This invention relates to flexible hose. The invention has particular application to flexible hose for use in air conditioning fluid transport in fixed structures, particularly in domestic applications and reference will be made to such application. However, the invention may be found to be useful in other application where fluid transport of similar fluids is desired or required. Accordingly, the term fixed structures is to be taken to encompass domestic, industrial and commercial applications. For convenience, the term "domestic air conditioning" will be used in this specification, and is to be taken to includes commercial and industrial air conditioning unless the context indicates otherwise.

Domestic air conditioning fluid transport is traditionally accomplished with the use of lagged or insulated copper tubing or pipe, normally rigid pipe. Whilst this form of conduit performs well from a technical point of view, copper tubing can be expensive and difficult to install in some locations. Flexible hose is used in some non-domestic air conditioning systems, particularly automotive air conditioning. However, such hose is not suitable for application in domestic air conditioning.

The present invention aims to provide flexible hose which alleviates one or more of the aforementioned problems. Other alms and advantages of the invention may become apparent from the following description.

With the foregoing in view, in one aspect the present invention resides broadly in flexible hose including: a core layer having a lumen extending axially therethrough end en outer surface, the core layer being formed from flexible material suitable for contact with, and prevention of permeation radially therethrough of, domestic air conditioning refrigerant fluids; an adhesive layer formed onto the outer surface of the core layer is sufficient coverage to provide an adhesive layer; a protective layer formed onto the adhesive layer, the protective layer being formed from flexible, compressible and heat insulating material and having an outer resilient surface; a reinforcing layer formed from braided material onto the outer resilient surface to provide an outer reinforced surface; and a finishing layer formed onto the outer resilient surface for protecting the reinforcing layer and retaining same in place on the protective layer. Preferably, the core layer is formed from nylon suited for contact with domestic air conditioning refrigerant such as 1OA, which is a blend of difluoromethane and pentafluoroethane, such as, for example, polya ide 6. The core layer is preferably flexible to the extent that the hose may be bent to a tight radius without kinking. The core layer is selected for form a barrier layer against the permeation of of the refrigerant through the wall of the hose.

Preferably, the protective layer is formed from elastomer, such as nitrile rubber. The rubber may be foamed or softened to provide compressibility and stretchabillty so that the hose may be flexed to follow a tight curve. Preferably, the adhesive layer is formed from material selected for bonding nylon and the material selected for the protective layer, that is, nitrile rubber.

Preferably, the reinforcing layer is formed from cellulosic material, such as rayon, formed in to a braiding, and having a strength sufficient to accommodate the hoop Str ss resulting from the carriage of pressurised fluid. Preferably, the finishing layer is formed from elastomer, such as nitrile rubber. In such form, the protective layer and the finishing layer may be formed from the same material. However, it is preferred that the materials selected for each layer be tailored to their particular purpose. Preferably, the finishing layer is the outermost layer as the material selected does not require further protection. However, it will be appreciated that a further finishing layer may be applied for colouring or aesthetics if necessary, or a metalizing layer may be applied for enhancing the reflectivity of the hose.

In order that the invention may be more readily understood and put into practical effect, a preferred embodiment of the present invention will now be described with reference to the following drawing, and wherein:

Fig. 1 is a partially fragmented perspective view of flexible hose according to the invention.

A flexible hose 10 comprises five layers of different materials, each of which fulfils a different purpose. A core layer 11 has a lumen 12 extending axially through the core to form a core wall 13 which is coaxial with the lumen and the remaining layers. The core layer is formed from nylon for prevention of permeation of refrigerant radially through the core wall - An adhesive layer 14 is formed on an outer surface of the core layer to which a protective layer 15 is formed. The protective layer is formed from flexible, compressible and heat insulating material. A reinforcing layer 16 formed from rayon textile is provided in the form of a braid material onto the outer resilient surface of the to provide an outer reinforced surface. In the particular example illustrated _/ the reinforcing layer is formed from 8-ply rayon to provide burst protection. Ά finishing layer 17 formed onto the outer resilient surface of the braided reinforcing layer for protecting the reinforcing layer.

In use, flexible hose according to the invention may be installed in domestic air conditioning installations in the place of pipe or tubing according to the prior art, or to replace such prior art tubing. Moreover, domestic air conditioning installations previously found to be difficult or impossible may be successfully installed using flexible hose according to the present invention. A prototype flexible hose according to the invention has been tested in experimental trials. When compared to traditional copper pipe used for domestic air conditioning piping, flexible hose according to the invention has been found to have the following advantages: · does not kink, thereby substantially eliminating refrigerant flow restrictions

• does not perish externally • does not break down, even with ozone-safe refrigerants

• has a protective inner lining to prevent contact with rubber or synthetic materials

· substantially eliminates moisture by condensation

• requires no lagging or covering

• is stronger _/ safer and easier to use

• requires no specialised tools or training

• eliminates toxic gasses produced in copper pipe installation

It is further suggested that flexible hose according to the invention may be compared with traditional copper piping as follows:

Copper piping systems have for a long time required the use of specialised tools for the creation of "flaring" to allow the mechanical joining of copper to the compressor units of fridge and air conditioning units. o Flexible hose according to the invention does not require any onsite flaring as the material may bezz manufactured to convenient specified lengths and the flare and retaining device is an integral component of the piping system. Flaring copper requires a degree of accuracy that cannot always be guaranteed to not leak refrigerants to the ozone.

©. All flaring of flexible hose according to the invention is controlled due to the exact nature of machined fittings that are integral with the piping system.

Copper piping systems for refrigerant gases require expert soldering when joining copper products. o Flexible hose according to the invention can be joined in approximately half the time by the incorporation of specialised machined joiners that provide a simple and easy joining method which substantially eliminates leaks.

Copper piping as a result of solder joining requires treatment to remove carbonising that occurs on the copper tubing as a result of soldering processes. o Flexible hose according to the invention does not require solder joints and as such does not need to have carbon deposits removed.

Copper has requirement to be pressure tested after soldering, increasing the labour requirements. o flexible hose according to the invention has a working pressure 3,450 kPa (500 psi) and burst pressure 13,790 kPa (2000 pai) and requires no pressure testing when installed to specifications.

• Copper pipin for fridge or air-conditioning applications requires at least 3-4 tradesman (with specialised training) to route and install copper and taking up to 3 to 4 hours on average for larger installations. o Flexible nature of flexible hose according to the invention piping can be installed by as little as one person (no specialised training) in as fast as 10-15 mins. · Copper piping systems for refrigerants are prone to kinking reducing the efficiency of cooling systems and increasing energy usage. o Flexible hose according to the invention does not kink and retains refrigerant flow volumes thus maintaining energy efficiency.

Copper piping has limitations as to the bends that can be created due to the construction of the product which limits application abilities. o Flexible hose according to the invention has superior flexibility due to the construction of the piping material, thereby enabling much broader installation possibilities. * Copper requires joining to bends and other fittings to turn sharp direction changes increasing cost and labour requirements. o Flexible hose according to the invention is able to be routed through sharp bends without- the need to use bends and joiners and with no kinking.

Copper needs to be deburred prior to joining increasing the labour and skill requirements. o Flexible hose according to the invention needs no deburring as the product comes ready to install and use.

• Copper requires cumbersome insulation to achieve thermal retention o Flexible hose according to the invention is self insulating and retains thermal independence. * Insulated copper has an increased outer diameter that consumes space and reduces application abilities. o Flexible hose according to the invention has a smaller outer diameter increasing the scope of applications available. · Insulation to copper piping can mask areas of perforation to the refrigerant carrying lines. o Flexible hose according to the invention is readily able to be inspected ensuring safe and easy maintenance.

Copper pricing fluctuates according to world mineral pricing . o Flexible hose according to the invention pricing remains consistent.

• Warehousing for Copper packaging size large and bulky and cannot be stacked. Takes up more space in transit vehicles. o Flexible hose according to the invention packaging is small and convenient at approximately 1/4 of the size of conventional copper packaging and can be stacked.

Copper is easily damaged (kinks) and unusable when incorrectly handled. o Flexible hose according to the invention does not kink and cannot be damaged as easily.

* Copper is easily wasted when cut to size so not all of the product is used. o Flexible hose according to the invention is manufactured to convenient lengths that are ready to use with no need for off cuts and waste. Although the invention has been described with reference to a specific example, it will be appreciated by persons skilled in the art that the invention may be embodied in other forms within the broad scope and ambit of the invention as herein set forth and defined by the following claims.