The Dräger Tramix firefighter nitrox SCR
In 1992, Dräger developed a replacement for the Travox and BG-174, which were to be discontinued. The new Tramix, replacing the Travox, offers an extended protection time of at least two hours, theoretically up to four hours for light work. The device is equipped with a 3-liter cylinder with a pressure of 300 bar, filled with a mixture of 40% oxygen and 60% nitrogen. This increases the constant dosage to 3.3 liters per minute, keeping the device almost always under pressure. An additional measure is the spring-loaded breathing bag, which helps maintain the pressure regime and prevents ambient air from entering the breathing circuit in case of a leak. The device also features a lung automaton, bypass, and automatic flushing. All functions are monitored by electronics. The warning signal checks both the operation of the reducing valve and the remaining pressure in the cylinder, signaling first at 50 bar and then at 10 bar.
The dimensions of the Tramix are 595 x 450 x 145 mm, which is significantly larger than the Travox and may pose problems in confined spaces. The weight without the air cooler is 12 kg and with the filled cooler 13.2 kg, which is 3 kg more than the Travox. The breathing hose outlet is mounted on the shoulder.
The second device, the BG-4 EP, replaces the BG-174. This device is equipped with a 2-liter cylinder with a pressure of 200 bar, filled with medical oxygen. The dosage is classic, with a constant dose of 1.5 liters per minute, a lung automaton, bypass, and automatic flushing. As with the Tramix, the breathing bag is equipped with springs to ensure overpressure in the breathing circuit. The absorber is filled with soda lime, and there is an air cooler filled with ice in the breathing circuit. This device is also monitored by the electronic Monitron system, similar to the Tramix. The dimensions are again 595 x 450 x 145 mm, and the weight without the cooler is 12.8 kg and with the filled cooler 14 kg. The breathing hose outlet is also mounted on the shoulder.
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