WO1992004835A1

WO1992004835A1 - Improvements in or relating to protective garments

Info

Publication number: WO1992004835A1
Application number: PCT/GB1991/001702
Authority: WO
Inventors: Robin Middlemass Howie
Original assignee: Institute Of Occupational Medicine Limited
Priority date: 1990-09-25
Filing date: 1991-09-25
Publication date: 1992-04-02
Also published as: GB2248173A; ZA917662B; GB9020879D0

Abstract

A protective garment including a suit (2) for encapsulating substantially the whole of a wearer's body has an air conditioning unit (8) including a fan (10), a power pack (14) and a water vapour absorbent/adsorbent element in the form of a canister (12), and optionally a filter (16). An air path selector comprising a multi-way valve (20) is provided and allows a wearer to alter the air path within microclimate of the suit. In one operational mode, the air path follows an open circuit from the external environment through the filter, circulating within the microclimate and exhausting to the environment. In another operational mode, the microclimate is isolated from the external environment and the air path is a closed circuit, the air passing through the canister.

Description

IMPROVEMENTS IN OR RELATING TO PROTECTIVE GARMENTS

This invention concerns improvements in or relating to protective garments of the kind employed in contaminated environments.

Protective garments are widely used to prevent the interchange of contamination between the wearer's body and the environment. Currently the performance of protective garments is limited by such mechanisms as contaminant penetration of the garment's fabric, seams, fasteners or of the seals between the garment and the body. The control of such penetration is limited to the body's critical requirement to lose the heat generated by metabolic process and this requirement increases with the work rate of the wearer. A minor restriction in the heat loss ability can cause discomfort and a possible reduction in the wearer's mental and physical efficiency. A major restriction can result in excessive sweating, coma or death. When excessive sweating occurs, the relative humidity in the microclimate between the garment and the wearer's body approaches 100 per cent. Consequently, sweat evaporation, the major mechanism by which the body loses heat, largely ceases, and heat storage by the body begins. It is generally accepted that deleterious health effects can occur when the body temperature increases by more than about 1° C.

An earlier Patent Application No 2 219 486A describes a means of reducing the thermal stress generated by wearing a protective garment by recirculating hot humid gases from the microclimate between the garment and the wearer's body through a water vapour absorbent/adsorbent thereby reducing the relative humidity in the microclimate and thus permitting further evaporation of sweat.

Although that prior art protective garment is highly effective, its applicability is limited by the capacity of the water vapour absorber/adsorber. When protective garments have to be worn, three distinct phases of wear can be postulated: the period between fitting the garment and actually being exposed to substances hazardous to health; the period while exposed to substances hazardous to health; and the period between exposure and removal of the garment. During the third period and upon removal of the garment, exposure to the substances hazardous to health could occur by virtue of garment contamination.

It will be appreciated that the period of actual exposure to the substances hazardous to health may be substantially shorter than the total period during which the garment is worn. For example, in the military context of possible exposure to chemical weapons, protective garments may require to be worn for many days while threatened by the use of chemical weapons. During such periods, it is clearly essential that the protected personnel are able to function efficiently without undue risk to health as a result of wearing protective garments.

An object of the present invention is to provide an improved protective garment having the capacity to extend the applicability of that described in British Patent Application No 2 219 486A and in so doing to offer a means of further reducing the possibility of the body storing heat and thereby effecting an improvement in the wearability of protective garments.

According to the invention there is provided a protective garment for use in a hazardous environment including a suit for encapsulating substantially the whole of a wearer's body and thereby defining a microclimate therewithin around the wearer's body, an air inlet to the suit, an air outlet from the suit, a conditioning unit mountable on or in the suit, the unit including an air mover, a power pack for the air mover, a water vapour absorbent/adsorbent element, and an air path selector for selecting the air path within or through the suit.

Whilst the conditioning unit is mountable on or in the suit, it is to be understood that the unit might in certain situations be mounted remote from the suit. Conveniently the conditioning unit is self-contained, may be optionally body-mounted and incorporates the air mover, the power pack and the water vapour absorbent/adsorbent element, a filter optionally being included. Alternatively, the filter may be separately mounted on the suit.

Advantageously the airpath selector comprises a multi-way valve actuable in one mode to permit air flow into the suit via the inlet for circulation within the microclimate in an open circuit and subsequent exhaust through the outlet from the suit. In this mode, the filter, when provided, filters air entering the microclimate. The filter may be of a type for removing particulates and/or noxious gases or vapours.

The multi-way valve in another mode is actuable to isolate the suit from the surrounding environment, thereby causing air flow within the microclimate alone through the water vapour absorbent/adsorbent element in a closed circuit.

The air path selector may be actuable manually in response to a change in the environment or may be actuable automatically in response to such a change. In this latter respect, a detector may be provided externally of the garment and capable of transmitting a control signal to the selector to change its mode.

The outlet from the suit may itself be provided with a non-return valve and/or an outlet filter and optionally may be closed by the multi-way valve when operating in the closed circuit mode.

Conveniently, ducts may be provided for delivering dried or filtered air from the air mover to the most appropriate regions within the microclimate of the suit, and for removing humid air from the regions.

The multi-operational modes of the air path selector confer upon the garment the ability to control the manner of usage dependent upon the prevailing environmental circumstances, thereby affording the opportunity to regulate the rate at which the water vapour absorbent/adsorbent element is spent and thus its active life. βy way or example only, one embodiment of protective garment according to the invention is described below with reference to the accompanying drawings in which:

Figure 1 is a digrammatic representation of the protective garment; and Figure 2 is a diagrammatic representation of a detail shown in Figure 1.

Referring to the drawings, a protective garment for use in a hazardous environment is shown generally at 2 and comprises a one- piece suit or a multi-piece suit (not shown) which encapsulates most of the wearer's body 4 as illustrated, with appropriate sealing provided as required such as at the ends of the limbs, and, in suits not fitted with head covers, at the neck, a microclimate thereby being defined between the wearer's body and the enclosing suit. The suit has an air inlet 6 and an air outlet 7.

Located within the volume of the garment 2 is a self-contained unit 8 incorporating an air mover in the form of a fan 10, a canister 12 containing water/water vapour absorbent/adsorbent material, and a power source, for example a battery pack 14. The unit 8 also includes a filter 16 associated with the inlet 6 for filtering incoming air. The unit 8 is conveniently carried as on a belt 17 by the wearer. Additionally, but optionally, ducts 18 may be connected to the fan 10 for distributing air within the garment, namely for delivery of conditioned air to and for withdrawal of hot humid air from the regions of high vapour generation.

The unit 8 also includes an air path selector in the form of a multi-way valve 20 which is operational in at least two modes as described in the following text. The valve 20 is either manually actuable or automatically actuable in response to a signal from a detector (not shown) which is capable of monitoring the atmosphere for noxious or chemically injurious, or fatal, substances.

In operation, the suit 2 is worn as a garment for the protection of an individual working or serving in an atmospherically hostile and potentially injurious or even fatal environment. However, the environment might prove to be intermittently hostile rather than continuously so and accordingly the garment of the present invention has been conceived with a view to providing the individual wearer with two operational modes. If, for example, the garment is worn with the expectation that at any time the environment could become hostile, the individual wearer will wish to remain in the garment in as safe and as comfortable a manner as possible. Accordingly, the valve 20 is actuated such that upon operation of the fan 10, air is induced into the suit 2 through the inlet 6 and the filter 16, the air thence passing through the ducts 18 to the parts of the body where sweat generation is potentially the greatest, for example the axillary regions among others. The air thus flows through the microclimate and becomes humid, the water vapour-laden air exhausting through the outlet 7. In this mode the air by-passes the canister 12.

If the surrounding environment in which the individual wearer finds himself becomes hostile in an atmospheric sense, the valve 20 is actuated to assume its alternative mode in which the air inlet 6 and the air outlet 7 are closed, and the air path within the microclimate is constrained through the canister 12, the air being conditioned by the absorbent/adsorbent material and recirculated by the fan 10 through the ducts 18 in the manner described above, the ducts delivering conditioned air to and withdrawing hot humid air from the regions of high water vapour generation. The valve 20 closes the outlet 7 to prevent loss of gases from the microclimate when operating in the closed circuit mode since if this closure were not effected a negative pressure could obtain within the suit with adverse results.

The advantage of the present invention resides in its operational versatility in providing the wearer of the garment two options. The one involves simple air irrigation of the suit from an innocuous external environment through a filter to the microclimate for circulation therewithin and exhaust to the environment. The other provides for circulation and recirculation of air within the microclimate, the air being passed through a water vapour absorbent/adsorbent, when a hostile environment prevails without the garment.

Claims

CLABΛS

1. A protective garment for use in a hazardous environment including a suit for encapsulating substantially the whole of a wearer's body and thereby defining a microclimate therewithin around the wearer's body, an air inlet to the suit, an air outlet from the suit, characterised by a conditioning unit mountable on or in the suit, the unit including an air mover, a power pack for the air mover, a water vapour absorbent/adsorbent element, and an air path selector for selecting the air path within or through the suit.

2. A protective garment according to claim 1 characterised in that the conditioning unit is self-contained and incorporates the air mover, the power pack and the water vapour absorbent/adsorbent element.

3. A protective garment according to claim 1 or 2 characterised in that the conditioning unit includes a filter which in use is associated with the inlet.

4. A protective garment according to any one of the preceding claims characterised in that the airpath selector comprises a multi-way valve actuable in one mode to permit air flow into the suit via the inlet for circulation within the microclimate and subsequent exhaust through the outlet from the suit.

5. A protective garment according to claim 4 characterised in that the multi-way valve in another mode is actuable to isolate the suit from the surrounding environment, thereby causing air flow within the microclimate alone through the water vapour absorbent/adsorbent element in a closed circuit.

6. A protective garment according to claim 4 or 5 characterised in that in which the multi-way valve is operable manually.

7. A protective garment according to claim 4 or 5 characterised in that the multi-way valve is operable automatically in response to a change in the environment monitored by a detector either associated with the garment or remote therefrom.

8. A protective garment according to any one of the preceding claims characterised in that ducts are provided for delivering dried or filtered air from the air mover to the most appropriate regions within the microclimate of the suit and for withdrawal of hot humid air from the regions.

9. A protective garment according to claim 8 characterised in that the ducts are formed in an undergarment to be worn beneath the garment.

10. A protective garment for use in a hazardous environment including a suit for encapsulating substantially the whole of a wearer's body and thereby defining a microclimate therewithin around the wearer's body, an air inlet to the suit, an air outlet from the suit, characterised by a conditioning unit mountable remotely from the suit, the unit including an air mover, a power pack for the air mover, a water vapour absorbent/adsorbent element, and an air path selector for selecting the air path within or through the suit.