Test apparatus and method for testing dust suppression systems

Abstract

The invention as herein described discloses a test apparatus (1) for testing dust suppression systems and a method for testing dust suppression systems using said test apparatus (1). Said test apparatus (1) comprises a housing (100) with at least two chambers (101,102) being separated from each other by a window (103) which comprises at least one transfer vent (104). Therein particle counting means (110, 120) are detachably mounted to at least one of said two chambers (101,102). Further, the first chamber (101) of said at least two chambers (101,102) comprises a door (121) and is equipped with supply means for supplying the first chamber (101) with particulate free air, and wherein the second chamber (102) of said at least two chambers (101, 102) is equipped with exit means for releasing air from the second chamber (102).

Claims

1. Test apparatus (1) for testing a dust suppression system, said test apparatus (1) comprising a housing (100) with two chambers (101,102) being separated from each other by a window (103) which comprises at least one transfer vent (104), wherein particle counting means (110,120) are detachably mounted to at least one of said two chambers (101,102), and wherein a first chamber (101) of said two chambers (101,102) comprises a door (121) and is equipped with supply means for supplying the first chamber (101) with particulate free air, and wherein the first chamber (101) is configured to receive a dust-comprising test object, wherein the dust-comprising test object is provided with the dust suppression system to be tested, and wherein a second chamber (102) of said two chambers (101,102) is equipped with exit means for releasing air from the second chamber (102); wherein the at least one transfer vent (104) is a rotating air vent (104).

2. Test apparatus (1) according to claim 1, characterized in that at least one of the two chambers (101,102) comprises air filter means.

3. Test apparatus (1) according to claim 1, characterized in that at least one of the two chambers (101,102) comprises a temperature measuring device.

4. Test apparatus (1) according to claim 1, characterized in that inside the first chamber (101) a holding device for holding a test object comprising dust is arranged.

5. Test apparatus according to claim 4, wherein said holding device is a table (5), selected from a movable table or a vibrating table, and wherein said dust comprising test object is a plate or a dish (2).

6. Test apparatus according to claim 4, wherein said holding device comprises at least one of a table (5), a tube, or a spray box or a combination of two components selected from the table (5), the tube or the spray box.

7. Test apparatus (1) according to claim 4, characterized in that the holding device comprises a rectangular spray box comprising at least one spray jet and the holding device further comprises a vibrating table coupled to a vibration sensor.

8. Test apparatus (1) according to claim 4, characterized in that the holding device is a rectangular spray box comprising at least one spray jet, or the holding device (5) is a vibrating table coupled to a vibration sensor.

9. Test apparatus (1) according to claim 1, characterized in that the particle counting means (110,120) is an optical particle counter.

10. Test apparatus according to claim 9, wherein the optical particle counter is a laser particle counter (110,120).

11. Test apparatus (1) according to claim 1, characterized in that the housing (100) is, at least partially, made of a transparent material selected from glass or a glassy polymer.

12. Test apparatus (1) according to claim 1, characterized in that the supply means for supplying the first chamber (101) with particulate free air comprise an air control valve (10) coupled to a mass flow meter (13) which is fitted into a wall of the housing (100) constituting the first chamber (101), and a hose (12) being coupled to the mass flow meter (13).

13. Test apparatus according to claim 1, wherein the first chamber (101) comprises a first filter unit (21) fit into a wall of the housing (100) constituting the first chamber (101) and wherein the second chamber (102) comprises a second filter unit (22) fit into a wall of the second chamber (102), wherein the second filter unit (22) is said exit means.

14. Test apparatus (1) according to claim 1, wherein the first chamber comprises a first temperature probe and the second chamber comprises a second temperature probe.

15. Method for testing dust suppression systems using a test apparatus (1) comprising a housing (100) with two chambers (101,102) being separated from each other by a window (103) which comprises at least one transfer vent (104), wherein particle counting means (110,120) are detachably mounted to at least one of said two chambers (101.102), and wherein a first chamber (101) of the two chambers (101,102) comprises a door (121) and is equipped with supply means for supplying the first chamber (101) with particulate free air, and wherein the first chamber (101) is configured to receive a dust-comprising test object, wherein the dust-comprising test object is provided with the dust suppression system to be tested, and wherein a second chamber (102) of said two chambers (101,102) is equipped with exit means for releasing air from the second chamber (102); the method comprising the steps of a) providing the housing (100) with the first chamber (101) and the second chamber (102) and b) placing the dust comprising test object provided with the dust suppression system and a weighed amount of dust particulates inside the first chamber (101), c) providing a particulate free air flow (A1) into the first chamber (101), thereby disturbing releasable dust particulates (4) from the dust comprising test object, and providing an airflow (A3) comprised of the particulate free air flow (A1) and air borne dust particulates (4), d) allowing the airflow (A3) to pass the transfer vent (104) in a controlled way and to enter the second chamber (102), e) activating the particle counter (120) at the second chamber (102) and quantifying dust particulates (4) in the airflow (A3), and f) based on a number of quantified particulates (4) in relation to the weighed amount of dust particulates (4), determining an efficiency of dust retention of the dust comprising test object.

16. Method according to claim 15, comprising, before performing step b), the step b′) of performing calibration of the first chamber (101) by using a first particle counter (110) at the first chamber (101) with no test object comprising dust inside, and counting particles; thus providing a particle background of the first chamber (101).

17. Method according to claim 16, wherein during performance of any of the steps b′), b) to e) punctually or continuously measuring a temperature of at least one of the two chambers (101,102).

18. Method according to claim 15, wherein airborne dust particulates (4) in the airflow (A3) or dust particulates (4) in the first chamber (102) with no test object comprising dust inside are quantified versus time.

19. Method according to claim 18, wherein the airborne dust particulates (4) in the airflow (A3) or the dust particulates (4) in the first chamber (102) are quantified over at least two particulate sizes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects and many of the attendant advantages of embodiments of the present invention will be readily appreciated and become better understood by reference to the following detailed description of preferred embodiments in connection with the accompanied drawing(s). Features that are substantially or functionally equal or similar will be referred to with the same reference sign(s).

(2) FIG. 1 shows a schematic side view of a test apparatus according to the invention with no test object in it,

(3) FIG. 2 shows the view of FIG. 1 with a test object inside,

(4) FIG. 3 shows a flow chart depicting air flows through the test apparatus

(5) FIG. 4 shows a schematic side view of a test apparatus “wet dust cabinet” according to the invention with spray box and jets,

(6) FIG. 5a shows a comparison of measurements with and without dust suppression fluid (water),

(7) FIG. 5b shows a comparison of measurements with and without dust suppression fluid (spray down suppressant).

DESCRIPTION OF PREFERRED EMBODIMENTS

(8) The test apparatus 1 as shown in FIGS. 1 and 2 shows as housing 100 a clear, transparent Poly(methyl methacrylate) (PMMA) cabinet with the first chamber 101 being separated from the second chamber 102 by the window 103 which comprises a transfer vent 104 herein designed as an adjustable rotatable vent 104. FIGS. 1 and 2 show both chambers 101,102 housing laser particle counting means 110,120.

(9) Of course, other materials than PMMA can be used for the housing. The housing even could be a wind tunnel or the like as long as the arrangement as herein described with said two chambers and the equipment is provided as disclosed.

(10) As can be seen in FIGS. 1 and 2, the first chamber 101 and the second chamber 102 each comprise a door 121,122, to allow handling of inside objects. The supply means for supplying the first chamber 101 with particulate free air comprise an air control valve 10 coupled to a mass flow meter 13 which is fitted into the left front wall of the first chamber 101. A hose 12 is coupled to the mass flow meter 13 ends in a nozzle 11.

(11) This arrangement allows the airflow A1, see FIG. 3, to be blown into the first chamber 101 under controlled conditions. The airflow A1 supplies clean air, or, respectively, dust free air.

(12) To optimize controlling of the conditions in the first and second chambers 101,102, temperature probes 41,42 are installed; one in each chamber 101,102.

(13) The arrangement of the test apparatus 1 of FIG. 1 provides the efficient filter units 21,22 in each of said chambers 101,102.

(14) FIG. 2 then shows the test apparatus 1 of FIG. 1, but inside said first chamber 101 a vibrating table 5 as test object holder is installed, and the test object, herein a test dish 2 having a coating 3 and being laden with dust particulates 4, is placed (through the door 121) onto said table 5.

(15) To perform test measurements, the first chamber 101 is now fed with dust free air (airflow A1, see FIG. 3) using the mass flow meter 13 and activating valve 10. The airflow A1 exits through a flat nozzle 11 fixed at the hose 12 which is coupled to the mass flow meter 13. Using said nozzle 11, advantageously the angle of attack of airflow A1 directed onto the test dish 2 can be varied to a suitable fixed position. During measurements, temperature probes 41,42 record the air temperature in both chambers 101,102. The mass flow meter 13 is calibrated such that the air velocity of airflow A1 can be accurately determined at the point of exit from the nozzle 11.

(16) In the absence of any test object which can release dust particulates, the cleanliness of the inside of the first chamber 101 and the second chamber 102 is confirmed through the use of the calibrated particle counter 110,120, which is placed in a fixed position in the “clean chambers 101,102”. Before any measurement the still empty chambers 101,102 are calibrated as such, in order to determine any dust background and ensure a preset cleanliness. Once background cleanliness is established, the door 121 is opened and the test dish 2 is placed on the table 5 (which can be vibrated).

(17) Measurement starts: The air is turned on (airflow A1) and the particle counter 120 is started in the second chamber 102. Air from airflow A1 blows over the test dish and particulates 4 become airborne. This particulate laden airflow A1 flows towards the window 103, becoming an airflow which separates in the airflow A3, passing the transfer vent 104 and entering the second chamber 102, and in the airflow A2, which leads the excess air into the effective dust filter unit 21 of the first chamber 101 preventing dust to pollute the environment of the test apparatus 1.

(18) Airflow A3, which flows from the side with the test dish 2 (first chamber 101) to the particle counting second chamber 102, is analysed and the release of particulates 4 is quantified by the particle counter 120 in said second chamber.

(19) In order to determine a relation of particulates 4 having become airborne and particulates 4 having been retained on the test object, it is advisable to predetermine the amount of particles by weighing said particulates 4 beforehand. Of course mixtures of different particle size ranges can be provided. Further it is possible to design the first chamber 101 as glove box or to put the whole test apparatus into a glove box.

(20) The particle counter 120 records the live particulates 4 versus time. The level of dust is herein quantified over four dust size ranges ranging from 0 to 1 μm, over 1 μm to 2.5 μm, over 2.5 μm to 5 μm and from over 5 μm to 10 μm. Of course, other ranges may be selected. Temperature is measured in the second chamber 102, too. Finally, the air in the second chamber 102 flows as airflow A4 through the second filter unit 22 and clean air exits the test apparatus 1.

(21) By measuring the build-up of particles the ability of the test coating 3 or of any test system can be quantified against time, temperature, air velocity and mechanical vibration level, a calculation can be made of the effectiveness of the test coating or treatment to a known substance to give an efficiency in percent. A combination of the listed equipment of the test apparatus combined with a data capture system and display enables to store and visualize data and display real time information on quantity and size range of airborne particulates generated.

(22) FIG. 4 shows the schematic side view of a test apparatus “wet dust cabinet” 1′ with a spray box 200 and three jets 201. Via the tubing 202, the jets 201 are connected to the fluid reservoir 203 which contains water or a fluid being a mixture of water and the dust suppression chemicals to be tested. The fluid reservoir 203 is coupled to the compressor 204, which provides the necessary pressure for the fluid to be injected into the spray box 200 via jets 201. This “wet dust cabinet” 1′ helps analysing dust suppression fluids by capturing dust. Herein, the dust suppression fluid is pumped under air pressure into the spray box 200 to the spray jet system comprised of said jets 201, the spray interacts with the dust, wets it and brings it down, so reduces the level of airborne dust reaching the particle counter 120.

(23) Tests can be made dry, without the spray (with “dry dust cabinet”), then with water (with “wet dust cabinet”), then with the dust suppression treated water.

(24) FIGS. 5a and 5b show the comparison of the area of the respective graph related to “dry, no suppressant” and “water only”, see FIG. 5a, and to “water only and 0.5% Spray-Down suppressant” of FIG. 5b. So, by comparing the graphs, the effectiveness of the fluid and thus its effectiveness in dust suppression can be determined. Comparison parameters might be peak height, peak area, location of peak and relation of peaks; particle counts versus time.

(25) So, the invention provides a laboratory and demonstration apparatus which can quantify the effectiveness of dust suppression systems using a controlled measured airflow, vibration and particle counter combination.

REFERENCE NUMERALS

(26) 1 Test apparatus 1′ Wet dust cabinet 2 Test dish 3 Coating 4 Particles 5 Table 10 Air control valve 11 Nozzle 12 Hose 13 Mass flow meter 21 First filter unit 22 Second filter unit 41 First temperature probe 42 Second temperature probe 100 Housing 101 First chamber 102 Second chamber 103 Separating window 104 Transfer vent 110 Particle counter of first chamber 120 Particle counter of second chamber 121 Door 122 Door 200 Spray box 201 Jet 202 Tube 203 Fluid Reservoir (water, dust suppression fluid) 204 Air Compressor A1 Airflow into first chamber A2 Airflow into first filter unit A3 Airflow from first chamber into second chamber A4 Airflow into second filter unit CLAIMS