Air ventilation harness

2,773,262

Dec. 11, 1956

L. A. BROUHA ETAL

AIR VENTILATION HARNESS

Filed Oct. 14, 1954

FIG.l

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LUCIEN A. BROUHA PAUL E. SMITH, JR. JOHN A. ZAPP, JR.

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United States Patent Office

2,773,262

Patented Dec. 11, 1956

2,773,262

AIR VENTILATION HARNESS

Lucien A. Brouha, Kennett Square, Pa., Paul E. Smith, Jr., Arden, Del., and John A. Zapp, Jr., Kennett Square, Pa., assignors to E. I. du Pent de Nemours &amp; Company, Wilmington, Del., a corporation of Delaware

Application October 14, 1954, Serial No. 462,256

Claim. (CI. 2—81)

This invention relates to a device for the protection of human beings exposed to either intense heat or high hupiidity, or combinations of both, with or without simultaneous exposure to irritating or poisonous dust, fumes or gases, and particularly to a personal air ventilating harness which is adapted to be worn by individuals under their regular outer working clothing.

There are many industries, such as the smelting and chemical industries, wherein workers are necessarily exposed to uncomfortably high air temperatures and humidities in the performance of their work, and sometimes the situation is aggravated by the concomitant presence of poisonous or irritating dust, fumes or gases. Also, in some activities, such as surgery, for example, it is necessary to maintain relatively high temperatures and humidities in the operating rooms as a protection for the patients. Hitherto it has been the practice to provide the workers with various types of impermeable outer coverings, such as aprons or even complete suits, as protection. Protective garments of this kind afford temporary protection but, after a relatively short time, there is great discomfort due to perspiration and the gradual increase of temperature of the air adjacent the body. Attempts have been made to incorporate systems of ventilating tubing as an integral part of the working garment but the results have not been altogether satisfactory, since the resulting garments are expensive, stiffened by the tubing tp a degree impeding the free movements of the w.earer and inefficient in cooling air utilization.

An object of this invention is to provide an air ventilation harness which is capable of protecting the user against a potentially harmful, or at least uncomfortable, heat environment. Another object of this invention.is the provision of an air ventilation harness which is low iri cost and which is practically universal as regards sizing. Yet another object of this invention is to provide an air ventilation, harness which can be worn underneath the regular outer garments customarily worn by the user in his vocation and which can be utilized with or without a protecting hood, as conditions require, and which can be worn comfortably when disconnected from the^; cooling air supply if the wearer finds it necessary to leave the high temperature environment in the course of his duties or upon the completion of his work period.

The manner in which these and other objects is accomplished will become apparent from the following detailed description and the illustrative drawings, in which:

Fig. 1 is a partially diagrammatic view of one embodiment of the device according to this invention together with air supply and conditioning apparatus which is adapted for use in conjunction with the harness, and

Fig. 2 is an enlarged section taken on line 2—2 of Fig. 1 showing a preferred relationship of the air supply tubing and its air escape openings with respect to the skin of a wearer.

The apparatus of this invention comprises, in general, a harness fabricated from perforated, strong, flexible tubing, .such as those fabricated from rubber or polymeric ² materials, which is made in such a configuration that cooling and heat-insulating air can be supplied substantially directly to the heat-sensitive areas of the body of the. wearer, thereby shielding him from the effects of δ radiant and conductive heat to a degree maintaining his bodily functions approximately at the level which would obtain for an average person under normal temperatures and conditions, to thereby preserve his health and comfort and conserve his strength. The harness is particu10 larly adapted to be worn with ordinary working clothes utilized in industry, such as the permeable plant type coverall or the like, which is provided with a suitable opening to receive the tube supplying air to the harness, it being preferred that the garment openings for the re15 ccption of the head, hands and feet of the wearer be snug-fitting by the provision of elastic, draw strings, or the like, at collars, wrists and ankles. It will be understood that the apparatus is suitable for wear with impermeable clothing also, however, the results in service 20 tests indicate that impermeable clothing can usually be dispensed with in favor of the more comfortable permeable cloth garments. Where there is exposure to irritating dust, fumes or gases, or relatively high humidity or extremely high temperatures, the apparatus is adapted 25 to use with a detachable air sweep element for the head of the wearer, which can be used in conjunction with a protective hood or the hard hats and safety visors conventionally worn by workers in hazardous occupations. A particular advantage of the apparatus is that, when 30 the wearer leaves the working zone for a rest period or upon the completion of his tour of duty, he can disconnect his harness from the protective air supply and continue. wearing the harness without any discomfort or impairment of freedom of movement until it is convenient 35 for him fo change from his work clothes to street garb.

Referring to Fig. 1, a preferred embodiment of this invention, comprises the . harness circuit consisting of a waist-encircling tube 10, individual arm-receiving loops 11, individual arm feeder lengths 12 and individual leg 40 and foot feeder lengths 13. A head and neck-protective attachment may be optionally employed in conjunction with the body harness, this comprising air supply tube 17 and head-encircling crown piece 18. As illustrated, the harness , may be conveniently assembled by the use of conventional polymeric material fittings, such as the T s 21, the crosses 22 and the connectors 23, which are all adapted to secure, frictional engagement with the sections of tubing constituting the harness, whereby the wearer can easily break any of the connections manually in order gg to don or remove the harness, disconnect himself from the protective air supply or adjust, within limits, the dimensions of the several parts of the harness to a size conforming to his own body dimensions.

Permanently attached cloth tapes, such as those shown ₅₅ at 25, are preferably provided to maintain the arm feeder tubes in fixed position with respect to the arm-receiving loops and permanently attached cloth tape 26 is provided to hold the two loops 11 in fixed position relative one another, tape 26 being intended for location in the small ₆₀ of the wearer’s back in the same manner as a conventional suspenders cross connection. The front sides of loops 11 are optionally provided with conventional buckle and strap elements 27 and 28, respectively, for secure retention of the harness on the wearer’s body, it being ₆- understood that tie strings or the like will serve the purpose equally well, and the arm feeder lengths, and legs and foot feeder lengths are provided near the terminal ends with tie strings 31 integral with the tubing for secure retention of these lengths in desired location with respect to the wearer’s limbs. It is preferred to dispose the arm and leg feeder lengths along the backsides of the limbs, where experience in use has indicated that there is little

2,773,262 or no interference with the free movements of the wearer in the performance of his work.

The harness hereinabove described serves as the air supply system for ventilating the body of the. wearer and is provided with air escape perforations 34, the dispositions of which are best shown in Fig. 2. We have found that the best results as regards wearer comfort and the economical utilization of the ventilating air are obtained if the air sweeps the surface of the skin 36 at a relatively slight inclination with respect to the skin, such as that of angle A represented in Fig. 2. The magnitude of angle A is preferably of the order of 10-15°, under which conditions the wearer receives the maximum benefit of the fresh, cool air on the heat-sensitive portions of the body which it is essential to maintain cool if the worknig efficiency is to be sustained. In this connection, the harness is preferably worn in direct contact with the skin or, in the alternative, on the outside of a light unionsuit or other undergarment which opposes a relatively low resistance to the sweeping action of the air with respect to the body. Experience in the use of the harness has indicated that an air consumption of 10 to 20 C. F. M., depending upon the severity of the exposure environment, is effective in maintaining a high level of wearer comfort. In use, the air supplied through the ventilating harness balloons out the outer garment of the wearer, escaping through the interstices of the cloth, thereby creating an air barrier between the garment and the body while, at the same time, preventing any chafing contact of the outer clothing against the body. So long as the collar, cuff and ankle strictures are comfortably snug a slight gage pressure will be maintained within the suit, thereby barring the passage of toxic dusts, fumes or gases from contact with the body. The ends of feeder lengths 12 and 13 may be closed but, when the harness is used in locations where the hands and feet are subjected to uncomfortably high temperatures, it is preferred to leave the ends open and to use feeders of such length that the ends extend into the gloves or service boots worn by the user, so that the hands and feet are also cooled. The terminal ends of the feeder lengths are preferably disposed on the backsides. of the body members to be protected, in which position they do not interfere with the free use of either the hands or the feet.

As shown in Fig. 1, head crown piece 18, supplied with air through tube 17, is generally circular in. form and may be provided with sponge rubber or felt pad pieces (not shown) to retain its position at about temple level on the wearer’s head, T 39 being disposed to the rear in a position below the back of the wearer’s hard hat or somewhat below the middle of the head-covering expanse of his head. Tube 17 is normally worn outside the. working garment, although it may be worn inside if its passage through the neck stricture does not cause, discomfort or open a bypassing leakage channel for air within the garment. In exceptionally high temperature environments a cross may be substituted for T 39 which cross .is provided with a relatively stiff, flat polymer tube section bent forwardly from the back of the wearers head and open at the end to discharge cooling air across the top of the skull. The ventilation air demand is greatest for the face portion of the body and, therefore, the perforations 34 across the brow portion of the crown piece should be more closely spaced than elsewhere. We have found that good results can be obtained by the employment of a single long air supplying slit, instead of perforations at this location. As is well known the back of the neck is particularly sensitive to heat and, where there is extensive exposure of this region of the body to high temperatures, such as the emission of radiant heat sources, for example, tube 17 is preferably provided with air discharge openings disposed in air-sweeping relationship to the back of the neck, thus supplementing the cooling air supply of crown piece 18,

It will be understood that, if it is not desired to utilize the crown piece with the rest of the harness, the T connection of air supply tube 17 to the main air supply tube may be broken and the crown piece and its supply tube removed, the main air supply tube being then attached directly to the T supplying waist-encircling tube 10.

The air supply for the harness may be conveniently obtained from the permanent plant air supply system indicated generally by pipe 42. The air is first cooled by flow through tubes immersed in an ice bath or otherwise refrigerated cooler 43, after which it may pass through a filter 44 provided with conventional traps or other condensate elimination means, not shown, and thence to a manual pressure regulating valve 45 provided on the downstream side with a pressure gage 46. The connection to the harness is made by a flexible tube 47 which is of a length sufficient to permit the worker to move about freely in his working area without, at the same time, becoming entangled with process equipment or building structural members. If desired, the supply connection may be made from the building ceiling through a trolley arrangement, or in some other wellknown manner assuring the maintenance of the supply tubing in a vertical plane as an additional safeguard against entanglement restriction.

It is desirable to proportion the several tubes making up the harness of this invention with relative dimensions suited to the distribution of air which it .is desired to make to the various body members. Thus, in a typical case, waist-encircling tube 10 was made of ri I. D. tubing with holes on 2 centers, the air supply being derived from a ri” I. D. supply tube 47. The two armreceiving loops and the leg and foot feeder lengths 13 were of % I. D. tubing with holes on 4 centers, whereas the arm feeder lengths 12 were of W I. D. tubing with holes on 4 centers. The ends of the arm and leg lengths were maintained open. The head-encircling crown piece 18 and its supply tube 17 were of % I. D. tubing with holes on 2 centers. All of the holes were ri in diameter.

In a typical test wherein the harness was worn in direct contact with the body, the test subject wearing only shorts with a heavy cotton fabric coverall outer garment, an exposure was made in an experimental room maintained at 110° F. dry bulb and 99° F. wet bulb temperatures, corresponding to a relative humidity of 65%. The subject was tested at rest, during work and during recovery intervals following the work, the work consisting of pedalling a bicycle ergometer for three 10 minute periods with a work load of 2604' lbs./minute.

The subject entered the hot room with his harness in place under the coverall and was connected with an air supply providing a pressure of 8 to 10 lbs. gage with a flow of about 15 to 20 C. F. M. In this test the air was not cooled and entered the harness at a temperature of about 80° F. and a relatively humidity of about 50%. The subject’s condition while at rest was characterized by a heart rate of 92-95 beats/minute and a body temperature of 98.8° F. after 15 minutes of time in the hot room.

At the conclusion of the first 10 minute work period, the heart rate increased to a maximum of 118 beats/ minute at the end of the period. After 15 minutes rest, the heart rate fell to 98 beats/minute. At that time the hood was removed in order to ascertain the physilological difference between breathing cool, dry air and breathing hot, humid air. In the ensuing 5 minutes during which the subject rested without his hood in place, there was no difference in heart rate, but the body temperature rose from 99.1 ° F. to 99.8 ° F.

The second 10 minute work period was undergone without the hood but with air supplied to the harness, and thus to the body of the subject. The heart rate increased to a level of 125 beats/minute, demonstrating the value

2,773,262 of the ventilation effect afforded by the hood, and in the subsequent rest period the heart rate fell only to a level of 108 beats/minute after 15 minutes, i. e., 10 beats higher than after the first exercise and rest periods. In addition, the body temperature rose to 100.3° F. 5 minutes after the second exercise period.

At the end of the second 15 minute rest period the air supply to the harness was discontinued and the subject, without hood, was exposed to the environmental conditions of the test room. There was an immediate increase in heart rate, even with the subject sitting at rest, with a steady rise to 130 beats/minute. During the following exercise period, with no ventilating air supplied to the subject’s harness, the heart rate rose to a maximum of 162 beats/minute after the 8th minute of exercise, when the subject reported his inability to complete the full 10 minutes of the test phase. The subject then rested for an additional 5 minutes in the hot room, during which his heart rate remained above 150 beats/minute and his body temperature reached 101.4° F., at which time he complained of dizziness and was removed from the room and the test terminated.

From the foregoing tests, it was concluded that both work performance and physiological recovery were satisfactory when the complete harness and hood were worn and that, while removal of the hood still rendered vzork feasible, there was a definite strain on both the cardiovascular and thermo-regulating mechanisms. Complete elimination of the air supply to the harness increased the subject’s discomfort and reduced his working ability to the point where further work was impossible.

Other tests were performed in environments in a metallurgical works where the dry bulb temperatures reached as high as 178° F. Workers provided with harnesses and other workers without harnesses were tested after performing their regular tasks. In these tests the ventilation air supplied to the harnesses was cooled to a temperature of approximately 70° F., with a relative humidity of 45%. During these tests protected and unprotected workers performed tasks requiring substantially ⁴⁰ the same physical exertion for successive 10 minute periods, and in all cases it was found that the heart rates of the persons wearing the harnesses were maintained as much as 33½ % below that of the unprotected workers 5 and that, during subsequent rest periods, the rate of recovery, as evidenced by heart rate, was very much faster than for the unprotected workers. In addition, the persons wearing the air ventilating harnesses were dry of perspiration, breathed calmly and demonstrated an 10 appreciably higher productivity in accomplishment of their tasks than unprotected workers. The work performed during these tests was that regularly performed by the test subjects, requiring a high measure of dexterity and bodily freedom, and it was found that the harness 15 and its air supply hose was light in weight, comfortable io wear and not restrictive of free bodily movement.

From the foregoing it will be understood that this invention is capable of rather wide modification without departure from its essential spirit, wherefor it is intended 20 to be limited only by the scope of the f ollowing claim.