Filter tube for drain purposes

Claim 2

A filter tube for drain purposes, comprising: a tube; openings debouching at the exterior surface of the tube; a central discharge channel in the interior of the tube, said openings capable of being connected to a subatmospheric source through said central discharge channel; at least one flush-channel formed in the wall of the tube and extending at least substantially in the longitudinal direction of the tube, said flush-channel being fully separated from the discharge channel and being able to be connected to a source of pressure fluid at or adjacent one tube end, said discharge channel, openings, and flush-channel arranged to allow simultaneous flushing via said flush-channel and draining through said openings into said central discharge channel; and an outlet for said pressure fluid formed at the other end of the tube.

Claim 3

A filter tube according to claim 1 wherein said flush-channel is connected to a source of pressure fluid.

Claim 4

A filter tube for drain purposes, comprising: a tube; openings debouching at the exterior surface of the tube; a central discharge channel in the interior of the tube, said openings capable of being connected to a subatmospheric source through said central discharge channel; at least one flush-channel formed in the wall of the tube and extending at least substantially in the longitudinal direction of the tube, said flush-channel being fully separated from the discharge channel and being able to be connected to a source of pressure fluid at or adjacent one tube end; an outlet for said pressure fluid formed at the other end of the tube; and a connection head mounted on said one tube end, said connection head comprising an outer cap sealingly engaging the exterior surface of the tube and an inner pipe sealingly engaging the interior surface of the tube, said inner pipe being connected with the outer cap such that a chamber is formed therebetween which may be connected to a source of pressure fluid.

Claim 5

A filter tube for drain purposes, comprising: a tube; openings debouching at the exterior surface of the tube; a central discharge channel in the interior of the tube, said openings capable of being connected to a subatmospheric source through said central discharge channel; at least one flush-channel formed in the wall of the tube and extending at least substantially in the longitudinal direction of the tube, said flush-channel being fully separated from the discharge channel and being able to be connected to a source of pressure fluid at or adjacent one tube end; an outlet for said pressure fluid formed at the other end of the tube; and a connection head mounted on said one tube end, said connection head comprising an outer cap sealingly engaging the exterior surface of the tube and an inner pipe sealingly engaging the interior surface of the tube, said inner pipe being connected with the outer cap such that a chamber is formed therebetween which may be connected to a source of pressure fluid.

Claim 6

A filter tube according to claim 3, wherein a plurality of flush-channels are formed in the wall of the tube and are equally divided over the circumference of the tube.

Claim 7

A filter tube according to claim 3, wherein the discharge channel is closed at an end thereof opposite said connection head.

Claim 8

A filter tube according to claim 4, wherein the wall of the tube includes at least two concentric wall portions, while partitions extend between successive wall portions and laterally adjoin the flush-channels, the openings including perforations in the wall of the tube at the location of the partitions.

Claim 9

A filter tube according to claim 3, wherein this tube is assembled from tube portions, successive tube portions being sealingly connected to each other by means of a connecting element, a spacer member being positioned between the end faces of successive tube portions, which at least substantially uncovers these end faces.

Claim 10

A filter tube according to claim 7, wherein the spacer member comprising a ring having a radial dimension which is small with respect to the thickness of the wall of the tube, said ring being integrally formed with an inner sleeve, which extends over some distance within successive tube portions.

Claim 11

A filter tube according to claim 8, wherein the inner sleeve is connected, e.g. by means of glue, in a lower part of an upper tube portion of successive tube portions, while a part of the inner sleeve positioned underneath the spacer member is provided with external screw-thread, which co-operates with internal screw-thread in the upper part of a lower tube portion.

Claim 12

A filter tube according to claim 9, wherein the connecting element is connected, e.g. by means of glue, to the upper tube portion of successive tube portions and is sealingly connected to the lower tube portion by means of a closing mechanism.