Chemical and biological protective hood assembly
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Chemical and biological protective hood assembly. The hood assembly comprises a head cover portion; a visor; a head passthrough; and an air line passthrough.

Courtney, Mark J. (Middletown, DE, US)
Pheris, Joanne G. (North East, MD, US)
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International Classes:
A41D13/00; A42B1/04; (IPC1-7): A42B1/04; A41D13/00
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1. A hood assembly comprising: head cover comprising at least a barrier film material; visor; head passthrough including neck sealing means; and air line passthrough including air line sealing means.



This application claims the benefit of Provisional U.S. Patent Application 60/549,372, filed Mar. 2, 2004


This invention relates to chemical and biological protective hoods, suits and systems.


Current standard practice for responders to chemical or biological releases is to wear a fully encapsulated suit when using a self contained breathing apparatus (“SCBA”) in a Hazardous Materials (“HAZMAT”) incident requiring vapor protection. In a fully encapsulated suit the responder and the SCBA are completely inside a chemical protective suit to prevent vapor ingress that could contaminate the responder's skin, lungs, etc.

Non-encapsulating chemical and biological protective suits have been under development for several decades, such as those containing a chemical agent-adsorbing material, see for example, WO 83/02066. Many laminate and composite materials have been developed to allow for the transport of water vapor while simultaneously preventing the through-diffusion of liquids and chemical agents. For example, adhesively bonded composites comprising a microporous membrane and a nonwoven fabric, an activated carbon layer, and an inner layer adapted to skin contact is described in WO 93/08024. The technology for protection against chemical and biological assaults while concurrently allowing passage of water vapor to pass has resulted in many useful new composite constructions. For example, U.S. Pat. No. 4,510,193, to Blucher, describes one such sheet material comprised of activated carbon particles adhesively bonded to an air permeable textile.

In HAZMAT incidents where liquid and vapor personal protection are preferred or necessary, the wearer will normally use a SCBA and dress in a fully encapsulated suit, commonly referred to as a Level A ensemble design. The Level A suit will provide complete contamination protection for the wearer, his clothing, and his SCBA. However, the Level A designs tend to restrict user movement and visibility and require the wearer to be completely decontaminated in order to replace their SCBA air storage tank in longer duration operations.

Non-encapsulating garment designs, in which the user wears their respiratory protection outside the garment, provide the user with greater mobility and visibility. However, non-encapsulating designs offering complete skin protection, when worn in conjunction with an SCBA, do not provide sufficient liquid and vapor protection. In searching for designs to improve the liquid and vapor protection when using an SCBA, doffing the garment without compromising the respiratory protection becomes a problem. Many schemes have been attempted, but not succeeded, to eliminate the need of the wearer to disconnect his supplied airline in order to doff a non-encapsulating suit offering vapor and liquid protection for the user's entire body.

Thus, existing systems provide a number of user limitations and force the wearer to choose between functionally limiting designs and designs, which do not offer any substantial amount of vapor and liquid protection. The present invention provides a vapor and liquid protective, non-encapsulating design that insures the chemical and biological protective suit is sealed from ingress of chemical and biological assaults while also allowing for easy donning and doffing and providing for the needs of a supplied air respiratory air system.


The invention comprises a hood assembly for use in protection against chemical and/or biological agents. The hood assembly comprises: a head cover comprising at least a barrier film material; a visor; a head passthrough including neck sealing means at the neck region of a wearer, the neck sealing means being capable of forming a relatively snug fit with a collar-region of the wearer's garment or directly with the wearer's neck; and an air line passthrough comprising air line sealing means, the air line sealing means being capable of forming a relatively snug fit at the surface of an air line which is passed through the air line passthrough and connected to a breathing mask to be worn by the wearer.


FIG. 1 is a front view drawing of a protective hood assembly containing a transparent visor according to the invention;

FIG. 2 is a side view drawing of a protective hood assembly containing a transparent visor according to the invention;

FIG. 3 is a schematic drawing of an air line passthrough according to the invention;

FIG. 4 is a drawing of a further hood assembly according to the invention; and

FIG. 5 is a drawing of a protective coverall assembly according to the inventor.


A chemical and biological protective hood assembly for use with supplied respiratory air systems is provided.

As shown in the Figures, hood assembly is comprised of a head cover 1 comprising at least a barrier film material, such as a fabric construction, that is chemically and biologically protective, a visor 2, a head passthrough 3 including a neck sealing means; and air line passthrough 4 including air line sealing means, through which a supplied respiratory air hose or similar device can be passed and yet sealed against hazardous liquids and vapors.

Suitable barrier film materials include, for example, synthetic film materials such as plastics, rubbers, elastomers, etc. Moreover, preferred barrier film materials include fabric constructions. The barrier film material should provide the necessary level of protection as prescribed by the end application and be sufficiently flexible so as to provide relative comfort and ease of movement to the wearer. Suitable barrier film materials (e.g., fabric constructions) should preferably pass the vapor permeation and liquid penetration tests set forth herein. Although any suitable barrier film material may be used, for simplicity the remainder of the disclosure will refer to fabric constructions. It should be understood that the above mentioned synthetic films are also acceptable according to the invention.

The fabric construction may be comprised of at least one woven or knit or nonwoven textile material and at least one barrier material. The textile may be woven or non-woven, employing synthetic fibers, natural fibers, or blends of synthetic and natural fibers. The textile may also be knits, interlocks and brushed knits. The barrier material may be laminated to the textile, coated onto the textile, imbibed into the textile, or otherwise affixed adjacent to the textile. In an aspect of the invention, fabric construction comprises at least one layer of fabric material and at least one layer of barrier material.

The textile and barrier material may be at least one laminate of at least one fabric layer and at least one barrier film material produced by any suitable method. Suitable methods are known in the art and include those as described in, for example, U.S. Pat. No. 5,289,644 to Driskill et al. For example, such laminates can be produced by printing an adhesive onto one layer in a discontinuous pattern, in an intersecting grid pattern, in the form of continuous lines of adhesive, as a thin continuous layer, etc., and then introducing the second layer in a way that the adhesive effectively joins and adheres together the two adjacent surfaces of an expanded polytetrafluoroethylene (“ePTFE”) based barrier film and the textile material. The first textile layer is typically used to provide abrasion resistance that helps to protect the barrier film material.

An optional second textile layer may be provided on the inside of the fabric construction and is typically present to provide both abrasion resistance to the side of the barrier material opposite the first textile layer and to provide a more comfortable surface to the wearer. The inclusion of a second textile layer creates what is often referred to as a “3 layer” laminate. A 3 layer laminate can be produced by printing adhesive onto both sides of a barrier material and then introducing both a first and second textile to opposing surface of the barrier material onto which the adhesive has been printed. Alternately, a 2 layer laminate can be produced first and then an adhesive printed or otherwise provided onto the barrier material side of the 2 layer laminate prior to the introduction of a second textile layer onto said second barrier material surface.

Alternatively, the textile and the barrier material can be detached from each other except at isolated discrete connection points such as around a perimeter of the article and/or at irregular, sporadic intervals. A 3-layer construction can be accomplished by optionally including a second textile layer on the opposite side of a barrier film(s) from the first textile layer. The second textile layer may comprise a woven, knit, nonwoven textile, or any other flexible substrate comprising textile fibers including, but not limited to, flocked fibers.

The barrier material should be resistant to chemical and biological penetration and diffusion since it provides much of the protective nature of the fabric construction.

A suitable barrier material useful for chemical and biological protective fabric construction is a composite including polytetrafluoroethylene film. Suitable polytetrafluoroethylene containing protective fabric constructions are available from W.L. Gore and Associates under part number ECAT 614001 B. Such protective fabric constructions provide excellent chemical penetration and permeation resistances in addition to high thermal stability, both properties that are required for applications such as fire fighting and hazardous material handling. In addition, the impermeable nature of this type of protective fabric construction provides excellent biological protection, making it ideal for many types of emergency medical personnel. Alternatively, the barrier material used in the chemical and biological protective fabric construction can be any suitable, waterproof, breathable or nonbreathable layer capable of providing the necessary level of protection. For example, the fabric constructions known under the tradename Tychem®fabric (from DuPont) are acceptable.

Turning back to the figures, FIG. 1 shows one aspect of the invention wherein the protective hood assembly is shown to include head cover 1 comprising fabric construction, visor 2, head passthrough 3, and air line passthrough 4. As shown, the protective hood assembly preferably should be of sufficient length so as to extend down over the shoulders of the wearer, as shown by shoulder cover section 11.

Head passthrough 3 includes neck sealing means. Suitable neck sealing means include, for example, an elastic or elastomeric material (e.g., a neck dam), or a stretchable fabric construction such as a stretchable laminate, positioned such that the sealing means will form a relatively snug fit around the wearer's neck or the collar-region of the wearer's garment when worn, yet can be stretched over the wearer's head for donning and doffing of the hood assembly. Further neck sealing means can include, for example, a cinching assembly, such as draw string, hook and loop fastener straps, and elastic straps, for pulling the fabric construction snug about the wearer's neck. Still further neck sealing means includes an inflatable material, such as an inflatable collar that can be inflated to form a seal against the wearer's neck or collar-region. A partially inflatable material where the inflatable material inflates to decrease the diameter of the neck region of the hood such that a relatively snug fit around the wearer's neck is formed can also function as suitable neck sealing means. An even further neck sealing means includes a split-ring assembly that can be closed about the wearer's neck to form a relatively snug fit. The split-ring assembly preferably is a semi-rigid construction comprising plastic, rubber, thin metal, etc., and includes a closure means to enable the split-ring assembly to be donned and doffed easily while also providing a relatively snug fit and a secure seal between the ends of the split ring when closed.

In an aspect of the invention a garment for covering the wearer's torso is provided (such as the coverall depicted in FIG. 5) with a collar 8 that is sufficiently high as to extend around the wearer's neck and above the position of the neck sealing means of the hood assembly. Likewise, the fabric construction of the hood should be designed to extend down over the air line passthrough 4.

Neck sealing means can also be comprised of an elastomeric material such as neoprene, butyl rubber, EPDM, nitrile, chloroprene, fluoroelastomers, etc, that is formed into a suitable circumferential geometry that will allow the wearer to easily slip the hood assembly over his/her head, but still result in a relatively snug fit around the wearer's neck. By “relatively snug” it is meant that the fit around the wearer's neck (or in the case of the air line passthrough, the outside surface of the air line) is sufficiently tight as to provide the necessary protection against the specific threat to which the wearer is to be exposed. For example, if the hood assembly were to be used in an environment that has been chemically contaminated, the “relatively snug” fit would prevent the chemical agent from entering the hood assembly in amounts considered dangerous to the wearer.

The visor 2 of the hood assembly can be any material that is impermeable to the requisite challenges and provides sufficient translucency or transparency and is of sufficient size to allow the wearer to see. The visor can optionally be flexible. A composition of polyvinyl chloride (PVC) and a fluoropolymer film is one such flexible visor material that provides good transparency, excellent chemical and biological penetration resistance, and high thermal stability. In addition, other flexible, polymeric films can be used including but not limited to composites of polycarbonate, fluorocarbon-containing copolymer films, etc. Acrylic-based and vinyl-based films may also be suitable as a visor material for some applications.

Air line passthrough 4 can be a flexible port through which a suitable air supply line can be passed and connected to an air mask to be worn by the wearer. It should be understood that additional passthroughs can be provided to the hood to accommodate further passthrough items. The term “passthrough item” used herein means any item that necessarily extends from the outside to the inside of the hood, such as but not limited to further air supply lines, respiratory air hose, tube, wire, cord, communication equipment line, or other similarly long and flexible material. As shown in FIG. 3, the air line passthrough can be comprised of a flexible protective fabric construction which includes air line sealing means. Air line sealing means can be any suitable means as discussed above with regard to the neck sealing means. For example, in an aspect of the invention, a compressible, elastomeric liner section 9, and a means to secure 10 the elastomeric liner section 9 onto the outer surface of the air line can be used. Moreover, suitable flexible protective fabric construction can be the protective fabric construction described above for use as the hood material. Other flexible protective constructions could also be used as the passthrough. The elastomeric liner section 9 is typically attached to or located on the inner surface of the air line passthrough and should extend circumferentially around the inner surface as to form a ring through which the air line would extend. The securing means 10 can include any type of means capable of forming a relatively snug fit with the air line, such as by forcing the elastomeric liner 9 to be held firmly against the air line. Some suitable securing means 10 include draw-cords (shown in the Figure), clamps, Velcro™ fasteners, and elastic straps, or any other material that can be used to pull the otherwise loose flexible fabric layer/elastomeric liner firmly against the air line. Alternatively, the air line passthrough could have an elasticized end capable of sealing against the outer surface of the air line.

In a further aspect of the invention a seal can be formed across the garment zipper area. Most chemical and biological protective suits require a zipper for donning and doffing. This invention is particularly advantageous in that the neck sealing means can be designed so as to form a relatively snug fit across the zipper area of any garment to be used in combination with the hood assembly. Thus, garments can be designed with zippers that extend to the top of a high collar 8 and yet still form a protective seal.

In practice, the steps for using the protective hood assembly would comprise the following: a wearer would don a suitable protective coverall or jumpsuit (such as coverall 7, shown in FIG. 5); then mount a supplied respiratory air tank on his/her back; next, the wearer should don the respiratory air mask; then the air line from the tank is passed through the air line passthrough and attached to a respiratory air mask, and then air line sealing means are used to seal the air line passthrough against the air line. followed by pulling the protective hood over his/her head. Neck sealing means will provide the relatively snug fit about the wearer's neck or collar of the wearer's coverall.

A second embodiment of this invention is suitable for wear with a respiratory air mask that can accommodate an environmental seal with a chemically and biologically protective hood as shown in FIG. 4. This embodiment is similar to the first embodiment described above except that respiratory mask sealing means 6 is provided for sealing against an outer surface of the respiratory air mask. Further passthroughs are optional. Respiratory air mask sealing means provides sufficient compressive forces to provide a relatively snug fit against the outer surface the supplied air mask. Because the air line to the respiratory air mask does not need to pass from the supplied air tank through the protective barrier layer of the hood assembly, the air line passthrough is an optional feature in this embodiment. Additional passthroughs, however, may be advantageous in that it enables other hoses, lines, wires, and similar things to be safely routed from outside to inside the protective hood assembly. Head passthrough and neck sealing means are also provided in this embodiment.

FIG. 5 shows a suitable garment construction that can be used in combination with the hood assembly. Garment 7 and high neck portion 8 provide a relatively snug fit between a protective hood and high neck portion 8 such that any compressive forces of the neck sealing means do not act to constrict the wearer's neck.

Other ways of ensuring a relatively snug fit between hood and neck portion include a means to hold the neck portion 8 above the neck sealing means of the hood. For example, providing a means for pulling the neck portion 8 closer or even snugly against the wearer's neck, such as providing a hook and loop fastening system (e.g. VELCRO™ fastener) or a cinching means to the neck portion 8 can ensure that the neck portion 8 remains above the neck sealing means of the hood.

In a further embodiment, the protective garment can comprise a semi-rigid, split-ring assembly that encircles the wearer's neck. The semi-rigid split-ring assembly can be either plastic, rubber, or thin metal provided the modulus and design allow for ease of bending while concurrently providing sufficient resistance against any compressive forces of the neck sealing means. A typical construction would have the protective garment 7 affixed to the semi-rigid split-ring assembly and the neck sealing means affixed to the protective hood assembly. The diameters of both the semi-rigid ring assembly and the neck sealing means should be such that the compressive forces between these abutting surfaces are sufficient to provide a relatively snug fit between the neck sealing means and high collar 8.

Closure means can be provided to enable the semi-rigid split-ring assembly to be donned and doffed easily while also providing a secure seal between the ends of this split ring when closed. This closure means can be positioned in line with the zipper area of garment 7 to provide even greater donning and doffing ease while maintaining a satisfactory seal. This split-ring design eliminates the need for a fixed ring assembly that is sufficiently large to fit over the wearer's head, thereby increasing wearer's mobility, comfort, and effectiveness. When used to seal smaller appendages such as wrists and ankles, the split-ring design may be optional. While the inventive elements of this embodiment are as depicted as suitable for use with the chemical/biological protective suits, it is equally applicable to any other protective suit in which there exists a compressive seal formed against the resistive forces of the wearer's body, including but not limited to neck, wrists, and ankles.

In an aspect of the invention, the hood assembly is combined with complimentary protective accessories (i.e. coveralls, gloves, and boots) to form a protective ensemble. The protective ensemble is preferably liquid proof and/or vapor proof. More preferably, the protective ensemble meets the requirements for National Fire Protection Association (“NFPA”) 1994 Class 2 protection.

Further optional embodiments for the protective hood assembly include arm straps 12 which can be provided to the hood to allow for securing the hood to the wearer. For example, nylon straps with locking/unlocking fasteners can be attached to the lower edge of the hood, as shown in FIGS. 1 and 2. Use of such straps (or similar means) will result in keeping the hood in better position while the wearer moves about. Further embodiments can include providing a device or means to relieve any pressure buildup within the hood assembly, such as a check valve, etc.

It may be further desirable to include a moisture management system located or locatable on the inner surface of the hood assembly. During use, it is likely that moisture will be generated in the hood due to, for example, operator perspiration and respirator exhaust discharged into the hood. In order to reduce the amount of moisture inside the hood, a device or multiple devices can be installed on the interior of the hood to collect moisture that is generated during hood use. Moisture can be collected in any number of suitable methods, either by passive or active means. One exemplary means includes a desiccant package in which a desiccant is enclosed in a moisture vapor permeable fabric or other material construction. The desiccant package can be attached to the inside of the hood by several means such as hook and loop fastener, magnetically, adhesively, etc. Favorable properties of the desiccant package would be high moisture vapor permeation, protection of the desiccant from contamination from body oils and salts, containment of the desiccant to the confines of the package, and non-melt characteristics when exposed to high temperatures.


“Barrier material” refers to any material capable of providing permeation resistance against the chemical and biological challenges required for the specific end application.

“Breathable” refers to polymer film/textile laminates that have a Moisture Vapor Transmission Rate (MVTR) of at least about 1,000 (grams/(m2)(24 hours)).

“Non-breathable” refers to polymer film/textile laminates that have a Moisture Vapor Transmission Rate (MVTR) of less than about 1,000 (grams/(m2)(24 hours)).

“Fabric construction” refers to a composite comprising at least one textile material and at least one barrier material.

“Laminate” refers to any layered composite that comprises at least one barrier material layer and at least one textile layer, the layers of which are, typically, adhered together.

By “Adhered” or “Adhered together” it is meant that the barrier material (e.g., ePTFE film) and textile material are joined together by suitable bonding media.

Test Methods

A) Liquid proof shall mean that the hood when worn with complimentary accessories (i.e. coveralls, gloves, and boots) allows no liquid penetration when subjected to a shower spray test such as ASTM F1359. A mannequin is outfitted with a liquid-absorptive undergarment followed by a chemical/biological protective ensemble. The mannequin is then subjected to liquid spray from various angles at specified orientations for a fixed time period. The chemical/biological protective ensemble is then removed and the mannequin is examined. Any evidence of liquid on the liquid-absorptive undergarment as determined by visual, tactile, or absorbent toweling constitutes failure.

B) Vapor proof shall mean that the hood when worn with complimentary accessories (i.e. coveralls, gloves, and boots) allows less than 2% inward leakage when a wearer performs an exercise protocol such as ASTM F1154 while operating in an environment of 1000 ppm sulfur hexafluoride (by volume). NFPA 1994 2001 Edition describes an overall ensemble inward leakage test as a method of quantifying ensemble design vapor protection.

In this test method, sampling ports are affixed at specified positions on the wearer's body. The wearer dons the chemical/biological protective ensemble and tubing connections are then made to sampling pumps that are able to collect samples of air inside the ensemble while being worn. The wearer enters a chamber where a vapor simulant in a concentration of 1000 ppm sulfur hexaflouride (by volume) is present. The user performs a specified exercise protocol, such as described in ASTM F1154, and periodic samples from inside the suit are taken. After multiple iterations of the exercise protocol are performed and interior samples are taken, the samples are then analyzed and the level of sulfur hexafluoride that has entered the ensemble is examined. If the interior ensemble concentration levels exceed 2% of the concentration level present in the chamber, a failure is noted.

An alternative test method is the Man-In-Simulant Test (MIST). The hood, when worn with complimentary accessories to complete the protective ensemble provides a minimum system level protection factor of 50 as tested by the MIST. The MIST procedure may be based on Test Operations (TOP) 10-2-022, Chemical Vapor and Aerosol System-Level Testing of Chemical/Biological Protective Suits (January 2004). Thus, “vapor proof” shall also include hood assembly when worn with complimentary accessories (i.e. coveralls, gloves, and boots) that passes either test described in this section B.

C) “Waterproof” is determined by conducting waterproof testing as follows: Fabric constructions are tested for waterproofness by using a modified Suter test apparatus, which is a low water entry pressure challenge. Water is forced against a sample area of about 4¼ inch diameter sealed by two rubber gaskets in a clamped arrangement. The sample is open to atmospheric conditions and is visible to the operator. The water pressure on the sample is increased to about 1 psi by a pump connected to a water reservoir, as indicated by an appropriate gauge and regulated by an in-line valve. The test sample is at an angle and the water is recirculated to assure water contact and not air against the sample's lower surface. The upper surface of the sample is visually observed for a period of 3 minutes for the appearance of any water which would be forced through the sample. Liquid water seen on the surface is interpreted as a leak. A passing (waterproof) grade is given for no liquid water visible within 3 minutes. Passing this test is the definition of “waterproof” as used herein.

D) Vapor permeation resistance of fabric constructions is determined by ASTM F739, Standard Test Method for Resistance of Protective Clothing Materials to Permeation of Liquids or Gases Under Conditions of Continuous Contact. NFPA standard 1994, Standard on Protective Ensemble for Chemical/Biological Terrorism Incidents, requires ASTM F739 average breakthrough times shall not be less than about one hour for fabrics to be considered permeation resistant to specified chemical challenges.

E) Liquid penetration resistance of fabric constructions is determined by ASTM F903, Standard Test Method for Resistance of Protective Clothing Materials to Penetration by Liquids, for measuring chemical penetration resistance to specified chemical challenges. NFPA standard 1992, Standard on Liquid Splash-Protective Ensembles and Clothing for Hazardous Materials Emergencies, specifies that liquid penetration resistant fabrics shall exhibit no penetration for at least one hour to a specified group of chemicals in order to be classified as liquid penetration protective fabrics.

The following non-limiting example is provided to further exemplify aspects of the invention.


A hood was constructed of three-layer chemical/biological protective fabrics, a chemical/biological protective seam tape, a latex rubber was used as neck sealing means, an optically clear polyvinyl chloride (PVC) film was used as the visor, a 0.045″×1″ open-cell foam rubber tape was used as the air line sealing means, a nylon cording and strapping with locking fasteners was used as the securing means for air line sealing means. The three-layer chemical/biological protective fabrics consisted of a fabric construction from W. L. Gore & Associates (part number ECAT 614001B). Chemical/biological protective seam tape from W. L. Gore & Associates (part number 6HSAJ025BLKBX) was used to seal sewn-together seams. Latex rubber was affixed at the head passthrough as the neck sealing means (part number 30003/1725AS102-4, Formco, Inc). The optically clear PVC visor had a nominal thickness of 0.080 inches was supplied by McMaster Carr (part number 87875K37).

Once the fabric, PVC film, and neck sealing means were tailored to their desired shapes, the pieces were assembled in a logical fashion with the use of a conventional sewing machine. All sewn seams that would be exposed to the outside contaminated environment were sealed with the chemical/biological protective seam tape using a seam tape sealing machine. The end of the air line passthrough was formed by inserting a nylon draw cord through an inner sleeve formed in the fabric, attaching the open-cell foam rubber tape to the inside diameter, and adding cord locking fasteners. Nylon straps with locking fasteners were attached to the outer edges of the hood flaps. Once the user dons the hood, the nylon straps can be pulled under the user's arms and locked to keep the hood in position.