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In a message dated 11/13/98 10:22:34 AM Eastern Standard Time, kevin@nw*.co* writes: >what did >you mean by not using an "air balanced second stage" for the backup reg? > Also, when you said "slow to blow" seats, does that mean a reg that gets a > HP creep when the seats go bad instead of free flowing? A G250/Apex type 2nd is an "air" or pneumatically balanced 2nd stage that actually uses a small "upstream" force to assist in the opening of the poppet (via a small hole down the center of the poppet to a "balance chamber" behind the poppet spring). They "crack" or start to flow easier then an "unbalanced" 2nd stage becuase of the upstream force and can start a free flow easier then an unbalanced 2nd stage... HP creep is a function of the 1st stage HP seat taking a cut (scribing) allowing HP tank air past the piston, overcoming the 2nd stage poppets set spring pressure (most 2nd stages will free flow at about 170 psi as a safety factor to avoid LP hose rupture). My guess would be that he is referencing a solid disk poppet like a R190 that is opened purely by downstream and inhalation (mechanical) force against the poppet spring. Sean Cary -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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