GB2569956A

GB2569956A - Viscometer device

Info

Publication number: GB2569956A
Application number: GB1800051.3A
Authority: GB
Inventors: James Palmer Daniel; James Petitt Oliver; Royston Budd David
Original assignee: BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 2018-01-03
Filing date: 2018-01-03
Publication date: 2019-07-10
Anticipated expiration: 2038-01-03
Also published as: GB201800051D0; GB2569956B

Abstract

A viscometer 10 has a housing 11 within which is an elongate cavity 12 disposed in a horizontal plane of the housing 11. A well 14 is at a first end of the cavity 12 in which a defined volume of a viscous fluid (58a, fig 5a) such as a cornflour thickened liquid, is stored until a releasable retainer 13 is released, allowing progression of the liquid along the channel 12. Following release of the retainer 13, the distance travelled from a starting position 18a of the cavity 12 by the liquid over a set time may be measured against graduations 17 and compared to known viscosity standards to determine the liquid viscosity. The releasable retainer 13 may take the form of a lip (23, fig 3) attached to a lid (25, fig 3) of the housing 11. The cavity 12 may be a curved or spiral shape.

Description

VISCOMETER DEVICE

The present invention relates to a viscometer device, suitable comparatively measuring viscosity of liquids, specifically for thickened foods.

Prior art viscometers fall into two main categories, those that provide absolute values, and those that provide quick comparative tests using known standards.

According to a first aspect of present invention there is provided a comparative viscometer device for measuring the viscosity of a viscous liquid, comprising a housing, having a horizontal plane, within said housing an elongate cavity along which said viscous liquid travels, wherein said elongate cavity lies in said horizontal plane, and said elongate cavity is parallel with said horizontal plane, at a first end of the elongate cavity is a well for storing a defined volumetric aliquot of the viscous liquid to be measured, and a releasable retainer for retaining the viscous liquid in the well.

The prior art comparative viscometers typically comprise a chute which is inclined to provide a gradient, to allow the viscous liquid to be acted upon by gravity. For exceptionally viscous materials this may be useful, however an exceptionally long chute length is required or very short time period in which to measure progress is required, to allow useful measurements to be achieved. The use of a planer, non-gradient elongate cavity allows for shorter path lengths to be achieved. The viscosity of the fluid is a measure of its resistance to deformation by stresses such as, for example shear stress and tensile stress. In this arrangement it is simply the spread of the viscous material to be measured, rather than accelerating the effects due to a potential energy difference in the starting position and finish positon. Therefore the total length travelled may be shorter, when using a non-gravity assisted path.

The viscous liquid, may be a single liquid, blend of two or more liquids, a slurry which comprises a liquid with suspended particulates, emulsion, or an amorphous material in a liquid state.

In a preferred arrangement the viscometer may be portable, such that it can be easily transported about a person, or in pockets of their clothing, apparel or luggage. The housing may further comprise a lid with an aperture, wherein said aperture co-aligns with the well, to allow the well to be filled; without removal of the lid. The remainder of the lid may cover the elongate cavity, and prevent contamination or damage to the elongate cavity. The lid may have a further arrangement, wherein the lid is rotated to provide a locked position, and both the well to be filled and elongate pathway are covered.

The releasable retainer may be any barrier which prevents the viscous liquid from leaving the well and progressing into the elongate cavity, such as, for example a lip, protrusion, plug. The releasable retainer may be removable or rotate out of alignment, it is preferably removable and may be re-usable, such that the releasable retainer provides a liquid tight fit between the well and elongate cavity. The releasable retainer may be any material that provides a liquid tight fit with the well, to prevent egress into the elongate cavity, deformable materials such as polymers, elastomers, rubbers may be used or precision engineering fit rigid materials, such a ground glass, metals or ceramics may be used.

In a highly preferred arrangement the lid may comprise the releasable retainer, such that operation of the lid, causes the removal of the releasable retainer and causes the concomitant defined volumetric aliquot of the viscous liquid to be released into the elongate cavity. The operation may be removal of the lid from the housing or rotation of the lid to allow the releasable retainer to be moved out of alignment and to allow the viscous liquid to enter the elongate cavity. In a preferred arrangement the lid may comprise a lip which protrudes from the edge of the aperture, thereby extending into the well. The lip thereby forms the releasable retainer, such that during the step of filling of the well, the releasable retainer is already in place to prevent spillage into the elongate cavity. Removal of the lid therefore also causes concomitant removal of the releasable retainer, and allows the viscous liquid to move into the elongate cavity.

In a highly preferred embodiment, the viscometer is a portable viscometer, for measuring the viscosity for artificially thickened-food stuffs, to allow people with swallowing difficulties to precisely control the thickness of their liquids. The graduations may be selected to reflect the International Dysphagia Diet Standardisation Initiative flow test. Other uses may be measuring viscosities of engineering fluids, such as, for example lubricants, fuels, hydraulics, oils, to readily determine degradation of said engineering fluids.

Prior art comparative food viscosity devices are typically linear chutes, with a predefined gradient. In order to provide a more compact and portable design, the elongate cavity is a non-linear elongate cavity. In a preferred arrangement the path length of the non-linear elongate cavity may be longer than longest dimension of the housing. Preferably the non-linear elongate cavity has substantially no straight edges or boundaries, such as to prevent stiction or pooling of the viscous liquids to be measured, in angled joints. Preferably the non-linear elongate cavity is curved, spiral, or arcuate.

The progress of the viscous liquid along the elongate cavity is typically determined for a fixed volume (a defined volumetric aliquot) and the total distance measured of said aliquot is measured over a predetermined time period. To aid determination of path length of the distance travelled of said aliquot in the elongate cavity, said elongate cavity, neighbouring guide or wall of said elongate cavity, may comprise graduations to determine progression of the viscous liquid along the elongate cavity.

The housing and therefore cavity walls may be made from any suitable material that does not react with the viscous liquid to be tested. The housing and the lid may be made from the same or difference materials. The materials may be independently selected from metals and alloys thereof, polymers, natural polymers, rubber, paper, and ceramics. Food safe polymers, such as HDPE are particularly preferred. The well and the elongate cavity may be fitted with a disposable liner, such that once the food stuff has been tested the liner may be disposed. The liner may be any food grade material, such as for example polymers, paper. The housing preferably has a first surface which may be rested on a flat surface, the first surface lies in the same horizontal plane as the elongate cavity, thereby ensuring there is no gradient from the well to the elongate cavity.

According to a further aspect of the invention there is provided a method of measuring viscosity of a viscous liquid, comprising filling the well of the device, as defined hereinbefore, with a defined volumetric aliquot of the viscous liquid, removing the releasable retainer means, measuring the distance travelled, along the elongate cavity, of the viscous liquid at a set time interval.

The device may be preferably used to provide comparative data, rather than absolute viscosity measurements. The device may be calibrated with known viscosity standards, and are used as comparators. The distance the viscous liquid has travelled may be measured as function of time. The time period is preferably predetermined.

The distance achieved of the viscous liquid may be observed as a function of time, which may be monitored by eye, and read off against a graduated mark, or detected by a sensor. The final distance achieved (ie total path length) may be compared to a look up table of known viscosities. The sensor may be a video or camera, such as for example a mobile device, to capture the flow of the viscous liquid and calculate the viscosity by comparison charts to other known similar liquids that have been tested as calibration standards.

So that the invention may be well understood, embodiments thereof shall now be described with reference to the following figures, of which:

Figure 1 shows a prior art Bostwick Viscometer

Figure 2 shows a viscometer according to the invention

Figure 3 shows a lid for the viscometer in Figure 2

Figures 4a and b shows a lid engaged with the viscometer

Figure 5a to c show operation of the viscometer.

Turning to figure 1 there is provided a prior art viscometer 1, with a chute 2, a well 4, and operably located between a movable barrier 3. The barrier 3 is moved from the open position (as shown) and put in the closed position and a viscous liquid(not shown) is deposed into the well 4. The barrier is moved to the open position and the viscous liquid travels down the chute 2. The chute is on an incline, and the incline is controlled by operation of the screw threads 6, to raise the well 4 to a higher position with respect to the chute 2.

Turing to fig 2 there is provided a top view of a viscometer 10, comprising a housing 11. The housing 11, comprises an elongate cavity 12, which at a first end contains a well 14. The viscous liquid (not shown-see fig 5) is deposed in the well 14, and the viscous liquid (not shown) is retained by a releasable retainer 13. Upon removal of the retainer 13, the liquid travels from the starting position 18a and progresses towards end of the elongate cavity 18b (the total path length). After a fixed period of time the progression of the viscous liquid may be compared against the graduations 17. The graduations in this example correspond to the International Dysphagia Diet Standardisation Initiative flow test viscosities. This allows the flow of corn starch thickened foods to be rapidly tested. The current test involves the use of syringes or time to “drop of a spoon”.

Turning to figure 3, there is shown the underside of a lid 25, which locates about location aperture 28 on the location peg 39 (see fig 4a) on the housing. The lid 25 has a fill aperture 27, which co-locates over the well 34 (see fig 4a). The fill aperture 27 has a lip 23 which acts as a releasable retainer.

There is a further protrusion 26, which impinges on the well 34, to act as a resistant fit to prevent movement of the lid.

Turning to figure 4a there is a first “ready to receive” arrangement 30 of a lid 35 which is engaged via the location aperture 38 with the location peg 39 of the housing. The fill aperture 37, is in the open position ie allows the viscous liquid to be poured into the well 34. The releasable retainer 33 can be seen protruding into the well to provide a barrier to stop the viscous liquid from entering the elongate cavity, until the desired time. Figure 4b shows the closed position 40, with the lid 45 covering the well, and leaving only a blanking plate 42 which has recesses to allow a resistance fit with the protruding lips (not shown) to prevent the lid detaching from the housing.

Turning to Figures 5a to 5c, shows the stepwise process of testing cornflour thickened liquids for human consumption. The defined aliquot of viscous liquid 58a, an artificially thickened liquid, is transferred via the fill aperture 57 in the lid 55, (the lid being located on the housing 51). The liquid 58a, is filled up to the fill level 59. The lid 55 is removed and in Fig 5c, after a defined period of time the liquid achieves a final progression point 58b in the elongate cavity 52. The progress may then be read off against the graduation marks.

Claims

1. A comparative viscometer device for measuring the viscosity of a viscous liquid, comprising a housing, having a horizontal plane, within said housing an elongate cavity along which said viscous liquid travels, wherein said elongate cavity lies in said horizontal plane, such that said elongate cavity is parallel with said horizontal plane, at a first end of the elongate cavity is a well for storing a defined volumetric aliquot of the viscous liquid to be measured, and a releasable retainer for retaining the viscous liquid in the well.

2. A device according to claim 1, wherein the housing comprises a lid with an aperture, wherein said aperture co-aligns with the well, to allow the well to be filled.

3. A device according to claim 2, wherein the lid comprises the releasable retainer, extending into the well, to form a liquid tight seal, such that operation of the lid, causes the defined volumetric aliquot of the viscous liquid to be released into the elongate cavity.

4. A device according to claim 3, wherein the releasable retainer is a lip which protrudes from the edge of the aperture, thereby extending into the well.

5. A device according to any one of the preceding claims wherein the elongate cavity is a non-linear elongate cavity, such that the path length of the nonlinear elongate cavity is longer than longest dimension of the housing.

6. A device according to claim 5, wherein the non-linear elongate cavity is curved, spiral, or arcuate.

7. A device according to any one of the preceding claims wherein the elongate cavity or housing comprises graduations to determine progression of the viscous liquid along the elongate cavity.

8. A device according to any one of the preceding claims, wherein the housing is made from a material selected from metal, polymers, natural polymers, paper, and ceramics.

9. A method of measuring viscosity of a viscous liquid, comprising filling the well of the device as claimed in any one of claims 1 to 8, with a defined volumetric aliquot of the viscous liquid, removing the releasable retainer means, measuring the distance travelled of the viscous liquid, along the elongate cavity, at set time interval.

10. A method according to claim 9, wherein the device is calibrated with known viscosity standards, and are used as comparators.

11. A method according to claim 9 or 10, wherein the distance is measured as function of time.