Garment fabric for handling cryogenic liquids

Abstract

 A material for a glove for handling cryogenic liquids which will not only be effective in preventing contact with cold metal but which will also avoid the risk of holding cryogenic liquid in contact with the skin. If liquid splashes onto bare skin the flash gas released when the liquid approaches (to it) the extremely hot surface of the skin prevents physical contact of the droplet. Consequently liquid which splashes or even flows over our hand for a brief period will not cause injury. This bare skin can be maintained by using a glove manufactured out of a hollow mono-filament fibre such as terylene of about 1 mm in diameter. The fibre can be knitted into a glove shape to form a very open but fairly thick weave. The thickness of material means that cold pipes and fittings can be handled without coming into contact with the skin with the knitted hollow mono-filament acting as an effective thermal insulator whereas any liquid sprayed onto the gloved hand will not be trapped by the "cloth" but may be shaken free.

Description

[0001] This invention relates to a material for use in apparel by those handling cryogenic liquids and to apparel made of such material, particularly (but not exclusively) gloves.

[0002] Because of the risk of cryogenic burns to unprotected skin, it is prudent to wear gloves and other protective clothing when handling cryogenic liquids. Also, the materials often associated with cryogenic liquids, such as metal pipes and fittings, become extremely cold and can cause thermal burns by adhering on contact with unprotected skin. Gloves and other protective clothing are therefore a desirable and indeed normally obligatory protection against such hazards.

[0003] A problem with most such protective clothing arises due to the nature of cryogenic liquids. If liquid cryogen splashes onto bare skin, because the skin is at an extremely high temperature relative to the liquid, the liquid which first contacts the skin flashes off, or vaporises, to form a layer of cryogenic vapour separating the liquid from the skin. This vapour layer effectively insulates the skin from the extreme cold of the cryogenic liquid, and consequently cryogenic liquid which splashes or even flows over bare skin for short periods will not cause injury. However, because cryogens have, in general, very low viscosity they rapidly soak into the fabric, leather or plastic of most forms of protective clothing. This brings the cryogenic liquid into close contact with skin beneath the clothing, and the cloth holds the liquid tightly against the skin and inhibits the flashing off of cryogenic liquid. So, conventional protective clothing, rather than providing an insulating effect and allowing the cryogenic liquid to flash off, instead holds the cryogenic liquid in close contact with the skin so that even if the glove or other clothing is torn off quickly, severe cryogenic burns occur.

[0004] In an attempt to provide gloves suitable for handling cryogenic liquids, gloves have been coated with plastic which is impermeable and thus resistant to cryogen impregnation, but such gloves are prone to crack when in contact with cryogenic liquid, or after prolonged use, and the usual soft fabric cuff which is designed to keep the cryogenic liquid out in practice traps it against the skin. Further, no glove has yet been devised which is suitable for handling both cryogenic liquids and solids at cryogenic temperatures and which can also withstand immersion in a cryogenic liquid and retain its structural and thermal integrity.

[0005] Accordingly, the present invention provides a porous fabric for use in apparel worn by those handling cryogenic liquids, the fabric being formed of a material impervious to cryogenic liquid and being compressible and of sufficient porosity that, in the uncompressed state, the pores allow substantially free passage of cryogenic liquid therethrough, the fabric being sufficiently dense as, when compressed, to provide effective thermal insulation between a solid at cryogenic temperature and human skin.

[0006] Such a fabric, which can be an open-weave or open-knit fabric, or indeed a non-woven fabric, such as a sponge or web, allows cryogenic liquid to flow through and to impact on skin as if the skin were bare. So, cryogenic liquid splashing onto such material worn as clothing will flash off harmlessly much as if the liquid had impacted on unprotected skin. Moreover, any liquid splashing onto the material will tend to drain out quickly, or may easily be shaken free, rather than retained within the material. However, on contact with a solid article at cryogenic temperatures, although the material might compress, the material provides adequate thermal protection to prevent contact between skin and the article, and thus prevents skin adhesion and cryogenic burns.

[0007] Ideally the fabric material is sufficiently resilient, particularly when used for gloves, to compress under the pressure of the wearer's grip, but on release of said pressure to revert, sponge-like, to its normal open-pore condition.

[0008] For the best performance the material should have a low thermal conductivity and may conveniently be a hollow mono-filament fibre such as Terylene® or silicone rubber, woven or knitted to form an open-structured, thick fabric (between about 5mm and 25mm thick, preferably between about 10mm and 15mm thick). The fibres are preferably between about 0.5mm and 1.5mm in diameter, more preferably about 1mm in diameter.

[0009] The drawing shows a schematic view of a glove for handling cryogenic liquids made of material in accordance with the present invention. The glove 2 is manufactured out of a hollow mono-filament terraline fibre of about 1mm in diameter. The fibre is knitted into a glove shape to form a very open but fairly thick weave. The thickness of the material (about 15mm) means that cold pipes and fittings can be handled without coming into contact with the skin of the hand 4, the knitted hollow fibres acting as an effective thermal insulator, whereas any liquid sprayed on to the glove 2 will not be trapped against the skin of the hand 4 by the "cloth" but may be shaken free. An outer impervious layer, such as leather or rubber, may be applied to at least a part of the inner (palm) side of the glove, where there is most abrasion/wear and which is most prone, in use, to suffer splashing of cryogenic liquid. This layer prevents wear and, provided it is not too extensive and the porous structure underneath is sufficiently open, allows any cryogen which penetrates between the layer and the skin to flash off and/or to be easily shaken away.

[0010] Although described in relation to a glove, it will be apparent to those skilled in the art that the material of the present invention may be used to form any type of protective clothing for those handling cryogenic liquids, such as trousers, jackets, hats, underpants and so on.

[0011] For the avoidance of doubt, the term "cryogenic liquid" means a substance which is normally in the gaseous state at ambient temperature and pressure but which is at a temperature below its boiling point at ambient pressure, such as liquid nitrogen or liquid oxygen; the term "cryogenic" should be construed accordingly.

Claims

1. A porous fabric for use in apparel worn by those handling cryogenic liquids, the fabric being formed of a material impervious to cryogenic liquid and being compressible and of sufficient porosity that, in the uncompressed state, the pores allow substantially free passage of cryogenic liquid therethrough, the fabric being sufficiently dense as, when compressed, to provide effective thermal insulation between a solid at cryogenic temperature and human skin.

2. A fabric as claimed in Claim 1 wherein the fabric is an open-weave or open-knit fabric.

3. A fabric as claimed in Claim 1 or Claim 2 wherein the material has a low thermal conductivity.

4. A fabric as claimed in Claim 2 or Claim 3 when dependent on Claim 2 wherein the material is hollow mono-filament fibre.

5. A fabric as claimed in Claim 4 wherein the fibre is between 0.5mm and 1.5mm in diameter, preferably 1mm in diameter.

6. Apparel comprising a fabric as claimed in any preceding Claim.

7. A glove formed of a fabric as claimed in any one of Claims 1 to 5.

8. A glove as claimed in Claim 7 comprising an outer layer of material impervious to cryogenic liquid and extending over at least a part of the inner (palm) side of the hand only.

Drawing