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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