Life saving equipment, foldable pressure chambers for divers, pit bags for rescue of persons who have fallen in wells, lifting bags for rescue of persons, floating bags, slide and jumping sheets, emergency chutes and rescue islands; fire extinguishers; safety helmets; safety goggles; protective gas masks; liquid and dust vacuums for industrial use; potentiometers; by-pass, gate pressure, pressure reduction, interruption, relief, automatic safety check and safety valves.