GB2151784A

GB2151784A - Temperature indication

Info

Publication number: GB2151784A
Application number: GB08424442A
Authority: GB
Inventors: Kurt Leichnitz; Joachim Marcoll
Original assignee: Draegerwerk AG and Co KGaA
Current assignee: Draegerwerk AG and Co KGaA
Priority date: 1983-12-23
Filing date: 1984-09-27
Publication date: 1985-07-24
Also published as: JPS60157029A; ES281649Y; IT8409570A0; SE8404530L; NL8402181A; IT1198985B; ES281649U; SE8404530D0; GB8424442D0; FR2557290A1

Abstract

A sealed tube (1) contains an ampoule (4) and a granular indicating layer (5). The ampoule contains, for example, ethylene glycol on silica gel and the indicating layer (5) consists of chromosulphuric acid on silica gel. The glass tube (1) has a predetermined breaking point (8) and is covered with a shrunk-on flexible tube (9) which maintains the tube sealed. On bending the glass tube the ampoule is simultaneously broken and nascent ethylene glycol vapours enter the indicating layer (5) causing a progressive discolouration which is a measure of temperature and time. If the ambient temperature is known, the duration of temperature loads may be ascertained or, if the monitoring period is known, an average temperature may be ascertained. <IMAGE>

Description

SPECIFICATION A method of using a sealed test-tube and a testtube for use in the method This invention relates to a method of using a sealed test-tube, and a test-tube for use in the method, and more particularly to the use of a test tube having a breakabie ampoule as an indicator of temperature load.

In addition to the level of temperature, the duration of temperature load, that is the duration for which an object is subject to a given average temperature, during transportation or storage may also determine quality. This applies, among other things, in the case of chemical systems of analysis, such as gas test-tubes, foodstuffs, pharmaceutics and photographic films.

Test-tubes having a breakable ampoule are known. They consist of one or several filling layers and of an additional reagent ampoule. For reasons of durability or desired reaction, it is not always possible to put all reagent components directly into the test-tube; some of the reagents are then accommodated in an ampoule. In order to use the test-tube, the reagent ampoule is broken and the contents are set free into the test-tube. A flexible tube, which is shrunk onto the test-tube on the outside, holds the fragments together.

As an example, German Patent Specification No.

12 65 454 describes a method and apparatus for simultaneous, selective determination of hydrogen sulphide and mercaptans in gas mixtures. The construction of the test-tube corresponds to that of the above-mentioned test-tube. For the purposes of use, the ends of the glass tube, which have been sealed by melting, are broken and a suitable quan tity of the gas which is to be tested is sucked through the test-tube. The ampoule is then destroyed by sharply bending the test-tube at a predetermined breaking point. The fluid contents of the ampoule are then sucked through the reaction layers. As a result, the presence of the gases which are to be measured is indicated through discolouration.

According to one aspect of the invention there is provided a method of using a sealed test-tube containing (a) an ampoule of a reagent, which ampoule can be broken to release the reagent, and (b) an indicating layer which is in communication with the reagent when the ampoule is broken and which reacts with the reagent to produce a detectable change, the method comprising: breaking the ampoule, the test-tube remaining sealed; and measuring said detectable change after a period of time, this change being dependent on the temperature of the environment and on said period of time.

According to another aspect of the invention there is provided a test-tube for use in a method according to the invention, the test-tube being sealed and containing (a) an ampoule containing a carrier which carries a reagent comprising a vapourizable substance, which ampoule can be broken to release the reagent in vapour form, and (b) an indicating layer which is in communication with the reagent when the ampoule is broken and which reacts with the reagent to produce a detectable change dependent on the quantity of the indicating layer affected by the reagent.

Thus the test-tube, which is not open at the ends, and which has a broken ampoule as an indicator of temperature load, is exposed to the ambient temperature and, after the entry of the vapours which escape from the ampoule, a change, for example a discolouration of the indicating layer, results, this discolouration being dependent upon temperature and time.

Using the test-tube according to the invention, if the ambient temperature is known, the duration of temperature load may be ascertained or, if the monitoring period is known, an average temperature may be ascertained.

In one embodiment, the reagent is ethylene glycol, the carrier is silica gel and the indicating layer is chromosulphuric acid on silica gel.

In another embodiment, the reagent is water, the carrier is silica gel and the indicating layer is blue gel.

The advantages which are achieved with the invention iie particularly in the fact that the problem in respect of an indicator of temperature load operating in a reliable manner based on a measuring medium which has been known for a long time and which is well tested is solved successfully. It is sufficient to break the ampoule and then to arrange the test-tube, which is sealed, in the environment whose temperature is to be monitored. This may be in a casing directly on an object. The discolouration of the indicating layer gives a reliable indication of the temperature load. This may be the actual, average temperature, the period of time and the effects of both these influences.

A delaying layer may be arranged between the ampoule and the indicating layer in which case the indication may be deferred as desired.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying drawing which shows a section through a test-tube in accordance with one embodiment of the present invention.

A test-tube 1, made of glass, has ends 2, 3 which have been sealed, for example by fusion. The glass tube 1 has a predetermined breaking point 8 on a level with the ampoule 4 and is covered with a shrunk-on flexible tube 9. The test-tube contains a filling consisting of an ampoule 4 and of a granular indicating layer 5 which is held between mounting supports 6 which are permeable to gas to prevent vibration. A delaying layer 7 consisting of glass grit is arranged upstream, in the direction of flow of vapour from the ampoule, of the indicating layer 5.

The indicating layer 5 consists of chromosulphuric acid on silica gel as a carrier. The ampoule 4 is filled with ethylene glycol on silica gel as a carrier.

In another form, the ampoule 4 contains water on silica gel as a carrier, and the indicating layer is blue gel.

For the purposes of use, by bending the glass pipe 1 the ampoule 4 is simultaneously broken.

The nascent ethylene glycol vapours enter, in accordance with the effects of temperature and time, through the delaying layer 7 into the indicating layer 5 and there give rise to a progressive, greenish discolouration with conversion into a Cr (III) compound. The length of the discolouration is a measure of the temperature load, that is of the average temperature over a certain period of time.

Claims

1. A method of using a sealed test-tube containing (a) an ampoule of a reagent, which ampoule can be broken to release the reagent and (b) an indicating layer which is in communication with the reagent when the ampoule is broken and which reacts with the reagent to produce a detectable change, the method comprising: breaking the ampoule, the test-tube remaining sealed; and measuring said detectable change after a period of time, this change being dependent on the temperature of the environment and on said period of time.

2. A method as claimed in claim 1, substantially as hereinbefore described with reference to the drawing.

3. A test-tube for use in a method according to claim 1 or 2, the test-tube being sealed and containing (a) an ampoule containing a carrier which carries a reagent comprising a vapourizable substance, which ampoule can be broken to release the reagent in vapour form, and (b) an indicating layer which is in communication with the reagent when the ampoule is broken and which reacts with the reagent to produce a detectable change dependent on the quantity of the indicating layer affected by the reagent.

4. A test-tube according to claim 3, wherein the reagent is ethylene glycol, the carrier is silica gel and the indicating layer is chromosulphuric acid on silica gel.

5. A test-tube according to claim 3, wherein the reagent is water, the carrier is silica gel and the indicating layer is blue gei.

6. A test-tube according to claim 3, 4 or 5, further comprising a delaying layer, disposed between the ampoule and the indicating layer, which delaying layer consists of glass grit.

7. A test-tube substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.