Filter device and filter element for use therein

Claim 2

A filter device for use in a pipeline flow system, which device comprises a separable two part housing defining a filter chamber enclosed but for the provision of a fluid inlet and fluid outlet of substantially the same cross sectional area oppositely disposed in end portions of the parts of the housing, the housing containing between the fluid inlet and the fluid outlet a plurality of circular flat filter elements of decreasing mesh size for successively filtering out particles of decreasing size, which filter elements each comprise, set in an annular frame, which frames are clamped in a stack between the end portions of the parts of the housing a first substantially inextensible plastic filter mesh, the size of which filter mesh is decreased in the flow direction down to a finest mesh size of from 40 to 80 microns, and a second and coarser substantially inextensible plastic filter mesh having a mesh size in the range of from 160 to 950 microns and serving as a support mesh positioned on the downstream side of each filter element, which support meshes are coarser than the coarsest said first mesh and which meshes when the filter device is not in use, are generally out of contact with the or each adjacent mesh.

Claim 3

A filter device as claimed in claim 1, wherein the said meshes are formed of woven filaments of a plastic material selected from the group consisting of nylon, polypropylene, polystyrene, polyester and PTFE.

Claim 4

A filter device as claimed in claim 1, wherein the casing is formed of a methyl pentene polymer.

Claim 5

A filter device as claimed in claim 1, wherein the support meshes have a mesh size of from 250 to 950 microns and the filter meshes positioned thereadjacent have mesh sizes decreasing from about 140 to 200 microns at the coarsest filter mesh to about 50 to 70 microns at the finest filter mesh.

Claim 6

A milking system for effecting simultaneous milking of a plurality of animals and supply of the milk yield of the animals to a storage tank, which system comprises a weigh jar, a flow system for supply of milk from the animals to the weigh jar and a pipeline from the weigh jar to the storage tank incorporating a supply pump and a filter device, which filter device comprises a separable two part housing defining a filter chamber enclosed but for the provision of a fluid inlet and fluid outlet of substantially the same cross sectional area oppositely disposed in end portions of the parts of the housing, the housing containing between the fluid inlet and the fluid outlet a plurality of circular flat filter elements of decreasing mesh size for successively filtering out particles of decreasing size, which filter elements each comprise, set in an annular frame, which frames are clamped in a stack between the end portions of the parts of the housing, a first substantially inextensible plastic filter mesh, the size of which filter mesh is decreased in the flow direction down to a finest mesh size of from 40 to 80 microns, and a second and coarser substantially inextensible plastic filter mesh having a mesh size in the range of from 160 to 950 microns and serving as a support mesh positioned on the downstream side of each filter element, which support meshes are coarser than the coarsest said first mesh, and which meshes, when the filter element is not in use, are generally out of contact with the or each adjacent mesh, the filter device being disposed in the pipeline with the first mesh of coarsest mesh being upstream and the first mesh of finest mesh being downstream.

Claim 7

A milking system for effecting simultaneous milking of a plurality of animals and supply of the milk yield of the animals to a storage tank, which system comprises a weigh jar, a flow system for supply of milk from the animals to the weigh jar and a pipeline from the weigh jar to the storage tank incorporating a supply pump and a filter device, which filter device comprises a separable two part housing defining a filter chamber enclosed but for the provision of a fluid inlet and fluid outlet of substantially the same cross sectional area oppositely disposed in end portions of the parts of the housing, the housing containing between the fluid inlet and the fluid outlet a plurality of circular flat filter elements of decreasing mesh size for successively filtering out particles of decreasing size, which filter elements each comprise, set in an annular frame, which frames are clamped in a stack between the end portions of the parts of the housing, a first substantially inextensible plastic filter mesh, the size of which filter mesh is decreased in the flow direction down to a finest mesh size of from 40 to 80 microns, and a second and coarser substantially inextensible plastic filter mesh having a mesh size in the range of from 160 to 950 microns and serving as a support mesh positioned on the downstream side of each filter element, which support meshes are coarser than the coarsest said first mesh, and which meshes, when the filter element is not in use, are generally out of contact with the or each adjacent mesh, the filter device being disposed in the pipeline with the first mesh of coarsest mesh being upstream and the first mesh of finest mesh being downstream.

Claim 8

A milking system as claimed in claim 5, wherein the filter device contains a plurality of substantially flat said filter elements, the filter elements each comprising a pair of filter meshes connected together at their edges, one mesh of each element being a support mesh for the other and having a larger mesh size than the other mesh, the support meshes having a mesh size of from 250 to 950 microns and the filter meshes having a mesh size decreasing from about 140 to about 250 microns at the coarsest filter mesh to about 50 to 70 microns at the finest filter mesh.

Claim 9

A milking system as claimed in claim 6, wherein the said meshes are formed of woven filaments formed of plastic material selected from the group consisting of nylon, polypropylene, polystyrene, polyester and PTFE.