air pollution particulate sensor package

[Phil Hobbs]

On 6/30/2014 7:57 PM, Bill Sloman wrote:

On Tuesday, 1 July 2014 06:58:53 UTC+10, jurb...@gmail.com wrote:
Another thing is the wavelength of light you use in the detector.
If you define the subject as particulate matter that is VISIBLE,
that is one thing. you could use UV or IR.

the main question here is - what results do you want ? Exactly.

http://en.wikipedia.org/wiki/Light_scattering

Rayleigh scattering is intensely wavelength dependent - to the sixth
power of the particle diameter, and inversely proportional to the
fourth power of wavelength.

It would be fun to use a bunch of light sources to measure scattering
at a number of different wavelengths, and deconvolute the results to
say something about the concentrations and sizes of the different
particles doing the scattering.

You'd need Phil Hobbs to make it work ...

Back in my mis-spent youth (or maybe early middle age) I did a lot of
particle counting work. Not exactly that kind, but particle mapping in
6 dimensions (x, y, z, radial velocity, size, and time), and
collaborated a bit with some colleagues who were doing composition
sorting for particles in fluids, using the complex refractive index of
the particle to sort out bubbles, metals, nonmetals, and carbon.

At the moment I'm doing some higher speed stuff of the same sort, but
it's kind of slow going because I don't have the mechanical design and
fabrication facilities I really need for this.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Steve Wilson]

Phil Hobbs <hobbs@electrooptical.net> wrote:

AFAIK size measurement is always done by thresholding the pulse
heights.
The scattered light power goes as the sixth power of the particle
radius. (I've recently reverse-engineered several such units for two
court cases, and they all worked that way.)

Cheers

Phil Hobbs

Thanks. I was working from some description I found online, but that
makes a lot more sense. It is far easier to discriminate pulse amplitudes
than pulse widths.

I wonder if the scattered light power flattens out above some radius? For
example, if the particle size is above 2.5 microns, does the scattering
change? For example, Raleigh scattering is effective for particles much
smaller than the wavelength of the light. I believe it goes as the fourth
power of wavelength:

http://en.wikipedia.org/wiki/Rayleigh_scattering

Other approximations are used for larger particles:

http://en.wikipedia.org/wiki/Light_scattering_by_particles

It's hard to tell which approach would be best suited for typical air
quality measurements, such as mold spores and dust particles.

 

[Steve Wilson]

Phil Hobbs <hobbs@electrooptical.net> wrote:

On 6/30/2014 9:14 PM, Steve Wilson wrote:
Phil Hobbs <hobbs@electrooptical.net> wrote:

I wonder if the scattered light power flattens out above some radius?
For example, if the particle size is above 2.5 microns, does the
scattering change? For example, Raleigh scattering is effective for
particles much smaller than the wavelength of the light. I believe it
goes as the fourth power of wavelength:

http://en.wikipedia.org/wiki/Rayleigh_scattering

Yes. When the particles are big enough to be really opaque, they start
looking like geometric obstacles, so that the scattered light goes like
the intercepted area.

A fine point is that as the particles get larger, the light scatters
into a smaller and smaller range of angles around the incident k
vector.

It's hard to tell which approach would be best suited for typical air
quality measurements, such as mold spores and dust particles.

Dark field light scatter, where the laser beam, air flow, and receive
path are mutually perpendicular is good medicine. Being 90 degrees off
axis reduces the dynamic range, because larger particles, which scatter
a great deal more light, scatter most of it in the forward direction.

Interferometric systems, which are sensitive to amplitude rather than
intensity, don't suffer as badly from this. (Power goes as amplitude
squared.)

Cheers

Phil Hobbs

Boy, this sure got complicated very quick! So many issues on scattering
angles, changes with particle size, orientation, intercepted area, etc.

It's difficult to figure out what the system is actually measuring. Of
course, I understand this is one of your specialties, and you really did
some marvellous work at IBM on measuring particles in the presence of
huge interference.

And thanks for the note on interferometric measurements. That's another
area I need to look at.

Very interesting thread. Thanks. I will now be a lot more sceptical when
I see some marketing hype on a new particle instrument.

 

[Jeff Liebermann]

On Tue, 01 Jul 2014 00:24:21 GMT, Steve Wilson <none@nospam.com>
wrote:

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg

I could not find a user manual for your Nikken. If you have a pdf and can
spare the time, could you upload it to your web site?

Sure. I'll scan it later tonite.

This is a very interesting way to use a particle counter. I have some
questions:

How does the Nikken operate?

My guess(tm) is by optical scattering. The light show is inside the
black box with the air hose intake. See photos below. I didn't take
apart the box, but with 4 wires going into the box, it's a likely
guess.

>Is there a table showing the particle concentration vs size?

No. The manual has a table by concentration:
Level Color Particles/Liter
1 blue 500
2 yellow 1000
3 yellow 2000
4 yellow 3000
5 red 4000
6 red >5000
I presume that it's measuring dust particles, not aerosols.

>What type of resistor was it?

It had a ceramic case, so it could have been either metal film, wire
wound, some kind of bulk resistivity component. Most of the smoke
seemed to be coming from the scorched PCB.

>Why did the resistor give off particles?

It didn't. The PCB is what was producing the smoke.

>Was it hot enough to give off smoke?

It was hot enough to scorch the PCB, so I didn't think it would be
useful to also burn my fingers. Also, it's not very safe to shove my
fingers into a live AC powered device. I had an IR thermometer handy,
but neglected to use it.

>Could you detect the source by smell?

No. The entire office was full of burning resistor stench. There was
no visible smoke. I've had some experience chasing down overheating
computers and power supplies inside server farms. The concentration
of potential smoke sources and the high volume dispersible nature of
the air flow in an ISP's server farm makes this a difficult problem.
Lacking an IR imager, I just shoved a rubber hose into my nose, and
sniffed for maximum smoke stench among the multitude of exhaust ports.
About ever 15 minutes, I had to go outside to clear my nose. The
olfactory sensitivity comes as a side effect from being a werewolf:
<http://members.cruzio.com/~jeffl/nooze/werewolf.txt>

Sniffing for smoke in my small office created a different problem. The
flow of HVAC air would disperse smoke over the entire office making it
seem like everything was belching smoke. I immediately turned off the
ceiling fans. That helped but required that I purge the air about
every 10 minutes to prevent a build up of too much smoke.

I also made the mistake of thrashing around the office, disturbing
books and boxes laden with dust. Just touching a computah would cause
it to unload an almost invisible cloud of dust into the air via the
power supply or case fan. It was difficult to find the source without
being able to touch or move anything.

The overly sensitive Nikken AQM also created a problem. It would go
tilt fairly quickly even at a fair distance from the source of smoke.
I needed a smoke attenuator which was provided by restricting the air
flow with a somewhat lint free rag and some duct tape.

Once the procedure was established, it was very easy to find the
source of the smoke.

I use the Dylos DC1100 PRO, which is a laser particle counter. It shows
the particle count for two size ranges of particles: 0.5 micron to 2.5
microns, and greater than 2.5 microns. I believe it discriminates between
particle sizes by measuring the width of the pulse as a particle passes
through the light gap.

http://www.dylosproducts.com/ornodcproair.html

I have two units and I am always amazed at how well the readings agree
between them.

I wonder how the Dylos and Nikken would compare in ability to
discriminate between different size particles. Does the Nikken have more
size ranges?

No. The Nikken was designed for people with allergies or health
issues and may be associated with aroma-therapy which is hinted in the
terse manual. A look at their web pile will show their intended
audience. It is NOT a precision instrument.
<http://www.nikken.com>
My guess(tm) is that it is simply looking for large particles, which
comprise most of the lung irritants.

Photos:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/>

The hole in the intake nozzle is for the translucent tube that feeds
the intake of the light box.
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-01.jpg>

CAM-003 Light box:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-02.jpg>

PCB. Note the two push buttons and about 5 pots:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-04.jpg>
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-03.jpg>

Exhaust fan:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-05.jpg>

View from the exhaust end:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-06.jpg>
The metal plate in the middle is floating and not connected to the
other sheet metal. My guess(tm) is that it's a static brush, intended
to strip off any charge from the dust particles that might cause them
to stick to the metal duct walls.

Serial number sticker:
<http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/Nikken-AQM-07.jpg>


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Mon, 30 Jun 2014 21:13:17 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

Photos:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%20Monitor/

I dumped 3 PDF files into the above directory which are scans of the
English language parts of the user manual.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Monday, June 30, 2014 3:05:42 PM UTC-4, gyroma...@gmail.com wrote:

Hi,



This message is related to my earlier request for advice in the topic 'finding electronics design and fabrication expertise for a project'.



Because of the kindness of the group members here, I am posting more details about the project and aims.



The overall aim is to develop and deploy inexpensive 'personal' air pollution monitors. For the environment in which I am interested, a major pollutant concern is particulates arising from biomass combustion, coal burning, and car exhaust.



Although these may be inconsistent aims, I am interested in having a device that...

- can measure particulate concentrations (and perhaps temperature and humidity levels)

- is low cost, so that many devices can be deployed within a constrained project budget

- has a good degree of concordance (at least qualitatively) with accurate stationary monitoring stations

- can be read with an app on a cellphone or similar device (bluetooth?)

- is convenient to the wearer of the device, e.g, is robust and has the ability to run on batteries for a few days at a time



I anticipate that a user (or environmental health scientist or health care professional guiding the users) might want to record reading at several points during the day, not continuously.



There are several projects I have found on the web focused on devices to quantify particulates in the air, but I don't think that they satisfy the aims above.



The closest instrument that I could find is detailed in a PhD dissertation by David Holstius, a chapter of which I have posted here:



https://www.dropbox.com/s/azs0dqzgpffppl1/Holstius2014dissertation_Ch3.pdf



Because of my lack of training in the field of electronics, I do not know if the detection method, components, and overall design chosen by this individual would be appropriate as a starting platform to achieve the aims above.



Any input or suggestions would be greatly appreciated.



Thank you again.



-gyro

Hello Sir,
Thanks for the detailed description, it
appears that this is a large project,
and would need considerable time, effort
and money. There are two aspects --
detection and measurement. The first is
straightforward -- a simple phototransistoe,
would work as a detector - like in a
smoke detector. Measurement is tough,
since then your device has to be calibrated
against a test bench. What is the test-bench ?

 

[Adrian Jansen]

On 1/7/2014 8:13 AM, Phil Hobbs wrote:

The dust is pretty large compared with diesel smoke particles, so it
doesn't penetrate very far into your lungs. They got rid of the
asbestos awhile back, which was a pity. Chrysotile asbestos is nasty,
serpentine basically isn't.

Cheers

Phil Hobbs

According to my reference, its serpentine ( blue, mostly ) asbestos
which is the bad one, chrysotile ( white ) asbestos is relatively safe.
Can you quote a source for the data ?

--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Note reply address is invalid, convert address above to machine form.

 

[DTJ]

On 01-Jul-14 3:05 AM, gyromagnetic@gmail.com wrote:

Hi,

This message is related to my earlier request for advice in the topic 'finding electronics design and fabrication expertise for a project'.

Because of the kindness of the group members here, I am posting more details about the project and aims.

The overall aim is to develop and deploy inexpensive 'personal' air pollution monitors. For the environment in which I am interested, a major pollutant concern is particulates arising from biomass combustion, coal burning, and car exhaust.

Although these may be inconsistent aims, I am interested in having a device that...
- can measure particulate concentrations (and perhaps temperature and humidity levels)
- is low cost, so that many devices can be deployed within a constrained project budget
- has a good degree of concordance (at least qualitatively) with accurate stationary monitoring stations
- can be read with an app on a cellphone or similar device (bluetooth?)
- is convenient to the wearer of the device, e.g, is robust and has the ability to run on batteries for a few days at a time

I anticipate that a user (or environmental health scientist or health care professional guiding the users) might want to record reading at several points during the day, not continuously.

There are several projects I have found on the web focused on devices to quantify particulates in the air, but I don't think that they satisfy the aims above.

The closest instrument that I could find is detailed in a PhD dissertation by David Holstius, a chapter of which I have posted here:

https://www.dropbox.com/s/azs0dqzgpffppl1/Holstius2014dissertation_Ch3.pdf

Because of my lack of training in the field of electronics, I do not know if the detection method, components, and overall design chosen by this individual would be appropriate as a starting platform to achieve the aims above.

Any input or suggestions would be greatly appreciated.

Thank you again.

-gyro

Maybe this could be a starting point. They are cheap enough.

<https://www.google.com.au/search?q=sharp+dust+sensor>

 

[Phil Hobbs]

On 6/30/2014 9:14 PM, Steve Wilson wrote:

Phil Hobbs <hobbs@electrooptical.net> wrote:

AFAIK size measurement is always done by thresholding the pulse
heights. The scattered light power goes as the sixth power of the
particle radius. (I've recently reverse-engineered several such
units for two court cases, and they all worked that way.)

Cheers

Phil Hobbs

Thanks. I was working from some description I found online, but that
makes a lot more sense. It is far easier to discriminate pulse
amplitudes than pulse widths.

I wonder if the scattered light power flattens out above some radius?
For example, if the particle size is above 2.5 microns, does the
scattering change? For example, Raleigh scattering is effective for
particles much smaller than the wavelength of the light. I believe it
goes as the fourth power of wavelength:

http://en.wikipedia.org/wiki/Rayleigh_scattering

Yes. When the particles are big enough to be really opaque, they start
looking like geometric obstacles, so that the scattered light goes like
the intercepted area.

A fine point is that as the particles get larger, the light scatters
into a smaller and smaller range of angles around the incident k vector.

Other approximations are used for larger particles:

http://en.wikipedia.org/wiki/Light_scattering_by_particles

It's hard to tell which approach would be best suited for typical
air quality measurements, such as mold spores and dust particles.

Dark field light scatter, where the laser beam, air flow, and receive
path are mutually perpendicular is good medicine. Being 90 degrees off
axis reduces the dynamic range, because larger particles, which scatter
a great deal more light, scatter most of it in the forward direction.

Interferometric systems, which are sensitive to amplitude rather than
intensity, don't suffer as badly from this. (Power goes as amplitude
squared.)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Steve Wilson]

Jeff Liebermann <jeffl@cruzio.com> wrote:

On Tue, 01 Jul 2014 00:24:21 GMT, Steve Wilson <none@nospam.com
wrote:

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg

I could not find a user manual for your Nikken. If you have a pdf and
can spare the time, could you upload it to your web site?

Sure. I'll scan it later tonite.

Please don't spend the time. I found a used one on eBay and I'm sure it
will come with a manual.

This is a very interesting way to use a particle counter. I have some
questions:

How does the Nikken operate?

My guess(tm) is by optical scattering. The light show is inside the
black box with the air hose intake. See photos below. I didn't take
apart the box, but with 4 wires going into the box, it's a likely
guess.

I'll see if I can take it apart and get the actual circuit.

Is there a table showing the particle concentration vs size?

No. The manual has a table by concentration:
Level Color Particles/Liter
1 blue 500
2 yellow 1000
3 yellow 2000
4 yellow 3000
5 red 4000
6 red >5000
I presume that it's measuring dust particles, not aerosols.

I'm interested to find the size range. I'll compare it with the Dylos and
see if that helps.

What type of resistor was it?

It had a ceramic case, so it could have been either metal film, wire
wound, some kind of bulk resistivity component. Most of the smoke
seemed to be coming from the scorched PCB.

Why did the resistor give off particles?

It didn't. The PCB is what was producing the smoke.

Was it hot enough to give off smoke?

It was hot enough to scorch the PCB, so I didn't think it would be
useful to also burn my fingers. Also, it's not very safe to shove my
fingers into a live AC powered device. I had an IR thermometer handy,
but neglected to use it.

Could you detect the source by smell?

No. The entire office was full of burning resistor stench. There was
no visible smoke. I've had some experience chasing down overheating
computers and power supplies inside server farms. The concentration
of potential smoke sources and the high volume dispersible nature of
the air flow in an ISP's server farm makes this a difficult problem.
Lacking an IR imager, I just shoved a rubber hose into my nose, and
sniffed for maximum smoke stench among the multitude of exhaust ports.
About ever 15 minutes, I had to go outside to clear my nose. The
olfactory sensitivity comes as a side effect from being a werewolf:
http://members.cruzio.com/~jeffl/nooze/werewolf.txt

Sniffing for smoke in my small office created a different problem. The
flow of HVAC air would disperse smoke over the entire office making it
seem like everything was belching smoke. I immediately turned off the
ceiling fans. That helped but required that I purge the air about
every 10 minutes to prevent a build up of too much smoke.

I know the stench of burning pcb. It goes everywhere. Unfortunately, I
also know the source. It is usually something I did.

I also made the mistake of thrashing around the office, disturbing
books and boxes laden with dust. Just touching a computah would cause
it to unload an almost invisible cloud of dust into the air via the
power supply or case fan. It was difficult to find the source without
being able to touch or move anything.

The overly sensitive Nikken AQM also created a problem. It would go
tilt fairly quickly even at a fair distance from the source of smoke.
I needed a smoke attenuator which was provided by restricting the air
flow with a somewhat lint free rag and some duct tape.

Once the procedure was established, it was very easy to find the
source of the smoke.

I wonder how the Dylos and Nikken would compare in ability to
discriminate between different size particles. Does the Nikken have
more size ranges?

No. The Nikken was designed for people with allergies or health
issues and may be associated with aroma-therapy which is hinted in the
terse manual. A look at their web pile will show their intended
audience. It is NOT a precision instrument.
http://www.nikken.com
My guess(tm) is that it is simply looking for large particles, which
comprise most of the lung irritants.

It is interesting that it responds to the particles from an overheated
pcb. I don't know what the size range would be, but that may be something
I could try when the unit arrives and I can compare it with the Dylos.

Photos:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/

The hole in the intake nozzle is for the translucent tube that feeds
the intake of the light box.
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-01.jpg

CAM-003 Light box:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-02.jpg

PCB. Note the two push buttons and about 5 pots:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-04.jpg
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-03.jpg

Exhaust fan:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-05.jpg

View from the exhaust end:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-06.jpg> The metal plate in the middle is floating
and not connected to the other sheet metal. My guess(tm) is that it's
a static brush, intended to strip off any charge from the dust
particles that might cause them to stick to the metal duct walls.

Serial number sticker:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/Nikken-AQM-07.jpg

Thanks for the time and effort you put in to answer my questions.

 

[Steve Wilson]

Jeff Liebermann <jeffl@cruzio.com> wrote:

On Mon, 30 Jun 2014 21:13:17 -0700, Jeff Liebermann <jeffl@cruzio.com
wrote:

Photos:
http://www.learnbydestroying.com/jeffl/Nikken%201394%20Air%20Quality%2
0Monitor/

I dumped 3 PDF files into the above directory which are scans of the
English language parts of the user manual.

Very interesting. I'm sorry I didn't catch you in time to save you the
effort. But now I am really interested in taking the thing apart to find
out how it works. Thanks to Phil's work, we have a pretty good idea what to
expect in the circuits. If those are present, it's a good lead to what's
inside the box.

I'll take some pictures if I can get in without destroying it.

 

[Steve Wilson]

Jeff Liebermann <jeffl@cruzio.com> wrote:

I dumped 3 PDF files into the above directory which are scans of the
English language parts of the user manual.

Thanks again. Just for fun, I uploaded 3 files showing the operation of the
Dylos.

This shows a normal count in my apartment. The two counters agree to about
1%, which I found phenominal.

http://www.sed.comuf.com/particle/dsc09392.jpg

Here shows a higher count in a stairwell. Still very good agreement.

http://www.sed.comuf.com/particle/dsc09396.jpg

Here is a prototype particle filter I am working on. About 40dB reduction
in particle count. That's pretty good for 0.5 to 2.5 micron particles. They
are very hard to filter without a HEPA, which is very expensive for good
air flow.

http://www.sed.comuf.com/particle/3b9515e7.jpg

 

[Steve Wilson]

Steve Wilson <none@nospam.com> wrote:

PS, I'm mainly interested in the left column, which shows particle count
for sizes between 0.5 and 2.5 micron.

The right column shows particle sizes above 2.5 micron. I'm not so much
interested in these because they don't have the same tendency to lodge in
the lungs. They also tend to run about one-tenth the number of the
smaller particles, so if you know one, you automatically know the other.
Within statistical error, of course

I have no idea what the particle count would be for sizes below 0.5
micron.

There seems to be little information on the health effects, or what size
ranges are filtered by ordinary PM 100 air filters. The 3M description
covers a very broad range:

http://www.3m.com/product/information/P100-Particulate-Filter-
Respirator.html

The health effects seem to be ill-defined. Here is an excerpt from a
student lesson:

"The article “Particles in Practice: How Ultrafines Disseminate in the
Body” raises questions about how ultrafine particles smaller
than 100 nanometers (or 0.1 ľm) are able to be absorbed into the body and
distributed in the cells. They do not appear to be
encapsulated by macrophages and seem to be entering cells and transported
throughout the body by other, yet unknown,
mechanisms. This has significant implications for the potential health
effects caused by particles in this size range."

https://www.niehs.nih.gov/health/assets/docs_a_e/ehp_student_edition_less
on_particles_size_makes_all_the_difference.pdf

These issues are very significant for the design of particle filters to
improve indoor air quality.

 

[Phil Hobbs]

On 7/1/2014 1:19 AM, Adrian Jansen wrote:

On 1/7/2014 8:13 AM, Phil Hobbs wrote:

The dust is pretty large compared with diesel smoke particles, so it
doesn't penetrate very far into your lungs. They got rid of the
asbestos awhile back, which was a pity. Chrysotile asbestos is nasty,
serpentine basically isn't.

Cheers

Phil Hobbs

According to my reference, its serpentine ( blue, mostly ) asbestos
which is the bad one, chrysotile ( white ) asbestos is relatively safe.
Can you quote a source for the data ?

Thanks for prodding me--looks like I was completely off track.

The Wikipedia page talks about chrysotile and serpentine being the same
thing, and amosite and crocidolite (which I'd never heard of) as the
nasty carcinogenic ones.

Of course even completely inert mineral needles will cause fibrosis if
you inhale enough of them.

Whether that's enough to justify forcing millions of drivers to use
inferior brake pads is a policy question. (Nowadays brake pads have to
warm up to achieve their maximum effect, whereas asbestos ones didn't.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Phil Hobbs]

On 7/1/2014 12:58 AM, jurb6006@gmail.com wrote:

"Unless you use reflection, like in an optical smoke detector. Then
0%
is the baseline. He could probably count individual particles"

That may solve a problem but it creates another.

Then the mirror has to be cleaned.

That's a perennial problem with optical sensors. I once talked with a
guy who made optical sensors for cracks in railway rails. Trains are
_dirty_, and the only way they were able to keep their optics clean was
to continuously blow compressed air out of the optical port.

Now if this thing is allowed to have moving parts we can deal with
that. In fact even a lens would have to be cleaned sooner or later
but a mirror would of course be worse. Emitting surface, detecting
surface and then reflecting surface. Bad enough without that
reflector.

But then, that is all up to the designer. Maybe it would be better.
We are still a bit scant on details until - well - whatever.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[George Herold]

On Monday, June 30, 2014 7:23:04 PM UTC-4, Jeff Liebermann wrote:

On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:



You want to detect particulate matter in the air, and this

is going to be optically because you just do not have many other choices.



It's called a nephelmometer and uses light scattering. I have a

Nikken #1394 Air Quality Monitor:

http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg

I don't think this model is sold any more. The photo is me using it

to find the source of the burning smell in the office. It turned out

to be an overheated resistor inside the UPS in the photo. The unit is

quite sensitive. I can stamp my feet on the rug and cause the graph

to almost go full scale from the dust. Same with a couch or chair.

You could probably clone the function quite easily.



More:

http://www.nwcg.gov/pms/pubs/SMG/177-186.pdf

Oh good, I was going to say that besides optical you could
also pass the air though a filter and then see/weight what the filter collects
it's not that fast though.

George H.

http://en.wikipedia.org/wiki/Nephelometer

Overkill:

http://www.esrl.noaa.gov/gmd/aero/instrumentation/neph_desc.html





--

Jeff Liebermann jeffl@cruzio.com

150 Felker St #D http://www.LearnByDestroying.com

Santa Cruz CA 95060 http://802.11junk.com

Skype: JeffLiebermann AE6KS 831-336-2558

 

[John Larkin]

On Tue, 01 Jul 2014 15:19:43 +1000, Adrian Jansen <adrian@qq.vv.net> wrote:

On 1/7/2014 8:13 AM, Phil Hobbs wrote:

The dust is pretty large compared with diesel smoke particles, so it
doesn't penetrate very far into your lungs. They got rid of the
asbestos awhile back, which was a pity. Chrysotile asbestos is nasty,
serpentine basically isn't.

Cheers

Phil Hobbs

According to my reference, its serpentine ( blue, mostly ) asbestos
which is the bad one, chrysotile ( white ) asbestos is relatively safe.
Can you quote a source for the data ?

Serpentine is California's State Rock. It's pretty, green with white streaks.




--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[John Larkin]

On Mon, 30 Jun 2014 21:58:58 -0700 (PDT), jurb6006@gmail.com wrote:

"Unless you use reflection, like in an optical smoke detector. Then 0%
is the baseline. He could probably count individual particles"

That may solve a problem but it creates another.

Then the mirror has to be cleaned.

Mirror? A laser or LED shoots out light and a photodiode catches light scattered
by particles. Shine a laser pointer across the room and see the dust or smoke
particles... no mirror involved.

Photoelectric smoke detectors work like that.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[Mikko OH2HVJ]

Jeff Liebermann <jeffl@cruzio.com> writes:

On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You want to detect particulate matter in the air, and this
is going to be optically because you just do not have many other choices.

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg

Nice pictures and especially I like the domain name! Could the
metal tunnel be an electrometer circuit ? The center plate might be
connected to the LMC6001, which is quite common in aerosol
electrometers. What's inside the black box marked with 'CAM-003' ?

--
Mikko OH2HVJ

 

[Jeff Liebermann]

On Tue, 01 Jul 2014 21:56:23 +0300, Mikko OH2HVJ
<mikko.syrjalahti@nospam.fi> wrote:

Jeff Liebermann <jeffl@cruzio.com> writes:

On Mon, 30 Jun 2014 13:52:57 -0700 (PDT), jurb6006@gmail.com wrote:

You want to detect particulate matter in the air, and this
is going to be optically because you just do not have many other choices.

It's called a nephelmometer and uses light scattering. I have a
Nikken #1394 Air Quality Monitor:
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg

Nice pictures and especially I like the domain name! Could the
metal tunnel be an electrometer circuit ?

Yes, it could but I have no clue how one would measure dust
accumulation using an electrometer. Besides, the forward mounts for
the insulate plate uses nylon insulators, which are hygroscopic, and
would leak badly if uses as an electrometer. Yet, there's a very low
input current op amp on the board. If some spare time finds me, I'll
investigate the patents and maybe try to reverse engineer the PCB.

The center plate might be
connected to the LMC6001, which is quite common in aerosol
electrometers.

<http://www.ti.com.cn/general/cn/docs/lit/getliterature.tsp?genericPartNumber=lmc6001&fileType=pdf>

>What's inside the black box marked with 'CAM-003' ?

I don't know. I have to go back inside anyway. I just noticed on one
of my photos that I forgot to reinsert all the connectors. Argh.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558