Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
46 words
A gaseous diffusion resistant tube comprising a core of a liquid resistant plastics material and an outer layer of a plastics impact resistant material,characterised by an intermediate layer of a gaseous diffusion resistant plastics material interposed between and bonded to the core and the outer layer.
Claim 2
Dependent Claim
46 words
A gaseous diffusion resistant tube comprising a core of a liquid resistant plastics material and an outer layer of a plastics impact resistant material,characterised by an intermediate layer of a gaseous diffusion resistant plastics material interposed between and bonded to the core and the outer layer.
Claim 3
Dependent Claim
30 words
A tube according to claim 1 wherein the core and the outer layer have substantially similar coefficients of linear expansion and the intermediate layer has at least a slight elasticity.
Claim 4
Dependent Claim
21 words
A tube according to claim 1 or claim 2 wherein the core at least is made of a cross-linked polyolefinic material.
Claim 5
Dependent Claim
17 words
A tube according to claim 3 wherein the onter layer is also made of a polyolefinic material.
Claim 6
Dependent Claim
18 words
A tube according to either of claims 3 or 4 wherein the cross-linked polyolefinic material is cross-linked polyethylene.
Claim 7
Dependent Claim
30 words
A tube according to any one of the preceding claims wherein the intermediate layer is also adhesive to the material forming the core and the material forming the outer layer.
Claim 8
Dependent Claim
18 words
A tube according to claim 6 wherein the intermediate layer is selected from polyvinylalcohol, polyacrylonitrile or polyvinylidene chloride.
Claim 9
Dependent Claim
18 words
A tube according to any preceding claim wherein the intermediate layer has a thickness between 60p and 10µ.
Claim 10
Independent Claim
46 words
A method for the production of a tube according to any one of claims 1 to 8 which comprises sequentially forming the core layer, the intermediate layer and the outer impact resistant layer in coaxial array such that said layers are fused together at their interfaces.
Claim 11
Dependent Claim
14 words
A method according to claim 9 wherein the forming step is effected by coextrusion.
Claim 12
Dependent Claim
29 words
A central heating system incorporating a tube as claimed in any one of claims 1 to 8 or made by the method of either of claims 9 or 10.