Two-hose machine
Two-hose automats represent the design of the first regulators developed around 1942 , which make it possible to breathe from a compressed air cylinder while diving and so stay under water for a longer period of time. In contrast to current regulators, the first two-hose machines only had a single-stage pressure reduction , i.e. H. the cylinder pressure was adjusted directly to the ambient pressure.
Principle and history
The cylinder pressure in a compressed air cylinder was regulated down to ambient pressure by a pressure reduction system. This air at ambient pressure was then fed from the machine through two soft, non-pressure-resistant rubber bellows hoses to a mouthpiece. The air flow in these two hoses was controlled by one-way valves so that the inhaled air was fed through one hose and the exhaled air was discharged through the other hose to the rear of the regulator. There it could be blown into the surrounding water. Since two uniform bellows hoses led from the mouthpiece to the machine with this type, this type was called "two-hose machine". These voluminous two bellows hoses have long defined the typical image of a diver.
The direct reduction of the cylinder pressure to ambient pressure used in the first machines led to a high valve control force . Therefore, the diver had to create a slight negative pressure when breathing in , which led to a high breathing resistance and thus moderate breathing comfort. Soon afterwards, a two-stage principle was introduced, which enabled the valve to be set much more precisely. Breathing comfort increased as a result, as simple inhalation was sufficient to open the valve. In the two-stage systems, the mean pressure was typically around eight bar above ambient pressure. Based on the construction principle of the one-stage machine, the first two-stage machines were also arranged in a housing directly on the cylinder valve.
This principle of two hoses had the advantage that the mouthpiece was very light and no annoying bubbles rose in front of the diver's mask. This was particularly popular with underwater photographers and filmmakers. The main disadvantage was that the second stage could only regulate down to the ambient pressure at which the machine was located, and not to the ambient pressure of the mouthpiece. As a result, the air pressure at the mouthpiece was significantly higher when the regulator was a little lower and, conversely, a clearly noticeable negative pressure when the regulator was higher. When diving, this had the effect that the diver was exposed to overpressure from the regulator on the ascent, while he had to suck heavily when descending. This construction principle has therefore not caught on.
Since 2005, two-hose machines with modern two-stage technology and the advantages of both systems have been launched, which now also meet the European standard EN-250.
literature
- Michael Jung: The manual for diving history. Delius Klasing, June 1999, ISBN 3-925342-35-4 .
Individual evidence
- ↑ Ilka Weber, Michael Goldschmid: Test Aqualung Mistral. ( Memento of the original from October 9, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Unterwasserwelt.de.
