GB2233462A - Aerosol fabric penetration measurement system - Google Patents
Aerosol fabric penetration measurement system Download PDFInfo
- Publication number
- GB2233462A GB2233462A GB9012759A GB9012759A GB2233462A GB 2233462 A GB2233462 A GB 2233462A GB 9012759 A GB9012759 A GB 9012759A GB 9012759 A GB9012759 A GB 9012759A GB 2233462 A GB2233462 A GB 2233462A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fabric
- air
- housing
- aerosol
- particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000004744 fabric Substances 0.000 title claims abstract description 91
- 239000000443 aerosol Substances 0.000 title claims abstract description 76
- 230000035515 penetration Effects 0.000 title claims abstract description 12
- 238000005259 measurement Methods 0.000 title claims description 6
- 239000002245 particle Substances 0.000 claims abstract description 86
- 238000007664 blowing Methods 0.000 claims description 8
- 238000003556 assay Methods 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 241000894006 Bacteria Species 0.000 description 2
- 210000002445 nipple Anatomy 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 244000063299 Bacillus subtilis Species 0.000 description 1
- 235000014469 Bacillus subtilis Nutrition 0.000 description 1
- 241000412626 Penetes Species 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000003189 isokinetic effect Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000002906 microbiologic effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
Landscapes
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
A system for determining the aerosol penetration of fabrics e.g for analyzing the protectiveness of fabrics subject to biological warfare aerosols comprises a housing 1 having a fabric 2 closing the open end thereof, means 3, 4 located opposite the fabric for drawing air from the housing, and means 8, 9, 10 for injecting clean air devoid of the aerosol into the interior of the housing at the same time and in the same quantity as the air drawn from the housing, so as to maintain the same air pressure within the housing as that outside the housing. Particle measuring means 6 is used to count the aerosol particles and/or the sizes of the particles contained in the air drawn from the housing. With the above system the particles measured are due only to factors outside the fabric and the quality of the fabric, and not due to air pressure difference between the air inside and the air outside the housing. The housing 1 is located within a chamber 13 containing the aerosol laden air, a laminar flow 21 simulating field conditions, being directed against the fabric. <IMAGE>
Description
Aerosol Fabric Penetration Heasuremen: System
This invention relates ts a system for determining the aerosol penet=ation of fabrics, and is partlcularly useful for measuring penetration or biological war'are aerosols into fabrics which may be used for protective clothing, or other coverings.
It is important to be able to characterize fabrics as to the degree of protectiveness which they can provide when formed into overgarments for persons who made be subjected to biological warfare aerosols. who Such aerosols can include for example bacteria or clumps of bacteria, chemical molecules or clumps of chemical molecules, etc. In order to determine the protectiveness of fabrics a microbiologial assay technique has been used.However this technique is slow, and therefore limits the number of experiments that can be done within a reasonable time. Muc manual experimental manipulation dnd subsequent calculation is required before results can be obtained using the assay technique. The time.lag from start to completion of a test usually takes as long as three to four days, and highly trained technical personnel are required to obtain reproducible results.
The present invention is a fabric test apparatus which can provide results in a time span of minutes, rather than days. The experimental determination has been found to be replicated easily, and without using highly trained technical personnel.
The results are provided as data signals in formats useful by standard computer apparatus. Accordingly the present invention can be used to characterize a wide variety of fabrics in a relatively short period of time in the presence of diverse aerosol environments.
It has been found that results obtained by the present invention are consistently reproducible with a low rance of error, and by the use of the present invention graphs =In be procucey cr use by planners so that a fabric can be chosen easily and quickly using the characterizing graphs for a particular biological warfare environment. The use of the present invention is thus a considerable improvement over the previous assay method of characterizing fabrics for the above-noted application.
In accordance with a preferred embodiment, an aerosol fabric penetration measurement system is comprised of a housing having one open end, the fabric closing the open end. A structure located opposite the fabric associated with the housing draws air from the housing. Clean air devoid of the aerosol is injected into the interior of the housing at the same time and in the same quantity as the air drawn from the housing, so as to maintain the same air pressure within the housing as that outside the housing. A particle measuring means is used to count the aerosol particles and/or the sizes of the particles contained in the air drawn from the housing. With the above structure the particles measured are due only to factors outside the fabric and the quality of the fabric, and not due to air pressure difference between the air inside and the air outside the housing.
In accordance with another embodiment, air containing aerosol particles is blown at the outside surface of the fabric. Aerosol contained in air which is not blown is collected, and the particles of aerosol in that air which is not blown are compared with the particles in the air within the housing resulting from the blown air. The particle counting apparatus provides signals which are stored and manipulated by a computer, and which provides output signals and/or display data which can graphically display the aerosol penetration of the fabric as compared to the aerosol density and particle size outside the fabric.
A better understanding of the invention will be obtained by reference to the detailed description below in conjunction with the following drawings, in which:
Figure 1 is a schematic diagram of the preferred embodiment of the invention,
Figure 2 is a perspective of the funnel shaped housing and fabric structure,
Figure 3 is a perspective of the front view of an embodiment of the invention,
Figure 4 is a perspective of an end view of the invention, and
Figure 5 is a resulting graph of wind speed vs number of particles.
Turning to Figure 1, a housing 1 which is preferably funnel shaped has an open inlet end over which is located a layer of the fabric 2 to be tested. Preferably the fabric is clamped around the periphery of the housing, in order to close the inlet.
A tube 3 leads from the exit end 4 of the housing to an inlet 5 of a particle measuring instrument 6 which also filters the air. Filtered air egressing from the particle measuring instrument 6 is led from an outlet 7 via a tube 8 to an air injecting tube 9 which is located within the housing 1, just inwardly of the fabric 2. The tube 9 can be a rigid tube welded, soldered or bonded across the housing 1, and contains a hole 10 or series of holes communicating with the interior of the housing.
The particle measuring instrument is preferably a light scattering aerosol particle sizer such as CLIMET Model CI 208, which is available from
Climet Instrument Co., Redlands, California. An instrument such as this provides a count of the number of particles of particular sizes, and provides pulse height signals at an output line +11, the number of particles in each of selected size groups being indicated in the various output channels of the instrument. It also filters and provides clean air at its outlet which is equal to the amount of air entering at its inlet (being the same air, but having been filtered).
In operation, the particle measuring instrument draws air via the outlet tube 3 and the outlet 4 from the interior of chamber 1, and provides an equivalent amount of clean air via outlet 7, tube 8, tube 9, and hole 10 to the interior of the chamber. The result of the air pressure compensation by the equal volume of clean air is that the inside of the chamber suffers no change in air pressure with respect to the air outside the chamber. Thus the only possible place where air can enter the chamber is through the fabric 2.
The housing 1 is located in an atmosphere of air containing aerosol particles. A laminar flow of this air is directed against the outside of the fabric 2, e.g. in the direction of arrow 12. Thus the fabric 2 is subjected to conditions similar to what would be experienced in the field, that is, that the pressure for aerosol particles to pass through the fabric is caused by an external wind, rather than a differential in pressure between the inside and outside of the fabric caused by a reduction in pressure behind the fabric. The particle measuring instrument measures the aerosol particles having passed through fabric 2 as a result, replacing the air containing the measured aerosol particles with clean air. The result is that only new aerosol particles passing through the fabric 2 becomes measured.
With a computer interpreting the signal on output bus 11, an on-line apparatus is thus provided which provides an indication of the number of aerosol particles within each size group supporting a channel in the particle measuring apparatus which has passed through the fabric. It is preferred that a measurement should be made following predetermined increments of time, such as 85 seconds, in order to allow sufficient aerosol particles to pass through the fabric to provide a meaningful measurement.
Alternatively a measurement can be made each time a predetermined count of particles has been measured.
It is preferred that the housing 1 should be located within a chamber 13, for containing the aerosol laden air. This chamber both protects the user and facilitates the formation of a homogeneous medium to measure. The chamber can be, for example, a sealed room or a sealed chamber which is a fraction of the size of a room. Aerosol injection apparatus which creates the aerosol laden air within the room is not part of the present invention.
In accordance with another embodiment, a second particle measuring instrument 14 should be used to determine the aerosol content of the chamber. The particle measuring instrument 14 should be identical to that of instrument 6. Its inlet 15 is connected via a tube 16 to the interior of the chamber 13, but with the inlet to the tube 16 at a position which is remote from the air flow of the simulated wind against fabric 2. The purpose of the spacing of the inlet of the tube 16 from the wind is to avoid isokinetic sampling errors. The outlet 17 of the second particle measuring instrument 14 exhausts clean air outside the chamber 13. The amount of sampled air taken via tube 16 is so small in comparison to the volume of the chamber 13 that there is substantially no decrease in pressure within the chamber 13 due to its removal.
However if the chamber 13 is made so small that the air removed is deemed to be significant, the exhaust air from tube 17 can be reintroduced into the chamber 13 at position remote from the inlet of tube 16 so as not to affect the particle density or homogeneity in the region of the inlet to the tube 16.
Particle measuring instrument 14 provides on its output bus 18 signals in its particle size channels which correspond to the number of particles for various particle size groups within the chamber 13, exterior to the housing 1.
The signals on output buses 11 and 18 are applied to a multichannel monitor 19, such as Model
CI 210 which is available from the afoxenoted Climet
Instrument Co. The output of multichannel monitor 19 where it is multiplexed and is applied via an RS 232 bus to a microcomputer 20 which is preferably connected in a well known manner to a printer 21.
In a laboratory test, the concentration of the aerosol was controlled by the particle measuring instrument 14 providing concentration and particle size data through multichannel monitor 19 to microcomputer 20, which in turn controlled an aerosol supply. A suspension of Bacillus subtilis spores was used to produce the test aerosol but virtually any other solid particles could be substituted.
The flow rates of both of the particle measuring instruments was set to 7.08 litres per minute. The sensitivities of the two instruments were balanced to give similar readings to sample the aerosol source and both instrument were calibrated.
Once calibrated, the fabric was clamped over the open end of the housing 1. The output signal of particle measuring instrument 14 provided an indication of the number of particles per size increment within the aerosol chamber 13, while the output signal of particle measuring instrument 6 provided an indication of the number of particles per size increment that had passed through fabric 2, which is caused by the simulated wind directing the aerosol laden air against the outside of fabric 2.
The ratio of the output signal for each channel from particle measuring instruments 6 to that from particle measuring instrument 14 provides an indication of the quality of the fabric; the higher the ratio the higher the quality of the fabric, for a particular particle size. In the labratory model, 16 channels of particle size and number data were provided, and were calculated and multiplexed by multichannel monitor 19 on an RS 232 bus to microcomputer 20.
A sampling time of 85 seconds was chosen to be the most efficient compromise sampling interval.
At the end of each 85 second period, the multichannel monitor performed calculations of particle numbers for 16 size channels from pulse height signals transmitted simultaneously from particle measuring instruments 6 and 14. The raw data stream was transmitted serially on the RS 232 bus in ASCII characters. These ASCII characters can be used by most common microcomputers in common use today.
A hot wire anemometer 22 can be located immediately outside the fabric 2, facing into the wind, in order to receive the force of the simulated wind against the fabric 2. The output end of the anemometer is connected to a translator 23 which provides a signal to multichannel monitor 19, which multiplexes it with the other data on the RS 232 bus for reception by microcomputer 20. A correlation of the wind speed with the number of particles in each size increment passing through fabric 2 for a given density of particles within each particle increment can thus be determined, and can be displayed by microcomputer 20 and printed in hard copy on printer 21 in a well known manner.
Figure 2 is an exploded perspective of the housing portion of the invention. The preferably funnel shaped housing 1 contains an air injecting tube 9 disposed along a diameter and just inwardly of its mouth. An end of the tube extends through the housing to provide a clean air inlet nipple 24 for connection to a clean air supply hose. The tube 9 also contains a hole (not shown) preferably facing rearwardly on the axis of the housing 1.
A flexible tube 3 terminating in a hose adaptor 25 is pre3s fitted over the outlet end 4 of housing 1.
A layer or several layers of fabric 2 to be tested are disposed over the inlet end of the housing 1 and are clamped by means of a large hose clamp 26.
In the above structure, the only place from which air from the exterior of the housing 1 can enter to within the housing is through the fabric 2, assuming that the tube 3 is connected to particle measuring instrument 6, which exerts a suction force via tube 3 and nipple 24 is connected to a clean air supply. The same volume of air which is pulled via tube 3 is replaced via the air injecting tube 9. As a result the air pressure within housing 1 remains constant, and the same as that outside the housing 1.
It is preferred that the housing 1 should be located within a wind tunnel in order to ensure that the wind hitting the fabric should be laminar. The wind tunnel is shown in Figures 3 and 4, Figure 3 showing the-front and Figure 4 showing the rear thereof. The wind tunnel is formed of a cylinder 27, preferably made of stainless steel in order that contaminants should not pass from the inside walls of the cylinder to the air within. At the inlet end of the cylinder a fan 28 is located for blowing aerosol laden air from the outside of the tunnel through the cylinder 27, in a laminar flow. A hole 29 is provided in the cylinder to accommodate a hot wire anemometer such as anemometer 22 discussed with reference to
Figure 1.
In Figure 4 the rear of the tunnel is
shown. The housing is disposed within the tunnel with
its large end facing the fan, the fan being located at the opposite end 30. The exit end 4 of the housing is centrally supported by means of fin shaped arms 31, with tube 3 passing outwardly along the axis of the cylinder-housing combination.
It should be noted that rather than using a clamp 26 as shown in Figure 2 to hold the fabric in place, another structure can be a ring on which the arms 31 are fixed. The ring slips around the housing and retains the fabric in position, while retaining the housing in position coaxially with the cylinder 27.
Preferably the diameter of the wide end of the housing is no more than one half the diameter of the cylinder, in order to allow air to pass around it and maintain laminar flow.
Figure 5 is a graph showing the results of an experiment using the present invention, being applied wind speed vs number of particles having penetrated through the fabric, for a particular fabric. In this experiment, 10 minutes sampling time was chosen for each wind speed condition before a change was initiated. Thus the 10 minute exposures in each of 0, 1.8, 3.7, 5.5 and 7.3 kph wind speed conditions provided a total run time of 50 minutes.
It was determined by using the above-described invention that the particle numbers were quite constant for each channel with respect to time, given a steady aerosol concentration generated and injected into the aerosol chamber. The aerosol, while not entirely monodispersed, contained identifiable particle sizes attributed to various components, such as the actual spore size used, as well as spore clumps or particles derived from a dried suspension fluid (mostly buffer material) used.
In general, it has been found that the present invention provides consistent and reproducible results, which correlate well with the values determined using microbiologic assay. As such it facilitates easy and rapid characterization of various fabrics. As a result of plotting the characteristics with respect to the particle size, particle density and wind, a user could deduce and optimize the level of protection required to satisfy predetermined safety requirements. The present invention allows this to be facilitated quickly and repeatedly for the first time.
A person understanding this invention may now conceive of various other embodiments satisfying the principles described herein. All are considered to be within the scope of the invention defined in the claims appended hereto.
Claims (9)
1. A aerosol fabric penetration measurement system comprising:
(a) a housing having one open end,
(b) means for closing said end by a layer of the fabric,
(c) means located opposite the fabric for drawing air from the housing,
(d) means for injecting clean air devoid of said aerosol into the housing at the same time and in the same quantity as the air drawn from the housing, so as to maintain the same pressure within the housing as outside the housing, and
(e) first means for measuring particles contained in air drawn from the housing,
whereby the particles measured are due to the quality of the fabric.
2. A system as defined in claim 1 in which the air injecting means is adapted to inject said clean air immediately behind the fabric within the housing.
3. A system as defined in claim 2 in which the housing is funnel shaped having a wide mouth and a narrow outlet, the fabric being stretched and held over the entire mouth of the funnel shaped housing, and the means for drawing air is comprised of a hose fitted over the narrow outlet of the funnel shaped housing.
4. A system as defined in claim 3 in which the means for measuring particles is a particle counter.
5. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric.
6. A system as defined in claim 1, 3 or 4 in which the housing is contained within a wind tunnel, with the outside surface of the fabric facing upwind, for providing laminar flow of aerosol-containing air against the outside surface of the fabric.
7. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric, means for collecting aerosol containing air which is not blown, second means for measuring the particles of aerosols in said air which is not blown, means for comparing the particles in said air which is not blown with the particles in the air drawn from the housing so as to obtain an index of aerosol fabric penetration as compared to the aerosol content of the air external to the fabric.
8. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric, means for collecting aerosol containing air which is not blown, second means for measuring the particles of aerosols in said air which is not blown, means for comparing the particles in said air which is not blown with the particles in the air drawn from the housing so as to obtain an index of aerosol fabric penetration as compared to the aerosol content of the air external to the fabric, the housing and means for collecting aerosol containing air which is not blown
5. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric.
6. A system as defined in claim 1, 3 or 4 in which the housing is contained within a wind tunnel, with the outside surface of the fabric facing upwind, for providing laminar flow of aerosol-containing air against the outside surface of the fabric.
7. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric, means for collecting aerosol containing air which is not blown, second means for measuring the particles of aerosols in said air which is not blown, means for comparing the particles in said air which is not blown with the particles in the air drawn from the housing so as to obtain an index of aerosol fabric penetration as compared to the aerosol content of the air external to the fabric.
8. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric, means for collecting aerosol containing air which is not blown, second means for measuring the particles of aerosols in said air which is not blown, means for comparing the particles in said air which is not blown with the particles in the air drawn from the housing so as to obtain an index of aerosol fabric penetration as compared to the aerosol content of the air external to the fabric, the housing and means for collecting aerosol containing air which is not blown being located within a chamber for enclosing and maintaining a predetermined aerosol density in said air.
9. A system as defined in claim 1, 3 or 4 further including means external to the fabric for blowing aerosol containing air against the outside of the fabric, means for collecting aerosol containing air which is not blown, second means for measuring the particles of aerosols in-said air which is not blown1 means for comparing the particles in said air which is not blown with the particles in the air drawn from the housing so as to obtain an index of aerosol fabric penetration as compared to the aerosol content of the air external to the fabric, the comparing means being comprised of a multichannel monitor for receiving signals from the first and second measuring means, and a computer for receiving and storing data carried by said signals and for providing an output display of either or both of particle quantity and particle size within the housing against velocity of air blown against the outside surface of the fabric and/or particle quantity or particle size outside the housing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA603684 | 1989-06-22 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9012759D0 GB9012759D0 (en) | 1990-08-01 |
| GB2233462A true GB2233462A (en) | 1991-01-09 |
| GB2233462B GB2233462B (en) | 1993-01-06 |
Family
ID=4140246
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9012759A Expired - Fee Related GB2233462B (en) | 1989-06-22 | 1990-06-08 | Aerosol fabric penetration measurement system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2233462B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4215783A1 (en) * | 1992-05-13 | 1993-11-18 | Jagenberg Ag | Method and device for determining the filtration effect of filters for the filtration of air, gases or liquids on filling and closing machines or the like, in particular in the treatment of sterile air |
| GB2330914A (en) * | 1997-04-17 | 1999-05-05 | Samsung Electronics Co Ltd | Testing the filtration efficiency of cloth materials |
| CN105973784A (en) * | 2016-06-03 | 2016-09-28 | 中国安全生产科学研究院 | Solid particle protective clothing detection experiment chamber |
| US20200371015A1 (en) * | 2013-03-15 | 2020-11-26 | Particles Plus, Inc. | Remote access operation of particle counter devices |
| US11913869B2 (en) | 2013-03-15 | 2024-02-27 | Particles Plus, Inc. | Personal air quality monitoring system |
| US11988591B2 (en) | 2020-07-01 | 2024-05-21 | Particles Plus, Inc. | Modular optical particle counter sensor and apparatus |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117969379B (en) * | 2024-03-28 | 2024-06-04 | 四川巴蜀国草麻业有限公司 | Textile fabric air permeability detection device and test method |
-
1990
- 1990-06-08 GB GB9012759A patent/GB2233462B/en not_active Expired - Fee Related
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4215783A1 (en) * | 1992-05-13 | 1993-11-18 | Jagenberg Ag | Method and device for determining the filtration effect of filters for the filtration of air, gases or liquids on filling and closing machines or the like, in particular in the treatment of sterile air |
| GB2330914A (en) * | 1997-04-17 | 1999-05-05 | Samsung Electronics Co Ltd | Testing the filtration efficiency of cloth materials |
| US5939617A (en) * | 1997-04-17 | 1999-08-17 | Samsung Electronics Co., Ltd. | Method and apparatus for testing the filtration efficiency of cloth materials intended for use in a clean room environment |
| GB2330914B (en) * | 1997-04-17 | 2001-07-18 | Samsung Electronics Co Ltd | Method and apparatus for testing the filtration efficiency of cloth materials intended for use in a clean room environment |
| DE19816489B4 (en) * | 1997-04-17 | 2004-09-16 | Samsung Electronics Co., Ltd., Suwon | Method and device for testing the filter efficiency of fabrics intended for use in a clean room environment |
| US20200371015A1 (en) * | 2013-03-15 | 2020-11-26 | Particles Plus, Inc. | Remote access operation of particle counter devices |
| US11913869B2 (en) | 2013-03-15 | 2024-02-27 | Particles Plus, Inc. | Personal air quality monitoring system |
| US20210025806A1 (en) * | 2014-04-30 | 2021-01-28 | Particles Plus, Inc. | Power management for optical particle counters |
| US20210025807A1 (en) * | 2014-04-30 | 2021-01-28 | Particles Plus, Inc. | Instrument networking for optical particle counters |
| US20210025805A1 (en) * | 2014-04-30 | 2021-01-28 | Particles Plus, Inc. | Particle counter with advanced features |
| US11835443B2 (en) * | 2014-04-30 | 2023-12-05 | Particles Plus, Inc. | Real time monitoring of particle count data |
| US11841313B2 (en) * | 2014-04-30 | 2023-12-12 | Particles Plus, Inc. | Power management for optical particle counters |
| US11846581B2 (en) * | 2014-04-30 | 2023-12-19 | Particles Plus, Inc. | Instrument networking for optical particle counters |
| CN105973784A (en) * | 2016-06-03 | 2016-09-28 | 中国安全生产科学研究院 | Solid particle protective clothing detection experiment chamber |
| US11988591B2 (en) | 2020-07-01 | 2024-05-21 | Particles Plus, Inc. | Modular optical particle counter sensor and apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9012759D0 (en) | 1990-08-01 |
| GB2233462B (en) | 1993-01-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940608 |