Apparatus for testing the emissions, content or permeability of materials

Abstract

An apparatus for testing the emissions, content or permeability of samples of materials, comprises at least two sample chambers (5a,5b), each in communication with a receiver (9a,9b) for a sorbent trap (10a,10b), a gas inlet conduit (2) having at least two gas delivery conduits (3a,3b), arranged to deliver gas to respective sample chambers, and at least two gas-flow impedance devices (4a,4b), arranged to control the flow of gas through respective sample chambers and through respective sorbent traps. The gas-flow impedance devices preferably comprise a body of porous material and serve to ensure that the rate of flow of gas is substantially the same through each and every sample chamber, regardless of whether a given sample chamber is in use, with a sorbent trap in place or not, or if different sorbent traps are in use for the different sample chambers.

Description

The present invention will now be described by way of examples only, with reference to the accompanying drawings, wherein:

FIG. 1 is a diagram of an apparatus in accordance with the present invention, for use in testing the emissions, content or permeability of materials; and

FIG. 2 is a similar diagram of a modification of the apparatus shown in FIG. 1.

Referring to FIG. 1, there is shown an apparatus generally represented by the numeral 1 and comprising a gas inlet conduit 2 which splits into six gas delivery conduits 3a to 3f. Positioned in the gas delivery conduits 3a to 3f are respective frits 4a to 4f. The gas delivery conduits deliver gas to respective lidded stainless steel sample chambers 5a to 5f having gas inlet ports 6a to 6f and gas outlet ports 7a to 7f. The sample chambers 5a to 5f are placed in a heated aluminium block 8. The outlet ports 7a to 7f are connected to sorbent trap receivers 9a to 9f having respective sorbent traps 10a to 10f fitted sealingly therein.

In use of the apparatus 1 for material emissions and/or content testing, a sample to be analysed is positioned in one or more sample chamber 5a to 5f and sealed therein. A flow of air is introduced into the apparatus 1 via inlet conduit 2. The gas diffuses through the delivery conduits 3a to 3f and through the respective frits 4a to 4. The frits regulate the flow of air such that the rate of flow of gas into the different sample chambers 5a to 5f is substantially the same as each other. Analytes or organic volatiles, if present, are emitted from the samples and the air containing the extracted analytes then passes through the outlets 7a to 7f and into the respective sorbent traps for detection.

In use of the apparatus for permeability testing, a sample of the test material, in generally sheet form, is stretched across the top of a permeation accessory which comprises a well in which a test compound is disposed: the sample of test material is sealed around the perimeter of the permeation accessory and then this placed inside one of the sample chambers 5a to 5f. Clean air/gas is then passed through the sample chambers, as described above: any material emitted by the test compound, and permeating through the sample of test material, is carried by the air/gas flow, into the respective sorbent trap 10a to 10f, for detection. The permeability of the sample to the test compound is thus tested.

Referring to FIG. 2 where like numerals have been used represent like parts, there is shown an apparatus represented by the numeral 101, which differs from the apparatus 1 of FIG. 1, in that the frit 104 is positioned in the gas flow after or downstream of the sorbent trap 110.

The invention is intended to cover not only single embodiments described, but also combinations of the described embodiments for example multiple sample chambers with an alternate air/gas outlet such that air/gas can pass both to the sorbent traps and to vent. In this case the restrictor devices may only control the flow of air/gas into each sample chamber not through the sorbent trap.

It is to be understood that modifications and variations of the present invention will become apparent to those skilled in the art and it is intended that all such modifications will be included within the scope of the present invention as claimed.

Claims

1. An apparatus for testing the emissions, content or permeability of materials, the apparatus comprising: at least two sample chambers, each being in communication with a sorbent trap receiver;a gas inlet conduit having at least two gas delivery conduits, arranged to deliver gas to respective said sample chambers; andat least two gas-flow impedance devices, arranged to control the flow of gas through respective of said sample chambers;wherein said two or more gas-flow impedance devices control the flow of gas through respective sorbent traps disposed in said sorbent trap receivers.

2. An apparatus according to claim 1 for testing the emissions, content or permeability of materials, wherein said two or more gas-flow impedance devices control the flow of gas through respective sorbent traps disposed in said sorbent trap receiver when there is no alternative outlet for the gas except through the sorbent traps.

3. An apparatus according to claim 2, wherein the flow rate through each sorbent trap will be substantially the same irrespective of the number of sample chambers in the apparatus that have sorbent traps disposed in their respective sorbent trap receivers.

4. An apparatus as claimed in claim 1, in which each said impedance device comprises a body of porous material.

5. An apparatus according to claim 4, wherein the body of porous material comprises a frit.

6. An apparatus as claimed in claim 1, in which each said impedance device comprises a restrictor tube.

7. An apparatus as claimed in claim 1, in which said gas-flow impedance devices are disposed upstream of the respective said sample chambers.

8. An apparatus as claimed in claim 1, wherein said gas-flow impedance devices are arranged to be disposed downstream of the respective said sorbent traps.

9. Art apparatus according to claim 1, wherein the impedance presented by the respective gas-flow impedance devices is substantially greater than the total impedance of a path through the sample chamber and the sorbent trap downstream of each respective impedance device.

10. An apparatus according to claim 9, wherein an impedance of flow of the material prior to entering each of said sample chambers is between 10 and 20 times that of the impedance of the material as it passes through the sample chamber.

11. Apparatus according to claim 1 including heating means arranged to heat or maintain each sample chamber at a predetermined temperature.

12. An apparatus according to claim 1, wherein the flow rate through each sample chamber will be substantially the same irrespective of the impedance or said sample chamber and irrespective of whether or not a sorbent trap is disposed in one or more of said sorbent trap receivers.

13. Apparatus according to claim 1, wherein the sample chambers are formed of an inert material.

14. Apparatus according to claim 1, wherein a one-way valve or diffusion locking mechanism is attached to an outlet on the sorbent trap.

15. A method of testing for emissions, content or permeability of materials wherein a sample is fed to at least two sample chambers, each being in communication with a sorbent trap receiver; with gas being delivered to respective of said sample chambers by gas delivery conduits, the gas being delivered to said gas delivery conduits by a gas inlet conduit, with the flow of gas through said respective sample chambers being controlled by at least one gas flow impedance device situated in each of said sample chambers, said gas also being caused to pass through respective sorbent traps in said sorbent trap receivers, to all sample chambers with substantially no impact occurring on the air flow through respective chambers.

16. A method according to claim 15, wherein the impedance presented by the respective gas-flow impedance devices is substantially greater than the total impedance of a path through the sample chamber and the sorbent trap downstream of each respective impedance device.

17. A method according to claim 15, wherein impedance of flow of the gas is between 10 and 20 times that which passes through the sample chamber.

18. A method according to claim 15, wherein the flow rate through each sample trap is substantially the same irrespective of the impedance presented by its respective sorbent trap.

19. A method of testing for emissions, content or permeability of materials according to claim 15 wherein each gas-flow impedance device is positioned upstream of a respective sample device.

20. A method of testing for emissions, content or permeability of materials according to claim 15, wherein each gas flow impedance device is positioned downstream of a respective sample device.

21. A method according to claim 15, wherein gas is caused to flow through two or more sorbent traps in a chamber, which have different impedances.

22. A method according to claim 15, wherein the sample chamber is heated.

23. A method according to claim 15, wherein a one-way valve is in communication with an outlet on a sorbent trap to substantially prevent air or gases flowing back into the sorbent trap before or after vapour collection.