bringing this question asked from @bostonfern
Also, Are the PID VOC meter, which also measures f...
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by stevie |
February 06, 2020 21:39 |
bringing this question asked from @bostonfern
Also, Are the PID VOC meter, which also measures formaldehyde, accurate? Are they capable of measuring many different kinds of VOCs in one single scan or I have to measure one by one? Are they accurate?
Answers came in from @nshapiro
"You could try a summa canister: http://summacanister.com/ (they are offered by many labs not just this one). it is basically a sterile bowling ball that has all of the air vacuumed out of it and then you put it in your house and open the valve and it sucks in air at a known rate and then you take that to the lab and they can run a full analysis on all the chemicals they find in there. my guess is that it would be under 500 including shipping and analysis.
The other option is some people will rent you instruments so you could rent a fancy HCHO meter for a day and get all your measurements that way. without the huge investment.
BUT saying all this, you might want to just try remediation as often in manufactured housing its hard to get rid of the engineered woods that off-gas hcho.... I would avoid spending [the money on a PID VOC meter]. I'm also not sure if they can measure as low as you would want as you will be looking at parts per billion not parts per million. They are often made for use in heavy industry where they have crazy high levels."
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Wow i wasn't familiar with PID sensors. I skimmed the Wikiepedia page here:
And also found this pretty readable post about limitations or possible issues with them: https://www.levitt-safety.com/blog/the-problem-with-pids/
Do we know how much they cost? I'm guessing a lot? Google Shopping suggests maybe $500-5000: https://www.google.com/search?tbm=shop&q=pid+sensor+gas
As to detection, Wikipedia says down to parts per billion? from sub parts per billion to 10 000 parts per million (ppm)
from sub parts per billion to 10 000 parts per million (ppm)
The one in the article above was $3000-4000 -- https://www.google.com/search?tbm=shop&q=tiger+voc#spd=857929050906658907
It says it is sensitive down to 1 part per billion: A robust VOC detector Tiger provides a dynamic detection range of 0 to 20,000 parts per million (ppm) with a minimum sensitivity of 0.001ppm (1 ppb), offering the widest measurement range of any other VOC detector on the market.
A robust VOC detector Tiger provides a dynamic detection range of 0 to 20,000 parts per million (ppm) with a minimum sensitivity of 0.001ppm (1 ppb), offering the widest measurement range of any other VOC detector on the market.
But they seem to have a pretty tough calibration procedure involving some kind of calibration machine.
I did see some available for rent, so maybe they'd come precalibrated?
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These instruments are all based on GC detectors. So your best approach is to look at other GC detectors to see which one fits your needs. One good fit is MS ( mass spectrometer). It is also very expensive. Another that might fit your needs is an FID ( flame ionization detector). It takes a gas flame, which makes it less desirable than a PID.
There are a number of other GC detectors, many of which are kind of obscure. Take a look at those and see if any fit the VOC/ TOC (total organic carbon) requirements. Good luck.
I'm becoming familiar with the MeteoMex suite of sensors from @robert_winkler that includes tVOC monitoring and could serve as a low-cost place to start investigating. There's not so much about these sensors on Public Lab yet, but you can read more about them here: http://www.meteomex.com and see an example output here.
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