WO1996009527A1

WO1996009527A1 - A dust sampling equipment

Info

Publication number: WO1996009527A1
Application number: PCT/DK1995/000372
Authority: WO
Inventors: Peter S. Vinzents
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-23
Filing date: 1995-09-18
Publication date: 1996-03-28
Anticipated expiration: 1997-03-23
Also published as: DK172219B1; DK109294A; AU3470595A

Abstract

A light dust sampling equipment (1) intended to receive airborne dust from a selected environment. The equipment shall be carried at the breast of a person, and it works according to the principle of passive dust collection, that means collection of dust on a reception surface. The dust is deposited on three adhesive and transparent surfaces (3) which face forward, upside and down. Furthermore, the equipment includes a covered reference surface (2b). The airbone dust will deposit on the reception surfaces (3) by turbulent diffusion and gravitation forces. The collected dust on the three surfaces can be measured by known measuring equipment which by screening of the sampling plates can measure the amount of dust deposited. Hereafter the measuring results from the sampling plates (3) can be added and thereby a very precise measuring result can be obtained. It can be directly compared to measuring results obtained from far more expensive and more complicated equipement measuring dust according to the principle of active dust sampling.

Description

A dust sampling equipment.

The present invention relates to a dust sampling equip¬ ment which can be used to collect airborne dust. In connection with an investigation of work environment dustsamples can be collected in preparation for measuring the quantity of dust which is to be found in the air in terms of dustmass per cubic meter of air.

These dust measurements are made to determine whether an environment/work environment is unhealthy, and based on the results from these measurements precautions can be taken, e.g. by reducing dust from specific dust sources.

Different kinds of equipment are developed to measure the quantity of dust. To get realistic measurements for deter i- ning how large quantities of dust a person will inhale in a certain environment the measuring equipment is place on the person or persons who frequent the environment in which the dust measuring are to be made. The dust measurements, which are done by so called active sampling, are made with equip- ment which by means of a pump sucks in the dust into a dust collector. It concerns a rather advanced equipment which is able to maintain a certain flow to the matching dust collec¬ tor so that the dust absorbed is a function of time and therefore it takes place according to a linear scale. Typi- cally the device is placed at the person's waistline. In con¬ nection with this the air intake to the measuring equipment can be placed at the person's collar bone.

This means that a tube from the device is connected with the air intake. Subsequent measurement of the quantity of dust takes pla¬ ce by weighing the dust which stick to the dust collector. It is very small quantities which are to be weighed. Often it is less than a milligramme and therefore heavy demands are made to the accuracy of measurement of the weighing equipment. Du- ring the years the generally smaller quantities allowed in the environment, and which are measured by weighing dust sam¬ ples, have come in conflict with the margin which recognized weighing equipment works with. Therefore, the precision of these measurements will be subject to uncertainty of varying size depending on the quantity weighed. Add to this that th weighing process is time consuming and difficult. Furthermo re, the dust collection equipment is expensive and uncomfor table to wear for the test person. The purpose of the present invention is to provide a ch ap dust collection equipment which can be carried and opera ted easily and where measurement of the dust samples can be carried out easily and quickly.

According to this invention this has been achieved with light, portable equipment primarily for persons and intende to collect airborne dust for analysis in a well known analy sis device, e.g. to determination of the dust quantity sur¬ rounding a person in an environment. The equipment is creat so that it can maintain one or several test samples with an adhesive, transparent test reception media and furthermore it includes devices which make it possible to attach the e- quiproent to a person.

With the present invention it has been found that relia ble and precise measurements can be obtained by using a qui simple equipment.

As the equipment is easy to use and relatively cheap co pared to known equipment it has opened up the prospect for making much more extensive dust measurements than before. These measurement can involve several persons in many diff rent industries in which dust measuring are found to be rel vant.

As both equipment and measuring trencher moreover take little space it can easily be distributed to a larger numb of users as an ordinary postal matter. To the invention the principle of passive collection is used.

That means collection of dust on a reception surface. dust will stick to the reception surface or surfaces due t turbulent diffusion and/or gravitation forces. Through the invention it has been found that to obtain high accuracy of measurement three dust reception surfaces must be found on the equipment: a surface facing forward, surface facing up, a surface facing down and finally a bli surface which function will be described later. The invention is primarily intended for collection of dust samples to additional analysis which can determine the amount of dust in the air at the place examined, and to a mi¬ nor degree determine the amounts of different kinds of par- ticle sizes even though the tests also will provide an option to do this.

Furthermore, the equipment can be used for bacteriologi¬ cal sampling if necessary with another kind of basic material at the test surface. The invention is explained more explicitly in the fol¬ lowing with reference to the drawings at which

Fig. 1 is a stereoscopic picture of the dust samp¬ ling equipment according to the invention.

Fig. 2 is a stereoscopic picture of a sampling tren- cher.

Fig. 3 is a stereoscopic picture of the equipment placed on a person.

Fig. 4 is a dust sampling equipment differently de¬ signed according to the invention. Fig. 5 is a stereoscopic picture of a sampling tren¬ cher designed differently and

Fig. 6 is a stereoscopic picture of the equipment placed on a person by means of a strap.

Fig. 1 shows a dust sampling equipment which includes a vertical plate divided into an upper trencher holder la and a lower trencher holder Id. On Id is placed a horizontal tren¬ cher holder lb which is designed to carry two test trenchers 2 - one at the top side and one at the underside. The plate lb is at the plate la fixed in an angle lb', and hinged in the direction stated as A around an axis lc in the plate la so that it can be opened and turned against the vertical pla¬ te la. This to make the equipment more compact when it is not used. Springs placed behind the vertical plate la, Id and consisting of a strainless steel plate 1' contribute together with the gravitational effect to that the plate lb by lb' can be secured in the rake out position as steel plate 1' is pressed against surface le which will lie above the axis of rotation lc, and due to this provide resistance if the plate la is influenced in direction A. The three plates la, lb and Id include tracks 5 intended to receive test trenchers 2 which are inserted in those tracks 5.

Fig. 2 shows such a test trencher 2; it can e.g. be mad of cardboard. The test trencher consists of two lateral edg which rake out 5a, and which fit into the tracks 5 at the dust sampling equipment 1. The edges 5a also include a lock indentation in the end 2c and against the edge it is slight bended to make the installation easier. A hole 2a going through the test trencher 2 has been made and it is covered by a test plate 3 consisting of a transparent an adhesive foil. The adhesive surface on the foil 3 turns upside. The foil can e.g. be quadratic and let into the back side of th test trencher 2, so that the back side of the foil is not scratched when it is inserted in the tracks 5. The foil can also be let in between two layers in the trencher.

According to fig. 1 the lowest trencher holder Id is in tended to hold the so-called blind foil 2b which must be ke covered. This blind foil will be described more thoroughly later on. When the test trenchers 2 are let into the dust samplin equipment 1 they are secured by the above mentioned indenta tions 2a, which are put in gear with the corresponding lock in the equipment 1 (not shown) . To protect the three adhesi and detached test surfaces 3 against contact thin metal straps 4 have been placed above these. The metal straps 4 i placed at the equipment l.

The metal straps 4 have no influence on the amount of dust which can be deposited at the test surfaces 3.

Fig. 3 shows how the equipment 1 can be placed at a per son 6. The equipment can be attached to the person in sever ways, e.g. with a safety pin placed on the back side of the plates la and Id and hooked to the person's clothes or for the purpose placed at a porter's braces as shown in fig. 6. This brace consists of a neck strap 7, which through a midd piece is connected with a lower breast strap 8. The breast strap 8 can e.g. be hold tight by "limpet tape". The dust collector 1 can be secured to the middle piece with "limpet tape" and therefore the brace will be easy to remove. In the example the equipment 1 is placed on the middle of the breast of a person 6 , but it can be placed elsewhere on the breast as the equipment 1 is preferably placed as close to the person's mouth as possible to secure that the person can move comfortably.

Fig. 4 shows an alternative design where there, in con¬ nection with the trenchers 2, are used two protection straps 4. The protection straps 4 make it possible to place a cover 9. When the dust sampling is ended it can be pushed down on the test surface 3, however, without touching this surface so that the test surface is not exposed to more dust, and so that the inside of the cover can be wedged around the side surfaces on that part which rake out lb. This principal can be used in connection with all three trenchers 2. Fig. 5 shows an alternative design for a test trencher e.g. made of thin cardboard and consisting of two sections 2 and 2d, which can be folded up as a plane surface shown as in C where the position of the test trencher can be exposed to dust, or folded up as shown in B where the position of the trencher's dust collector surface 3 is protected against further dust. The two surfaces can be hold together by adhe¬ sive fixing solutions.

When the two sections 2 and 2d are folded up two out ra¬ king side edges 5a will appear as section 2d is a little wider than section 2.

When having finished the collection of dust trencher 2 can be taken out of the track 5 and section 2d will be placed in front of the test surface 3. Here after the trencher can be let into the track 5 again. In this position the reception surface of the test trencher 3 will not be exposed to dust. The equipment is intended to collect dust according to the passive method and by ordinary sedimentation on the test trenchers. According to this the largest concentrations of dust will therefore be collected on the test trencher 2 tur- ning upside at the trencher holder lb. But a part of the dust will be collected on the other two trenchers due to turbulent diffusion.

Precise measuring results can be obtained from collection of dust on the three surfaces with the orientations: up, down and forward. These results correspond in all essentials wit measurements performed with much more expensive and complic ted equipment.

The measurements can directly be spotchecked by usual a tive measuring equipment.

Measurements of the dust amount on the trenchers are do with known equipment which through screening of the trenche can measure the amount of dust according to the principle o the more dust, the less light will come through. The same e quipment is also used for determining what level of referen the trenchers have before they are used. The level of refe¬ rence is an indication for the amount of light coming throu the foil of the trencher or the same as no dust on the foil This reference value can be related to the reference number given to the test trencher.

The blind foil 2b constitutes, in relation to the meas rements, also a reference to be understand as that the foil is not exposed to dust since the front of the trencher is dust proof. Therefore, the trencher 2b only serves as reference ac¬ cording to other mechanical exposures which do not concern the dust depositing, and which have influence on the amount of light coming through the foil. This is due to the fact that when measuring the other three test trenchers special attention must be paid to a possible light penetration through the film 3 on the reference trencher 2b. Through me suring the three other test trenchers the changed light pen tration through the reference foil can be taken into ac¬ count, so that in defiance of mechanical exposures precise dust measuring can be made.

Claims

PATENT CLAIMS

1. Portable equipment (l) primarily for persons (6) and intended for reception of airborne dust, which will be analy- zed with well known analyzing equipment, among other things to determine the amount of dust surrounding a person in an environment c h a r a c t e r i z e d by the equipment being design to maintain one or several renewable test trenchers (2, 2b) with an adhesive transparent sample reception media (3) and furthermore, it includes details which make it possi¬ ble to secure the equipment to a person (6) .

2. Equipment according to claim l c h a r a c t e r i- z e d by the fact that it includes at least one reception surface (3) facing upside and a reference surface 2b.

3. Equipment according to claim 2 c h a r a c t e r i- z e d by the fact that it includes a reception surface facing outwards (la-2) .

4. Equipment according to claim 3 c h a r a c t e r i- z e d by the fact that it includes a reception surface (3) which faces down.

5. Equipment according to claim 2 c h a r a c t e r i- z e d by the fact that the plate (lb) , on which the upturned trencher (2) is placed, can be folded against the vertical surface of the equipment.

6. Equipment according to claim S c h a r a c t e r i- z e d by the fact that the plate (lb), by means of springs, can be maintained in the out raking position.

7. Equipment according to claim l c h a r a c t e r i- z e d by the fact that the reception surface (3) is covered (4) so that contact is made impossible when the trenchers (2) are let into the equipment (1) .

8. Equipment according to every of the above mention claims is c h a r a c t e r i z e d by the fact that the c centration of dust on the foil can be measured with known equipment.

9. Equipment according to claims 1 or 8 is c h a r a t e r i z e d y the fact that the trenchers (2) is design to be let into the measure equipment.