GB2276450A

GB2276450A - Tracing liquid flow

Info

Publication number: GB2276450A
Application number: GB9404471A
Authority: GB
Inventors: Richard Chandos Leigh; David Wain Charles
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-03-09
Filing date: 1994-03-08
Publication date: 1994-09-28
Also published as: GB9404471D0; GB9304739D0

Abstract

A tablet for tracing the flow of a liquid comprises a dye and an inert carrier. Utility is in tracing liquid flows in drains, sewers or water courses. Typical dye components are Xanthene or Azo dyes.

Description

DESCRIPTION DRAIN TRACING TABLETS The present invention relates to dyes for the tracing of drains, sewers, water courses or for the flow of any other liquid.

Dyes used for the purpose of tracing the flow of liquids are currently available in two different forms. One of these forms is a paper sachet, similar to a teabag, which contains approximately 9 grams of dye and salt, and when added to approximately 5 litres of water in a suitable container, gives a mixture of dye adequate to undertake a normal test of the liquid flow. Alternatively, dyes are also available as a mixture of dye and salt in powder form, which are sold in polyjars of 200-400 grams, and the user can add his own mixture to a quantity of water in a suitable container.

When considering these existing forms of dye used for tracing the flow of liquids, the paper sachet has an advantage over the loose dye in polyjars, due to the fact that a measured dose of dye is enclosed within each sachet and can be cleanly handled. When using the loose powder, it is difficult for the user to accurately control the amount of dye to be used in testing, and if the test is to be carried out in windy conditions, there is a strong possibility that the powder could be blown from the jar over the user.

Also, if the polyjar is lost during the course of testing, this could mean that in effect 200 grams of dye were used in a solitary test.

There are also disadvantages which are associated with both forms of the prior art mentioned above. One of these problems concerns the level of toxicity of the dye/salt mixture used in both the paper sachet and loose powder. Both forms contain at least fifty percent salt, thus making this mixture relatively toxic and extreme care must be exercised when using this mixture in the environment, especially with regard to fish. Another problem common to both the sachet and loose powder forms, concerns the speed at which the dye is released into the liquid. Both the paper sachet and loose powder forms require that the mixture of dye/salt/water is poured directly into the flow of the liquid to be studied and the dye is then carried at the speed at which that liquid flows.

However, this can cause problems, since many tests require a slow or more controlled release of dye into the liquid.

It is an object of the present invention to provide a mixture of dye and inert carrier suitable for tracing the flow of liquids, which overcomes the aforementioned disadvantages associated with the dye/salt/water mixtures that have been used previously.

In accordance with the present invention, there is provided a dye for tracing the flow of a liquid, which comprises a specified quantity'of dye and inert carrier mixed and formed into a tablet.

As a result of using measured quantities of dye and inert carrier adequate for normal test procedure, which are mixed and then formed into a tablet, the problem is overcome of trying to measure out in the field the requisite amount of dye/loose salt powder mixture which is needed to carry out the test. The formation of the dye and inert carrier into a tablet also counters the problem of this mixture being dissipated by the wind and is therefore clean to handle by the user.

In a preferred embodiment, each tablet comprises a specified proportion or amount of dye and inert carrier. By incorporating an inert carrier into the tablet, the toxicity of the dye mixture to be released is greatly reduced, compared with the previous dye/salt mixture which consisted of at least fifty percent salt.

The production of the tablet can be adjusted so that its solubility or breakdown characteristics are varied in dependence upon the type of study to be undertaken. Thus, by varying the constituent proportions of the tablet and/or by varying its density/compaction, it is possible for the user to obtain a tablet which will dissolve at a required rate, e.g. at a fast rate or at a slow rate, giving the user the opportunity to obtain a correspondingly faster or slower release of the dye into the flow of liquid to be traced.

To this end, the inert carrier can act as a disintegration agent for controlling the rate which the tablet will dissolve in the liquid the proportions of dye and carrier in the tablet and/or its density/compaction determine the disintegration or dissolving of the tablet.

Advantageously the tablet inert carrier comprises crystalline cellulose or natural cellulose.

The tablet may also include a lubricant to assist in preventing the tablet sticking to the dye or mould components during tablet formation. A preferred lubricant is magnesium stearate.

By way of example only, specific embodiments of the present invention will now be described.

A specified quantity of suitable dye, together with either micro-crystalline cellulose or Natural cellulose, and magnesium stearate are mixed together and formed into flat, bevelled edge tablets. It is possible to use a variety of different coloured dyes to be incorporated into each tablet. Microcrystalline cellulose or Natural cellulose are preferred carriers and can be used also as bulking agents to determine the overall size of the tablet and also as disintegration agents, used for controlling the rapid dissolution of the tablet in the liquid. The magnesium stearate is an example of a lubricant for the tablet during the manufacturing - process, for example to prevent the tablet adhering to the moulding components. Each tablet preferably measures approximately 25mm diameter x 9 mm thick and weighs between 4-4.5 grams.

By constructing drain tracing tablets which comprise a mixture of a specified quantity of suitable dye, and for example either micro-crystalline cellulose or Natural cellulose and magnesium stearate, so that they are compacted to have a denser nature, tablets can be achieved which are capable of releasing the dye slowly into the liquid to be traced. Thus, the degree of compaction/density of the tablet can be used to control the rate of release of the dye. This variation in density can be achieved by varying the press pressure and/or press speed during tablet formation.

The invention is not limited to the use of any particular dyes but, in practice xanthene dyes for green and red and Azo dyes for blue and yellow have been found to work well.

The proportions of dye and carrier in the mixture can vary between wide limits but in practice does not exceed beyond the range 75% dye/25% carrier to 25%dye/75% carrier (ignoring the small percentage of lubricant). However, in a typical case the proportions are usually 50/50 (dye/carrier).

In a practical application of how these drain tracing tablets operate the tablet is contained at a position at the head of the liquid flow and the tablet will slowly dissolve, releasing the dye over a period of time. This is extremely useful where the speed of flow of the liquid to be studied is rapid, or where the user wishes to trace the flow of liquid over an extended time.

Claims

1. A device for tracing the flow of a liquid which comprises a specified quantity of dye and an inert carriage agent mixed and formed into a tablet.

2. A tablet as claimed in claim 1, wherein the inert carrier agent acts as a bulking agent to enable the overall size of the tablet to be selected.

3. A tablet as claimed in claims 1 or 2, wherein the tablet inert carrier agent acts as a disintegration agent for controlling the rate at which the tablet will dissolve in said liquid.

4. A tablet as claimed in any of claims 1-3 wherein said inert carrier agent comprises crystalline cellulose or natural cellulose.

5. A tablet as claimed in any of claims 1-4 which further comprises a lubricant.

6. A tablet as claimed in claim 5, wherein the lubricant is magnesium stearate.

7. A tablet as claimed in any of claims 1-6 which is a flat, bevelled edge tablet.

8. A method of tracing the flow of a liquid in drains, sewers or watercourses comprising dissolving a tablet as claimed in any of claims 1-7 in said liquid and tracing the flow of the released dye.

9. A method as claimed in claim 8 wherein the tablet is dissolved at the head of the flow.