Respiratory protective helmet with visor - has flowmeter inside helmet near outlet end of induced air supply tube

摘要

The respiratory helmet contains an electric ventilator with a fan and a filter in the respiratory air flow. A warning signal is delivered if the minimum supply output of the fan is not attained. Inside the helmet (1) is mounted a flowmeter (4) near the outlet end (3) of the air supply tube (2) from the fan. Pref. the flowmeter is in the form of an L-shaped tube which acts as a pilot tube. Its vertical shank contains a ball of light material, the outside of the shank having a volume scale. Between the scale divisions are coloured surfaces. The bore of the horizontal shank is directed against the respiration air flow. The bores of the shanks are covered by screens. Alternately the flowmeter may consist of a ball suspended on a thread. Sections of the deviation surfaces of this suspension against the wall of the air supply tube serve as an indication of the supply volume.