Function of the reserve
The pressure in the cylinder is abouve 40-80bar (tolerance of the reserve circuit) position of the shift lever shows this position. Normal breathing for the diver. Position of the shift lever see picture below. Activating accidentally above the opening value (50-80bar) is not possible. Reserve automatically jumps into the unactivated state.
The diver reaches the reserve area (40-80 bar) closes the reserve and the respiratory resistance increases noticeably. Continue breathing is possible but with increased resistance. Respiratory resistance is back to normal!
If the cylinders are refundled above (40-80bar), the reserve will automatically return to the inactivated state again.