Dual purpose air inlet method for head enclosure

Abstract

An air inlet connection for a head enclosure of the type used for sandblasting, lead grinding and the like wherein the connection includes a tubular, open end fitting having means at one end for coupling the same to the air inlet of the head enclosure. The fitting also is provided with a chamber at its opposite end for removably receiving sound-absorbing structure, whereby the air inlet connection can be releasably coupled either to a source of air under pressure and at ambient temperature or to a source of cooled air at relatively small pressure.

Parent Case Text

This is a continuation of application Ser. No. 237,310 filed Mar. 23, 1972, now abandoned.

Description

This invention relates to improvements in head enclosures of the type worn during the performance of hazardous jobs, such as sandblasting, heat grinding or the like. More specifically, the invention relates to an air inlet connection permitting such a head enclosure to be operated in either of two different operational modes.

At certain times, it is desirable to use a head enclosure of the type described in situations which require relatively high pressure air at ambient temperature to be directed into the head enclosure to protect the health and safety of the wearer. At other times, it is desirable to use the head enclosure on jobs requiring that relatively low pressure, cooled air be directed into the head enclosure. In both of these operational modes of the head enclosure, the sound level of the incoming air must be sufficiently low to avoid discomfort to the wearer and the volume rate of flow of the incoming air should be in a specific range to properly sustain respiration.

The air inlet connection of this invention allows such a head enclosure to be readily adapted for use in either of the aforesaid modes while assuring that the volume rate of flow into the head enclosure will be within a preferred range yet the noise of the incoming air will be no greater than a predetermined maximum value. Such a connection allows for a quick changeover from a source of air under pressure to a source of cooled air while meeting the aforesaid requirements. The invention is simple and rugged in construction, can be permanently attached to the air inlet of the head enclosure, and can be formed of relatively inexpensive materials.

The primary object of this invention is, therefore, to provide a method employing an improved air inlet connection for a head enclosure of the type described to allow the latter to be readily changed from operation in one mode at which relatively high pressure air at ambient temperature is directed into the head enclosure to operation in a second mode in which cooled air is directed into a head enclosure at relatively low pressure.

Another object of this invention is to provide a method employing an air inlet connection of the aforesaid character wherein the connection includes a tubular, open end fitting having a chamber at its outer end for removably receiving sound-absorbing structure with the fitting being of a size to assure that the volume rate of flow of the incoming air will be in a particular range of values to sustain respiration yet the incoming air will be silenced sufficiently to avoid discomfort to the wearer.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawing for an illustration of the invention.

In the drawing:

FIG. 1 is a side elevational view of a head enclosure utilizing the air inlet connection of the present invention;

FIG. 2 is an enlarged, fragmentary, side elevational view of the head enclosure of FIG. 1 showing the air inlet connection in a first operational mode;

FIG. 3 is an exploded view of the air inlet connection; and

FIG. 4 is a view similar to FIG. 2 but showing the air inlet connection in a second operational mode.

The air inlet connection of this invention is broadly denoted by the numeral 10 and is shown in detail in FIGS. 2 and 3. Connection 10 is adapted for use with a head enclosure 12 (FIG. 1) of the type worn by a person engaged in sandblasting, lead grinding and like tasks that produce contaminated atmospheres around the person. Such a head enclosure typically includes a rigid head or crown protecting portion 14 which flares outwardly at its lower extremity 16 and is joined with a rigid face and neck protecting portion 18. Face and neck protecting portion 18 typically includes a front transparent window 20 through which the wearer can view objects forwardly of the enclosure. Enclosure 12 further typically includes a flexible shroud 22 which is fastened around the lower rim of portion 18 and extends downwardly to the chest or waist of the wearer at which location it is generally tied down or otherwise secured to the body to form a more or less airtight enclosure.

Head enclosure 12 is generally used in one of two operational modes, namely;

1. Under conditions where respiration air is supplied to the interior of the head enclosure with the air being at ambient temperature and at a relatively high pressure, such as 90 psi;

2. Under conditions where respiration air is initially cooled by a vortex cooler and is supplied to the interior of the head enclosure at relatively low pressure, such as 2 to 3 psi.

In either of the aforesaid modes, two requirements must generally be met to satisfy certain health and safety conditions. The first requirement is that the volume rate of flow of the incoming air must be maintained within the range of 6 cubic feet per minute to 15 cubic feet per minute and the second requirement is that the noise level of the incoming air must be no greater than 90 db.

Air inlet connection 10 of this invention permits enclosure 12 to operate in either of the above-mentioned modes while assuring that the aforesaid two requirements will be met. To this end, air inlet conncetion 10 includes a tubular fitting 24 which is threadably mounted at its internally threaded upper portion 25 (FIG. 2) onto the externally threaded lower segment 26 of an L-shaped tube 28 leading into the interior of enclosure 12, tube 28 being embedded or otherwise secured to a laterally projecting, hollow boss 30 of face and neck protecting portion 18. Fitting 24 has an intermediate flange 32 which can be engaged by a tool to cause rotation of upper portion 25 of fitting 24 on segment 26.

The externally threaded lower portion 33 of fitting 24 has a generally cylindrical chamber 34 for removably receiving a pair of circular, cellular, sound filtering members 36 and a wire screen disk 38 in the manner shown in FIG. 2. Each member 36 is comprised of open cell plastic foam material, such as vinyl foam. The purpose of members 36 is to break up the incoming air such that the noise level is reduced. Further reduction of the noise level can be achieved inside enclosure 12 by placing a fabric sleeve around the outer surface of the air distribution plenum (not shown) forming a part of enclosure 12. Disk 38 is placed in the downstream part of fitting 24 against a shoulder 39 within the fitting so that the relatively compressible members 36 are not forced into tube 28.

FIG. 2 shows air inlet connection 10 used in the first mode mentioned above. To this end, a source of air under pressure (not shown) is coupled by means of a tube 40 and a fitting assembly 42 to the lower portion 33 of fitting 24. To this end, fitting 42 includes an internally threaded, open top, fitting portion 44 which is threadably mounted around the lower fitting portion 33 of fitting 24. A rubber washer 46 may be used to seal the junction between fittings 24 and 42.

When using enclosure 12 in the first mode, foam members 36 and wire screen disk 38 are first removably inserted into chamber 34, then fitting portion 44 of fitting 42 is threaded onto lower portion 33 of fitting 24 to make a tight connection between the air pressure source and tube 28. Then, air is delivered into enclosure 12 at ambient temperature and at a relatively high pressure.

To change from the first mode of operation to the second mode, fitting 42 is separated from fitting 24 and foam members 36 and wire screen disk 38 are removed from chamber 34. Then, a vortex cooler 48 having an upper, internally threaded, open top, fitting 50 is coupled to fitting 24 by threadably mounting fitting 50 on lower portion 33 of fitting 24. Then, vortex cooler 48 is actuated to allow cool air at a relatively low pressure to enter enclosure 12 through tube 28 and connection 10.

In both of the above operational modes, incoming air is effectively silenced. Also, the size of chamber 34 permits the volume rate of flow of the incoming air to be in the range of 6-15 cubic feet per minute. Fitting 24 can be permanently mounted on segment 26 to allow for a quick changeover from one mode to another.

In the second mode, foam members 36 are removed because their sound reducing characteristic is not required and because they would present a restriction to the incoming air. Such a restriction would cause back pressure against which the vortex cooler could not operate efficiently. Excessive noise is avoided in the second mode because the air enters at a low pressure and because the air distribution plenum has a vinyl sleeve around it.

Claims

I claim:

1. A method for selectively supplying either cooled or pressurized breathing air to a person exposed to a contaminated atmosphere comprising the steps of:

a. providing a head enclosure means defining a substantially closed air space area for surrounding the person's head and including an air inlet for directing breathing air into the interior of said enclosure means;

b. providing a source of relatively high pressure air;

c. providing a source of low pressure cooled air;

d. selectively connecting either said source of high pressure air or said source of low pressure cooled air to said head enclosure means inlet via a dual purpose air inlet connection having a chamber for receiving a sound absorbing member;

e. inserting a sound absorbing member into said chamber from a location outside of said chamber when said head enclosure means is connected to said source of relatively high pressure air and

f. removing said sound absorbing member from said chamber when said head enclosure means is connected to said source of low pressure cooled air.