SWOV is an automatic switching device of the air feeding source, from air network to back-up breathing apparatus (Sekur Navy Mask) which intervenes in case the air line should stop or its pressure significantly drop.
SWOV consists of a stamped and nickel-plated brass body, carried in the belt, which is normally fed, through rapid connection, by the air line and in its turn feeds, through a M pressure hose, a demand valve and a mask. On SWOV body there is also a second input connection from an alternative emergency source or escape (SNM).
The device activates automatically if you stop feeding from the airline, or if its pressure is lowered to such a low value to make difficult to breathe. Its activation is announced by an acoustic signal with a sound over 90 dB.
If the feeding conditions from the net are restored to their normal values, the SWOV automatically excludes the second source and returns in a stand-by position (warning signal is switched off).
As a further security, SWOV is the only valve with an additional manual button which can be pressed any time. This operation will manually switch to the secondary source only if the conditions allow for the SWOV to work. Otherwise it will not have any effect.
Point 5.8 UNI EN 14593-1 - Respiratory protective devices - Compressed air line breathing apparatus with demand valve Part 1: Apparatus with a full face mask - Requirements, testing, marking.