example, when faced with dropping source pressure may: 1) rise with an unbalanced diaphragm reg and 2) drop with an unbalanced piston. A "balanced" second stage appears superficially similar to a balance diaphragm reg but is not really intended as a balancing mechanism although it could potentially act like one in some circumstances. Really, the second is a pneumatic spring which uses air pressure to take over some of the duties of the mechanical spring allowing use of a lighter steel spring and reducing indentation of the poppet seat during storage. It has little practical effect on breathing effort or rhythm.