The SR 500 is a battery-powered fan that, together with a filter and an approved head top, is included in the Sundström fan-assisted respiratory protective device systems. The SR 500 can be used as an alternative to filter respirators in all situations in which these are recommended. This applies particularly to work that is hard, warm or of long duration. The human interface may consist of a hood, face shield, half mask or full face mask. The fan is equipped with a filter, and the filtered air is fed through a hose to the human interface. The pressure then generated prevents surrounding pollutants from penetrating into the mask. The characteristics of the SR 500 are as follows: The battery is of lithium-ion type • Two battery alternatives, i.e. STD (Standard 2.25 Ah) and HD (Heavy Duty 3.5 Ah) • The charging time for the Standard battery is around 1.5 hours and for the Heavy Duty battery, about 2 hours • Equipped with two filters/combined filters • Operating time of up to 13 hours • The same control is used for starting, stopping and selection of operating status • Display with symbols • Equipped with automatic air flow control with compensation for air pressure and temperature • Can be used together with hoods SR 520, SR 530, SR 561, SR 562, SR 601, SR 602 face shield SR 570, welding shield SR 570/SR 574, half mask SR 900, full face mask SR 200, welding shield SR 592, helmet with visor SR 580 or welding shield/helmet with visor SR 584/SR 580. Electronics ingress protection is approved in IP class IP67 according to IEC / EN 60529.