FIELD OF THE INVENTION

This invention relates to an apparatus for testing for potential airborne respirable fibres in a test sample.

PRIORITY

This patent application claims priority from:

Australian Provisional Patent Application 2010900805, titled "AIR FIBRE TESTING APPARATUS", and filed on 25 February 2010; and

Australian Provisional Patent Application 2010903586, titled "AIR FIBRE TESTING APPARATUS", and filed on 11 August 2010.

The entire content of these applications is hereby incorporated by reference. BACKGROUND OF THE INVENTION

The main application for the present invention is in relation to the testing of soil samples for potential airborne respirable fibres. This testing may be onsite or laboratory testing.

It is necessary to determine whether the soil samples taken during mineral exploration processes have the potential to release airborne respirable fibres (particularly asbestos) should a given site become a fully operational mine site. This is critical to determining whether a given site is safe and/or at least viable for further exploration or mining.

For example, as part of their risk assessment process, iron ore mining companies operating in the Pilbara Region of Western Australia regularly assess the potential presence of respirable asbestos fibres in percussion drill samples taken during mineral exploration or blast hole drilling.

One device currently used in Australia for the testing of these samples is referred to as the 'Coffey Rocket'. This comprises a tube into which a solid sub-sample of the material is placed, this sample is then blasted with high pressure air to create an atmosphere of pressurised dust inside of the tube that can be sampled and tested.

A problem with the Coffey Rocket however is the risk associated with the positively pressurised dust, and the real potential for this to be leaked to the atmosphere and inhaled by an operator of the device. It is an object of the invention to provide a testing apparatus that ameliorates one or more of the above stated difficulties, or which at the least provides a useful alternative to known testing devices, such as those discussed above.

Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. SUMMARY OF THE INVENTION

In one aspect, the invention may be said to reside in an apparatus for testing of soil samples for potential airborne respirable fibres, the apparatus comprising a sealable sample agitator, a sealable chamber into which dust is drawn from the sample agitator by a source of vacuum, and an air sampling means.

In one aspect, the invention may be said to reside in an apparatus for testing of soil samples for potential airborne respirable fibres, the apparatus comprising a sealable sample agitator, a sealable chamber into which dust is drawn from the sample agitator by a means creating a negative pressure in the sealable chamber, and an air sampling means.

In one form, the air sampling means provides the source of vacuum.

In one form, the air sampling means is an air sampling pump. In one form, the sample agitator comprises a sealable opening so that the internals to this can be accessed.

In one form, the sealable chamber comprises a sealable opening so that the internals to this can be accessed.

In one form, the sealed chamber is an elutriator having an inlet into which dust is drawn from the sample agitator, a first outlet to an air sampling pump, and a second outlet to a source of vacuum.

In one form, in an alternative, the sealed chamber is an elutriator having an inlet into which dust is drawn from the sample agitator and an outlet to an air sampling pump. In one form, the elutriator having an outlet to an air sampling pump comprises a sampling medium.

In one form, the sample agitator is a nimbler.

In a further aspect, the invention may be said to reside in an apparatus for testing of soil samples for potential airborne respirable fibres, the apparatus comprising a sealable sample agitator, and a sealable chamber into which dust is drawn from the sample agitator by an air sampling means. In a further aspect, the invention may be said to reside in an elutriator tube having an inlet and an outlet, and a sampling medium located inside of the tube between the inlet and the outlet.

In one form, the inlet, outlet and sampling medium are aligned. In a further aspect, the invention may be said to reside in a method for using the above described apparatus, the method including the steps of agitating the sample in the agitator to create a dust, using the source of vacuum to draw dust from the sealed sample agitator, and then using the air sampling means to test the dust for respirable fibres. In one form, the method comprises the further steps of using the source of vacuunragain when air sampling is completed, to substantially capture the dust prior to opening the elutriator.

In this respect, before explaining at least one exemplary embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawing. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of this disclosure it will now be described with respect to an

^exemplary embodiment which shall be described herein with the assistance of drawings, wherein:

Figure 1 is a schematic illustration of an on site testing apparatus according to an exemplary embodiment;

Figure 2 is a schematic illustration of an on site testing apparatus according to a second exemplary embodiment; and Figure 3 is a schematic illustration of an elutriator tube from the apparatus illustrated in Figure

2.

DESCRIPTION OF A PREFERRED EMBODIMENT

In Figure 1 , there is illustrated an apparatus 1 for testing of soil samples for potential airborne respirable fibres.

The apparatus 1 comprises a base plate 2 upon which there is mounted a sealable sample agitator in the form of a rumbler 4 and a support column 6 for an elutriator 8. The support column 6 can be detached from the base 2 (with the elutriator 8 attached thereto) so that the apparatus 1 can be folded down into a case for transport.

The rumbler 4 has opposing sealed ends and contains three ball bearings to assist in the breaking of the sample and the creation of dust in the rumbler as this rotates. A first end of the rumbler is connected via swivel fitting 6 and conduit 7 (such as tygon tubing) to a 5L/min rotameter 10. The second sealed end 4b of the rumbler 4 is connected via a swivel fitting 12 and conduit 14 to an inlet 16 at a lower end of the elutriator 8.

At an upper end of the elutriator 8 is a first outlet 20 connected via a further conduit 22 to, in turn, a filter 24, a second rotometer (not shown), and a 30L/min vacuum pump 26. The filter 24 is, in this embodiment, a 37mm 3 piece Millipore cassette.

Toward the upper end of the elutriator 8 is a second outlet 30, to which there is connected a further conduit 32 extending between a cowl located in the elutriator 8 and an associated air sampling pump 34 mounted on the support column 6.

An exemplary method for using the exemplary apparatus 1 described herein may be as follows:

1. Place the dry dust .sample into the rumbler 6 whilst this is in a Local Exhaust Ventilation box

(LEV box - not illustrated) with a High Efficiency Particulate Air (HEPA) vacuum cleaner operating.

2. Place the 3 steel ball bearings in the rumbler 6.

3. Fit the rumbler 6 lid in the LEV box, and secure this in place.

4. Remove rumbler 6 from the LEV box, check that this is sealed closed.

5. Fit the cowl into the elutriator 8.

Place a P3 respirator filter into the top of the elutriator 8.

Put the elutriator cap in place and tighten it at the top of the elutriator 8. . Attach the hose to the vacuum pump 26 and rotameter.

. Attach the air sampling pump 34 to the cowl.

10. Place the nimbler 6 on the base plate 2

1 1. Connect the nimbler 6 to the elutriator 8 with the tygon tubing; start the vacuum pump 26, set the flow rate to 2 L/min at the vacuum pump 26 and then check the flow rate at the rumbler 6 with the rotameter 10, it should be 2 L/min. If not, then tighten the cap and check the flow again.

12. Disconnect the rumbler 6 from the elutriator 8 and plug the openings. Start the rumbler 6 and allow it to rotate for 5 minutes, turn off.

13. Connect the rumbler 6 to the elutriator 8 with tygon hosing.

14. Start the vacuum pump 26 and allow it to operate at 2 L/min, check that the flow rate at the rumbler 6 end of the unit, it should match the 2 L/min. If not, tighten the cap on the elutriator 8 and check the flow.

15. When the above condition is met, then turn on the rumbler 6 and the vacuum pump 26 and allow it to operate at 2 L/min for 5 minutes.

16. Switch off the vacuum pump 26 and rumbler 6 and allow the dust to settle for 8 minutes. Use a stopwatch to time the settling period.

17. The air sampling pump 34 should be set to operate at 0.5 L/minute.

18. After the 8 minutes switch on the charged air sampling pump and operate it for 2 minutes, use the stop watch to time the operation of the pump.

19. Switch off the air sampling pump 34 after 2 minutes.

20. Remove the tygon tubing connecting the elutriator 8 to the rumbler 6 and plug the rumbler 6.

21. Switch on the vacuum pump 26 and open the valve and purge the chamber of dust operating the vacuum pump 26 for 2 minutes, set the vacuum pump 26 to 2 L/min before switching it off.

22. Loosen the cap of the elutriator 8.

23. With the HEPA vacuum cleaner operating clear the air at the top of the elutriator 8 and

remove the respirator filter, vacuum the front of the filter before removing the filter.

24. Use the vacuum cleaner to remove air from the top of the elutriator 8.

25. Wear gloves and remove the cowl, cap it and wet wipe the outside surface of the cowl.

An exemplary cleaning method for the apparatus may be as follows:

1. Disconnect and cap both ends of the rumbler 6 and place the rumbler 6 in the LEV box.

2. Attach the HEPA vacuum cleaner to the box and switch this on.

3. Remove the lid of the rumbler 6.

4. Collect the ball bearings and clean the ball bearings using the vacuum cleaner and wash them. Empty the dust sample and leave the vacuum cleaner running for 1 minute.

Vacuum the lid of the nimbler 6 and the rumbler 6, then wet wipe the nimbler 6 and lid. Wash the rumbler 6 and lid with water and allow this to dry.

Wet the elutriator with water, and then remove the cowl fitting in the tube.

Using a brush, scrub the elutriator tube 8.

Rinse the elutriator tube 8 with clean water twice.

Allow to dry in a clean environment. Air can be drawn through the elutriator tube 8 using the vacuum cleaner to assist drying.

A significant advantage of the apparatus according to the present invention is that it operates under negative pressure, so any dust leaks (should they arise) are drawn in and would run through one of the three filters, not forced out through positive pressure into the atmosphere (positive pressure) as in the case of the 'Coffey Rocket'.

A further advantage is that the apparatus fits into a standard "Pelican 1650 Case" and can be reassembled on site within 15 minutes, including calibration checks. Moreover, the final weight of each unit is low, so it can be lifted and carried in the boot of a normal sedan. What is more, the apparatus is reasonably robust and its operation is not overly sophisticated. All of the above makes the apparatus ideal for quick, convenient and above all, accurate on site testing.

Referring now to Figure 2, where a testing apparatus 100 according to a second exemplary embodiment is illustrated.

Whilst being portable, some manual handling issues arose with apparatus 1 (above).

Moreover the continual construction and dismantling of apparatus 1 required in order to clean parts of apparatus 1 between the testing of one sample and the next (so as to prevent cross-contamination), was found to be time consuming, and was limiting the number of samples being tested daily.

Apparatus 100 again comprises a base plate 2 upon which there is mounted a sample agitator in the form of a rumbler 4 (a dry operating ball mill, which grinds the particles while generating the dust cloud), there is a conduit 50 connecting the rumbler 4 to an elutriator 102, and a further conduit 60 connecting the elutriator 102 to an air sampling pump 34 which may also be secured to the base plate 2.

It can be seen then that the apparatus 100 has done away with the large elutriator 8 and vacuum pump 26 of apparatus 1. The elutriator 102 is an elongate tube (hereinafter elutriator tube 102) of clear plastic or metal material having an inlet 104 in one end and an outlet 106 in the distal end which is in line with the inlet 104. In this exemplary embodiment, the elutriator tube 102 is approximately 100mm long, with an internal diameter of 25mm, which is reduced down to approximately 5mm at the inlet and the outlet. Extending across the inside of the outlet end of the elutriator tube 102 is a sampling medium 1 10. This sampling medium 1 10 may be a mixed cellulose ester gridded membrane filter.

The design of this elutriator tube 102 ensures that laminar flows occur through this at the sample collection point, so that even distribution across the filter 1 10 is achieved.

Elutriator tube 102 is relatively compact and inexpensive to manufacture from plastic. As a result, an operator can take many of these elutriator tubes 102 on site.

A further advantage of this elutriator tube 102 is that it may be disposable, thereby eliminating the need for the dismantling and cleaning of a larger, non-disposable elutriator 8 of the type employed in apparatus 1.

A further advantage of making the elutriator tube 102 from a clear plastic material is that the amount of material captured by the membrane filter 1 10 can be observed, ensuring that the source of vacuum (provided by air sampling pump 34) is not shut down until sufficient material has been collected to take a reliable reading.

Apparatus 1 removes the need for filtration, purging systems and the need to access the elutriator tube 102 to collect the sampling medium.

An exemplary method for using the exemplary apparatus 100 described herein may be as follows:

1. Place the dry dust sample into the nimbler 4 inside a Local Exhaust Ventilation box (LEV box- not illustrated) with a High Efficiency Particulate Air (HEP A) vacuum cleaner operating. 2. Place the 3 steel ball bearings in the nimbler 4.

3. Fit the nimbler 4 lid in the LEV box, and secure this in place.

4. Remove nimbler 4 from the LEV box, check that the seal has no gaps.

5. Place the nimbler 4 on the base plate 2.

6. Start the nimbler 4 and allow it to rotate for selected period, turn off.

7. Switch off the nimbler 4 and allow the dust to settle

8. Connect the nimbler 4 to the tygon hosing 50, connected to the elutriator tube 102, in turn connected to the air sampling pump 34. 9. The air sampling pump 34 should be set to operate at a desired flow rate.

10. After the selected agitator period, switch on the charged air sampling pump 34 and operate it for selected sampling periods, use the stop watch to time the operation of the pump.

1 1. Switch off the air sampling pump 34 after selected duration.

12. Remove the tygon tubing connecting the nimbler and plug the nimbler. '

An exemplary cleaning method for the apparatus may be as follows:

13. Remove the nimbler 6 from the base plate 2 and place in the LEV box.

14. Attach the HEP A vacuum cleaner to the box and switch this on.

15. Remove the lid of the nimbler 6.

16. Collect the ball bearings and clean the ball bearings using the vacuum cleaner and wash them.

17. Empty the dust sample and leave the vacuum cleaner running for 1 minute.

18. Vacuum the lid of the nimbler 6 and the rumbler 6 itself, then wet wipe the nimbler 6 and lid. 19. Wash the nimbler 6 and lid with water and allow this to dry.

Apparatus 100 reduces the manual handling issues associated with apparatus 1 while also improving safety systems and issues associated with the operation of apparatus 1 and simplifying operation.

Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms pari of the common general knowledge. It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that various modifications can be made without departing from the principles of the invention. Therefore, the invention should be understood to include all such modifications in its scope.