- Ensure bypass v/v is fully closed.
- Open cylinder valve to check if cylinders are fully charged, whistle will be heard as the pressure rises.
- Close cylinder valve. Provided it does not fall to zero in less than 30 sec then the set is leak tight
- Demist mask visor with anti dim solution.
- Don apparatus put on mask and open cylinder valves.
- Inhale deeply twice or thrice to ensure that air is flowing freely from the demand v/v and the exhalation valve is functioning correctly.
- Close cylinder v/v and inhale until air in the mask is exhausted. Now inhale deeply, the mask must collapse on the face indicating an airtight fitness of both mask exhalation v/v.
- Reopen cylinder v/v.