Optical detector rings a bell, 20 years ago we had a Forward Scatter
Meter, we used it at the plant to measure the density of the fog. Had
nothing to do with humidity but it was for visibility. If I remember
correctly it had a shielded IR light source on one arm facing a shielded
photo detector array on an opposite arm about 2 meters separating them.
I think they use a similar device at airports. Maybe a device of that
type may work on a smaller scale. Zero point would be no interference,
high level would be the point at which the air quality is uninhabitable,
and possibly a logarithmic scale in between.
Pat
On Thu, Aug 29, 2013 at 11:04 AM, Wayne Thayer wrote:
> That's different thinking!
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rivera, Raye
> Sent: Thursday, August 29, 2013 1:59 PM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> If this is an optical detector, why do you need actual smoke? Put a
> piece of tinted plexiglass in the detector as a calibration standard
> in the field. You can figure out what density of particles it is
> equivalent to in a lab with a particle counter.
>
> Best regards,
> Raye Rivera
> QA Manager * Canoga Perkins * 818-678-3872 * [log in to unmask]
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
> Sent: Thursday, August 29, 2013 10:35 AM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> I think what I'm going to try next is two wirewound resistors glued
> together with some ceramic paste, or maybe just build a hammock
> between them with some aluminum foil. Then try a drop or two of the
> liquid they use on model trains to simulate smoke. If that doesn't
> get me anywhere, then maybe the heating element from an e-cigarette.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
> Sent: Thursday, August 29, 2013 1:17 PM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> Wayne - agree. That's why I pointed you to Gentex. It's optical.
> Used to be that all commercial aircraft had these detectors from
> Gentex
>
> Steve C
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
> Sent: Thursday, August 29, 2013 1:03 PM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> In an ionization-based detection system (technically illegal in my
> application because of the radioactive source required), you can check
> sensitivity by looking at the leakage current through the ionization
> chamber. Most of these "in circuit test" systems simply put a
> resistor across the ionization chamber and measure the time it takes
> set off the alarm.
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
> Sent: Thursday, August 29, 2013 12:51 PM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> Wayne,
>
> That is a good point about the smoke detectors, since there are two
> types - the ionization types and the particulate types that work by
> scattering of light.
> Look at FAQ #3 at this site -
> http://www.gentex.com/fire-protection/technical-support
> It would appear that they have the calibration and degradation issues
> worked out. I may still know some people there, but not sure how much
> help that would be in this situation.
>
> We used to ignite a ribbon of Mg to coat the inside of an integrating
> sphere with white powder. If you can combust tiny performs of Mg, or
> nanofoil as someone else suggested, that seems like it might satisfy
> your combustion quantity issue - although may create another issue
> with transport and handling....
>
> Steve C
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
> Sent: Thursday, August 29, 2013 12:33 PM
> To: [log in to unmask]
> Subject: Re: [TN] Blowing Smoke
>
> Hi Dennis-
>
> Yes, as you and Richard have pointed out, calibrating particle sensors
> is not un-mapped territory. The systems are accurate and worthy of
> withstanding the rigors of lawsuits.
>
> But we can all see that there is a huge gulf between that kind of
> calibration and the other end of the spectrum, such as seeing whether
> a smoke detector is working OK.
>
> Another point in that gulf is a counter designed to control a HEPA in
> a room where a person has allergies. For that, they don't use a laser
> for illuminating the particles, they just use an IR LED. Hence they
> don't know if they are looking at one giant particle or a bunch of
> tiny ones. But they actually appear to be useful anyway, and the cost
> for the sensor from DigiKey is $12. Sharp tells you right up front on
> the data sheet that the LED will fade over time, by as much as 50%,
> with a corresponding drop in sensitivity. Also, the calibration
> curves provided in the data sheet show a very wide range of "typical"
> calibration slopes.
>
> So my gut tells me there should be some way of making a repeatable
> experiment that could be used for comparing these cheap sensors to
> each other and to watch the degradation in performance vs. time. I
> need to vaporize a defined amount of material in a closed volume.
> Turns out to be more challenging than I thought! It seems the
> diffusion of the vaporized material is actually the easy part.
> Complete combustion of a defined amount of material is hard.
>
> Wayne
>
> From: Dennis Fritz [mailto:[log in to unmask]]
> Sent: Thursday, August 29, 2013 11:27 AM
> To: Wayne Thayer
> Subject: Re: [TN] Blowing Smoke
>
> Good luck on this one, especially the "The idea is a cheap sensor"
> part.
>
> Particle measurment in either air or liquid is pretty well developed.
> IEST is the standards organization and there are also IEC
> international regulations/certifications
>
> I googled "air particle counter calibration" and a lot of stuff came
> up - most all probably too complicated for what you need - "cheap".
> However, this link gives some background on your problem and a bit of
> "who certifies what".
>
>
> http://www.particle.com/wp-content/uploads/downloads/2012/02/WP-MET-ONE-ISO-
> 21501-Calibration-of-APC-from-Metrology-Perspective-US.pdf
>
> Good luck.
>
> -----Original Message-----
> From: Wayne Thayer <[log in to unmask]<mailto:[log in to unmask]>>
> To: TechNet <[log in to unmask]<mailto:[log in to unmask]>>
> Sent: Thu, Aug 29, 2013 10:06 am
> Subject: Re: [TN] Blowing Smoke
>
> To answer previous question:
>
>
>
> The idea is a cheap sensor. 3rd world homes are notoriously smoky due
> to the
>
> cooking fire and due to kerosene lamps. Most of the smoke is carbon.
> There are
>
> lots of ideas for improving these homes (like LED lights with solar
> rechargers)
>
> so we can "improve their lot" by making it more healthy for kids to
> study inside
>
> (or maybe so they can buy stuff on the internet?). Anyway, the aid
> groups want
>
> a way to see what the bang for buck is in improving the indoor
> environment, so
>
> they need a sensor. These sensors work by shining an LED or laser
> through an
>
> air stream, and measuring the amount of light which is reflected
> off-axis by the
>
> particulates in the air.
>
>
>
> How does the bicycle pump (actually I'm imagining a disposable plastic
> syringe)
>
> pick up a defined amount of cigarette smoke? Maybe arrange a fixture
> which
>
> leaves the cigarette burning and allows the smoke to just rise into
> the open end
>
> of the syringe for a set amount of time, then put the plunger in.
> Might
>
> work-cheap to try!
>
>
>
> As to the other suggestions, such as the nichrome wire, I keep coming
> back to
>
> needing some kind of heated basket so I can make sure I burn 100% of
> whatever I
>
> put in there. A circulating fan and Brownian motion should make the
> environment
>
> pretty uniform, although with the tests I've been doing, I get a spike
> with an
>
> exponential decay as the particles settle. Still, the interior of the
> 5 gallon
>
> bucket appears pretty uniform, even though the peak duration is only
> about
> 40
>
> secs.
>
>
>
> Wayne
>
>
>
> From: Inge Hernefjord
> [mailto:[log in to unmask]<mailto:[log in to unmask]>]
>
> Sent: Thursday, August 29, 2013 4:45 AM
>
> To: TechNet E-Mail Forum; Wayne Thayer
>
> Subject: Re: [TN] Blowing Smoke
>
>
>
> Don't laugh now, I am serious. A kind of cycle pump, but with a very
> small
>
> diameter nozzle. Pull the handle and suck a second sniff of cigarett
> smoke,
>
> continue pulling handle until pump is filled with air/smoke mixture.
> Now press
>
> handle slowly and you get a constant stream of mixture. Simple and
> cheap.
> Guess
>
> the nozzle should be fractions of a millimeter.
>
>
>
> Inge
>
>
>
> On 28 August 2013 08:07, Wayne Thayer
>
> <[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]
> om<mailto:[log in to unmask]>>>
>
> wrote:
>
> OK, here's another problem I've been playing with (although it has
> little to do
>
> with IPC mission, it might be related).
>
>
>
> I am trying to build a system for measuring airborne particulates for
>
> humanitarian organizations looking for inexpensive ways to
> measure/monitor
>
> indoor air quality. There are cheap sensors available which might do
> the job,
>
> but they would need periodic re-calibration.
>
>
>
> So I need a controlled, extremely small amount of smoke. At first, I
> thought
>
> this would be trivial: Find a cheap part at DigiKey and put too many
> watts
>
> through it. Way too much smoke and too little control. Then I tried
> burning
>
> thin wires. Too irregular because sometimes they incinerate
> completely and
>
> other times they find a tiny defect and just burn that until the wire
> stops
>
> conducting. Then I tried just heating the wire enough to burn off the
>
> insulation. Still too irregular! I did just a few experiments and
> got 30%
>
> variation.
>
>
>
> Now I'm starting to think maybe a tiny piece of paper on an automotive
> cigarette
>
> lighter. That's a lot of power to get that glowing, and it is not
> convenient to
>
> attach to. Any other ideas?
>
>
>
> Wayne
>
>
>
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