SHIPBOARD DAMAGE CONTROL, PERSONNEL PROTECTION, FIREFIGHTING AND CBR-D
 MUSEUM WEBSITE
 
DAMAGE CONTROL MUSEUM
DC EQUIPMENT Museum
 
Breathing Apparatus  
 
Hose Air-Line Mask Assembly
 
There were many situations onboard ship that were not considered an emergency but required breathing protection (e.g., spray painting, entering a void or tank, work on or around the CHT system). In a non-casualty situation, the damage control assistant, gas free engineer or his designated assistant had to carefully evaluate all potential exposure to fumes, gases or toxic hazards. The hose air-line mask was developed in the 1940s for such situations. It could also be used for diving in a tank or over the side under controlled conditions (36-foot depth or less). It was not used in firefighting. The first hose air-line mask assemblies were developed in 1943. They were fabricated using modified ND Mark III and ND Mark IV gas mask face pieces. They had a dual air hose connected to an air intake “T” attachment, supplied by a 5/16-inch inside diameter by 50-foot rubber air hose that connected to a compressed air bottle fitting. The compressor air bottle contained 200 cubic feet of air. Fully charged, it lasted the wearer 1 ½ to 2 ½ hours. A portable air hand pump with an intervening air reservoir also was used. If a hose was used to run out to fresh air, it could be no longer than 25 feet with an inside diameter of 1 inch. The assembly had a cotton harness, a safety belt and a 50-foot by 5/16-inch steel tending line with snap latch hooks that attached to the “D” ring on the center of the harness assembly. In 1951, development of the new hose air-line mask was one of many measures undertaken for personnel protection while Sailors were performing various tasks onboard U.S. Navy ships. It was developed to be used as a protective device worn by personnel entering unsuitable atmospheres during routine work or rescue, and later for shallow water (to 36 feet) diving operations. By 1959, the U.S. Navy authorized the use of a new hose air-line mask for shipboard equipment and inclusion in the hull and repair locker allowance. This new assembly had a redesigned, monocular face piece and intervening pressure regulator. Onboard ships, low-pressure air systems had air-line manifolds installed for two or four hose air-line mask connections; two stage regulators and air filters were also installed, to reduce the pressure and remove impurities from the air. One man could breathe sufficiently through up to 250 feet of air hose. Long runs of air hose had to be watched closely by tending personnel to ensure that the line did not foul and that the hose was kept off of hot decks. The new hose air-line mask had a belt-mounted constant flow respirator with a speaking diaphragm, full vision plastic lens with adjustable head harness, breathing tube, and a special body harness with a “D” ring on back to attach the safety line. The constant flow regulator created a slight positive pressure inside the mask. This positive pressure ensured that no harmful air could leak in and provided breathing air and eye protection in spaces contaminated by any type of gas or vapor, and in a space where there was a lack of oxygen.
Image of Hose Air-Line Mask Assembly

For more information, see the Index.