Compressed air, breathing

AMD 1 Respiratory protective devices self-contained open-circuit compressed air breathing apparatus (AMD 8167J dated 15 May 1994. Supersedes BS 7004 1988 and BS 4667 Part 2 1974... 

In cases where respiratory devices are used to avoid exceeding occupational exposure limits, chemical protective suits are necessary. These are available for use against many different chemicals, and are made from various types of elastomer materials or coated fabrics. Most chemical protective suits enclose the whole body. In order to reduce any leaks, the protective boots are integrated. Normally one can choose from protective suits having fiiU face masks with a connector for a cartridge or an external compressed air breathing apparatus (Fig. 6.25 b), or with an... 

Fig. 6.26 Chemical protective suits, (a) Chemical protective suit with a self-contained open circuit compressed air breathing apparatus, (b) Chemical protective suit with a continuous flow compressed air line breathing apparatus.

In the case of this special type of self-contained respirator, the breathing air is taken from one or two canisters filled with compressed air. The technical requirements can be found in EN 137 [6-69]. The air pressure within the bottles is between 200 and 300 bar. Figure 6.42 shows the essential elements of a self-contained compressed air breathing apparatus. Because there is a small negative pressure within the mask during inhalation (only full-face masks are allowed), contaminated air could possibly get into the mask in the event of a leakage. To prevent any confusion, the connectors for such respirators are designed differently from those for over-pressure or normal pressure (see parts of EN 148 [6-84]). The air quality of compressed air botdes has to conform to EN 12021 [6-82]. 

The application area for self-contained compressed air breathing apparatus with over-pressure is only restricted by the limitation due to the air reservoir. There are no maximum concentration Hmits for these devices, so they can be used basically... 

Fig. 6.42 Self-contained compressed air breathing apparatus for bottles containing over 5 L, portable on the back with a frame.

Fig. 6.43 Self-contained compressed air breathing apparatus for hanging on the body, (a) 2-L-bottle to fix on a belt (b) 4-L-bottle to hang on the body.

EN 402 2003 Respiratory protective devices - Lung governed demand self-contained open-circuit compressed air breathing apparatus with fall face mask or mouthpiece assembly for escape — Requirements, testing, marking. 

CFR1910.120(q)(3)(x) 4.3.10 When deemed necessary by the safety officer for meeting the tasks at hand, approved self-contained compressed air breathing apparatus may be used with approved cylinders from other approved self-contained compressed air breathing apparatus provided that such cylinders are of the same capacity and pressure rating. All compressed air cylinders used with self-contained breathing apparatus shall meet U.S. Department of Transportation (USDOT) and National Institute for Occupational Safety and Health (NIOSH) criteria. 

F omunassenaufbereitung compress stauchen (condense/compact/ concentrate/thicken) verdichten compressed/contracted gestaucht, zusammengezogen compressed air/ pressurized air Druckluft, Pressluft compressed air breathing apparatus Pressluftatmer compressed gas/ pressurized gas Druckgas compressibiiity Komprimierbarkeit,... 

Type 1 CPC, vapor-protective suits are divided into subtypes. Type la has a breathable air supply inside the chemical protective suit. The air supply can be, for example, self-contained open-circuit compressed air breathing apparatus. In type lb, the breathable air supply is worn outside the CPC. To type Ic positive pressure of breathable air is provided via air hose [standard EN 943-1]. Types la-ET and Ib-ET are meant for emergency teams [EN 943-2]. Type 1 CPC is meant against hazardous gases, liquids, aerosols, and solid particles. The chemicals may be very hazardous such as dimethyl sulphate, ammonia, chlorine, cyanogen chloride, hydrogen cyanide, sulphur mustard, and Sarin. 

The isolation of certain mechanical equipment, e.g. conveyors, work on lifts, excavations, entry and positioning of cranes, isolation of various safety services , e.g. water or inert gas, stand-by power generation, water supply to sprinkler systems, compressed air for breathing apparatus. 

Breathing apparatus Light duty construction air line Fresh air hose and compressed air line Self contained 10-2000... 

AMD 2 Respiratory protective devices - Compressed air line breathing apparatus for use with a full face mask, half mask or a mouthpiece assembly - Requirements, testing, marking (AMD 10774J dated Januai-y 2000. With BS EN 138, BS EN 269 and BS EN 270, superseded BS 4667-3 1974... 

An operator donned a fresh-air hood to avoid breathing harmful fumes. Almost at once he felt ill and fell down. Instinctively he pulled off the hood and quickly recovered. It was then found that the hood had been connected by mistake to a supply of nitrogen instead of compressed air. 

The compressor intake air must be clean and free from solid and gaseous impurities abrasive dust and corrosive gases are particularly harmful. Exhaust fumes present a hazard if compressed air is required for breathing purposes. The possibility of contamination of the intake by discharge from pressure-relief devices of other plant must be taken into consideration and changes of wind direction must not be overlooked. 

Another consequence of the effect of pressure on gas solubility is the painful, sometimes fatal, affliction known as the bends. This occurs when a person goes rapidly from deep water (high pressure) to the surface (lower pressure), where gases are less soluble. The rapid decompression causes air, dissolved in blood and other body fluids, to bubble out of solution. These bubbles impair blood circulation and affect nerve impulses. To minimize these effects, deep-sea divers and aquanauts breathe a helium-oxygen mixture rather than compressed air (nitrogen-oxygen). Helium is only about one-third as soluble as nitrogen, and hence much less gas comes out of solution on decompression. 

Proper training and instruction for anyone required to use air-fed breathing apparatus. Restriction of exposures to compressed air to safe levels. 

Air line respirators are similar to hose respirators, except that they are supplied with compressed air from a clean air source and compressor. They provide complete protection, and because they offer little in the way of breathing resistance, they are more suitable than hose respirators for prolonged use. There are two basic types continuous flow and demand flow. 

Another area in which the gas laws play a key role is in scuba diving. At the surface, we breath air at a pressure of approximately 1 atmosphere. The partial pressures of nitrogen and oxygen are 0.78 and 0.20 atmosphere, respectively. A scuba diver breaths compressed air that is delivered at a pressure that corresponds to the pressure at the depth of the diver. Because 33 feet of... 

Another example of a diving problem that is a direct consequence of Dalton s Law of partial pressure concerns oxygen toxicity. The deeper a diver descends, the greater the partial pressure of oxygen. At a depth of 130 feet, the total pressure is close to 5 atmospheres and the partial pressure of oxygen will be close to 1 atmosphere (21% X 5 atmospheres). What this means is that breathing compressed air at 130 feet is like... 

Now that we have determined what processes the facility will be used for, we can finalize utility requirements. The following utilities are required for our solid-dose facility heating, ventilation, and air conditioning (HVAC), hot and cold water, steam, electrical service, compressed air, vacuum systems, dust collection, chillers, effluent stream, and purified water. For the more specialized processes or special material handling, we may need specialized gases and breathing air. Purified water is one of the more difficult utilities to maintain the quality of. From a source of potable water, a series of treatments must be performed to control microbiological quality. Typical treatment options include carbon filters, reverse osmosis, and UV radiation. 

A scuba diver swimming underwater breathes compressed air at a pressure of 2 atmospheres. If she holds heT breath while returning to the surface, by how much does the volume other lungs tend to increase ... 

Deep-sea divers breathe compressed air. Nitrogen is not very soluble in blood at normal pressures but at great depths, when the divers bodies are exposed to very high pressures, the nitrogen becomes more soluble. The dissolved nitrogen comes out of solution rapidly when the divers return to the surface, and numerous small bubbles form in the bloodstream. These bubbles can burst the capillaries—the narrow vessels that distribute the blood—or block them and starve the tissues of oxygen... 

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