IES20050777A2

IES20050777A2 - An improved filter sock

Info

Publication number: IES20050777A2
Application number: IE20050777A
Authority: IE
Inventors: James Walshe; Philip Joseph Hartley
Original assignee: Chem Services
Priority date: 2005-11-22
Filing date: 2005-11-22
Publication date: 2007-05-30
Also published as: GB0623144D0; IE20060837A1; GB2432330B; GB2432330A

Abstract

The present invention is concerned with a filter sock, and in particular a filter sock for use in filtering milk within a milk filtering apparatus or the like, the filter sock including at least a longitudinal edge which is secured together by means of stitching, the filter sock further incorporating a barrier in the form of two length of yarns secured to the sock to occlude the holes created by the needle used in stitching the sock. <Figure 3>

Description

An improved filter sock The present invention is concerned with an improved filter sock, and in particular a filter sock for use with a milk filtering apparatus or the like.

The present invention is particularly concerned with filter socks formed from non-woven materials, which filter socks can be used for filtering a range of liquids, having particular application in the dairy industry for use within milk filtering apparatus.

Generally, a filter sock is comprised of a material which will allow the milk or other liquid to pass through either by direct filtration or by in-direct filtration, but denies passage to sediment or other impurities. In direct filtration, the milk simply enters the sock via the open mouth thereof. The pressure of the milk entering the sock will force the milk from inside the sock to the exterior, thereby filtering the milk.

In indirect filtration, the sock is generally mounted on a frame or cage and the milk is pumped from outside the sock to the interior thereof from which the filtered milk leaves the sock via the open mouth thereof.

For both direct and indirect filtration, the known filter sock comprises a generally rectangularly shaped piece of material suitable for filtering, which .material is folded over on itself so that two opposing I IE 05 0 771 longitudinal edges overlap. The overlap is then stitched. The stitching used may be a simple stitch, for example a lock stitch or a chain stitch, while for an even more secure closure, an overlook stitch may be employed Regardless of the type of stitch used, in order to complete the sock, a similar stitch to that employed on the overlaping longitudinal edges is used along one of the other transverse edges.

Despite the use of even the overlook stitch, the pressure of the milk in the sock and/or the constant movement of the milk acting on the sock when the sock is mounted on the frame stretches the stitching and tends to provide holes which will allow the passage of undesirable sediment of least the low micron size to pass through to the filtered milk. Even without this stretching of the stitching, the size of the thread used to stitch the edges of the filter sock would be in the range of, for example, 100 microns in diameter, whereas the holes produced by the needle used in stitching the seams will generally be in the order of 900 microns in diameter. When the filter sock is formed from a non-woven material, the holes created by the needle in stitching the filter sock do not close over when the material is stretched, as would occur with a woven material. Thus the holes are only partially filled by the thread passing therethrough, and thus leave a significant area for sediment to pass through, reducing the efficacy of such filter socks.

It is an object of the present invention to overcome these problems.

IE 050771 The present invention therefore provides a filter sock which comprises a blank of non-woven material and folded longitudinally upon itself to define a pair of opposing panels; stitching securing together a longitudinal edge of each panel; stitching securing together a transverse edge of each panel at one end of the sock; characterised in that a barrier is provided which substantially occludes holes created in the sock as a result of at least the longitudinal stitching of the sock.

Preferably, the barrier is secured about the holes by means of the stitching along at least the longitudinal edge.

Preferably, the barrier comprises a length of yarn.

Preferably, the barrier comprises a first length of 20 yarn secured in occluding engagement with the respective holes on one panel of the filter sock, and a second length of yarn secured in occluding engagement with the respective holes on the opposite panel of the filter sock.

The present invention also provides a method of making a filter sock which comprises the steps of providing a blank of non-woven material; folding the blank longitudinally upon itself to define a pair of opposing panels; securing together a longitudinal edge of each panel by stitching; securing together a transverse edge of each panel at one end of the sock by stitching; and IE 050 777 securing a barrier in register with holes created in the sock as a result of at least the longitudinal stitching of the sock.

The present invention will now be described with reference to the accompanying drawings, in which; Figure 1 illustrates a plan view of a blank for forming a filter sock according to the present invention; Figure 2 illustrates the blank of Figure 1, folded over on itself to form a pair of opposing panels; Figure 3 illustrates a partial perspective view of the filter sock according to the present invention; and Figure 4 illustrates a sectioned side elevation of a longitudinal stitched seam of the folded blank illustrated in Figure 2.

Referring now to the accompanying drawings, there is illustrated a filter sock, generally indicated as 10, for use in filtering sediment or the like from a fluid, in particular for filtering sediment from milk. The filter sock 10 comprises a blank 12 formed from nonwoven material, which defines a first panel 14 and a second panel 16 which are folded into face to face engagement with one another about a substantially centre line 18. The centre line 18 is positioned to be just off the longitudinal centre of the blank 12,such that one or other of the first panel 14 or second panel 16 project beyond the other, which projecting portion < 05077, can then be folded back to form a seam 20 along one longitudinal edge 22 of the filter sock 10, as illustrated in Figure 2. The seam 20 is then secured or closed, as will be described hereinafter, as is one transverse end of the filter sock 10 to form a closed end 26, leaving an open end 24 into which milk may be introduced into the filter sock 10. The seam 20, and the closed end 26, are preferably secured by means of overlook stitches 28, although other forms of stitching may be employed, for example lock stitches or chain stitches. The configuration of the filter sock 10 as described and shown up to this point is described in the applicant's earlier UK patent GB 2168906, the details of which are incorporated herein by reference.

As described above, as the longitudinal edge 22 and the closed end 26 are stitched, the needle (not shown) creates a linear array of holes 30 in the material forming the filter sock 10, as illustrated in Figures 3 and 4. Referring in particular to Figure 4, it can be seen that during use of the filter sock 10, as a result of the internal pressure arising from the pumping of milk therethrough, the first and second panels 14, 16 are forced outwardly away from one another, exposing the holes 30 to the interior of the filter sock 10.

Thus the holes 30 provide a location at which sediment may escape from within the filter sock 10, in the direction of Arrow A in Figure 4. In order to overcome this problem, the filter sock 10 of the present invention further comprises a barrier in the form a first length of yarn 32 secured in occluding engagement with the holes 30 in the first panel 14, and a second IE 050 777 length of yarn 34 secured in occluding engagement to the opposite end of the holes 30. The first and second lengths of yarn 32, 34 are preferably secured in position by means of the overlock stitches 28 about the seam 20, thereby avoiding the requirement for additional securing means. Furthermore, as each overlook stitch 28 passes through the respective hole 30, a localised portion of either the first length of yarn 32 or the second length of yarn 34 is drawn inwardly into the hole 30, further increasing the efficacy of the barrier. In addition, the use of the stitches 28 to secure the first and second length of yarn 32, 34 ensures that, when the filter sock 10 is in use, the internal pressure increases the tension in the stitches 28 as a result of the separation of the first and second panels 14, 16, again further drawing the yarn 32, 34 into the holes 30. The presence of the yarn 32, 34 occludes each of the holes 30, thereby preventing the escape of sediment therethrough.

It is preferable that the first and second lengths of yarn 32, 34 are formed from a polyester yarn, which has a loose fibrous form, having filter like qualities and being capable of disbursing over a relatively large area in order to ensure that the respective end of the hole 30 is fully filled or covered.

It will therefore be appreciated that the application of the yarn 32, 34 to the filter sock 10 is a simple yet highly effective means of preventing the escape of sediment from the holes 30 left as a result of stitching the sock 10. It will be appreciated that the IE 0$077j holes (not shown) created as a result of stitching the closed end 26 could also be occluded by means of similar lengths of yarn (not shown) applied along the stitch holes of the closed end 26. It will also be appreciated that the yarn 32, 34 used to form the barrier could be replaced with any other suitable equivalent.

The present invention is not limited to the embodiments described herein which may be amended or modified without departing from the scope of the present invention.

Claims

Claims:

1. A filter sock which comprises a blank of non-woven material and folded longitudinally upon itself to define a pair of opposing panels; stitching securing together a longitudinal edge of each panel; stitching securing together a transverse edge of each panel at one end of the sock; characterised in that a barrier is provided which substantially occludes holes created in the sock as a result of at least the longitudinal stitching of the sock.

2. A filter sock according to claim 1 in which the barrier is secured about the holes by means of the stitching along at least the longitudinal edge.

3. A filter sock according to claim 1 or 2 in which the barrier comprises a length of yarn.

4. A filter sock according to any preceding claim in which the barrier comprises a first length of yarn secured in occluding engagement with the respective holes on one panel of the filter sock, and a second length of yarn secured in occluding engagement with the respective holes on the opposite panel of the filter sock.

5. A method of making a filter sock which comprises the steps of providing a'blank of non-woven material; folding the blank longitudinally upon itself to define a pair of opposing panels; securing together a longitudinal edge of each panel by stitching; securing together a transverse edge of each panel at one end of the sock by stitching; and securing a barrier in register with holes created in the sock as a result of at least the longitudinal stitching of the sock.