Plenum type air distribution system for head enclosure

#This invention relates to plenum type air distribution systems for head enclosures of the type worn during sandblasting operations, for example, and more particularly to a combination air diffusing and noise attenuating means for use in such systems.

#Health and safety requirements dictate that those working in atmospheres contaminated with airborne substances wear a head enclosing hood the interior of which is supplied with pure respiration air. The respiration air is typically supplied under pressure to the interior volume of the hood through a tube having one or more openings within the hood. However, when a large volume of air under pressure passes through an opening, it will produce a whistle-like sound at an audible level that is particularly bothersome and fatiguing within a head enclosure or hood. Sounds tend to reverberate within an enclosure particularly where the enclosure is rigid and does not include means for damping or attenuating such sounds. Where the enclosure is a head enclosure, a very high noise level within the enclosure is easily achieved by a constant source of sound within the head enclosure.

#It is an object of this invention to provide an improved plenum type air distribution system for use within a head enclosure which includes an air diffusion means that not only makes a reduced contribution to the sound present within the head enclosure, but also tends to attenuate sound within the enclosure.

#The foregoing and other objects and features of advantage of this invention will be more clearly understood from a reading of the following specification with reference to the accompanying drawing wherein:

#FIG. 1 is a perspective view of a head enclosing helmet to which this invention may be applied with advantage.

#FIG. 2 is a side view in elevation of a head enclosing hood to which the teaching of this invention may be applied with advantage.

#Referring to FIG. 1, a head enclosure in the form of a helmet 10 to which this invention may be applied with advantage, is shown in perspective. The helmet 10 is made of a rigid material such as heavy gauge plastic having appropriate structural strength and hardness, for example, and includes a head protective portion 12 and a face mask portion 14 designed to fully enclose the head and face of the wearer. A transparent or translucent protective lens 16 is provided in the face mask portion 14 of the helmet 10 opposite the face of the wearer for optical purposes and to protect the eyes of the wearer.

#In order to provide respiration air for the wearer of the helmet 10, a plenum type air distribution means is provided within the interior of the helmet 10 and a fitting 18 in communication therewith is provided on the exterior of the helmet 10. Thus, an air supply tube or hose, as indicated in dotted lines in FIG. 1, may be connected to the fitting 18 to provide a positive pressure of pure respiration air within the helmet 10. Such a plenum type air distribution system within the helmet 10 will not only insure that the wearer will have a constant supply of fresh air but will also prevent the entry into the helmet of air contaminated by airborne substances from the surrounding atmosphere as when the helmet 10 is worn during sandblasting operations, for example.

#Referring to FIG. 2, the teaching of this invention is also applicable to head enclosures in the form of a flexible hood 20. As shown in FIG. 2, the flexible hood 20 is designed to completely enclose the head and neck of the wearer and is provided with an appropriate protective lens 26 in the wall thereof adapted to be disposed in front of the face of the wearer.