PID Analyzers, LLC

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Wireless indoor air quality (IAQ) monitoring in classrooms and

laboratories (VOC's, CO, CO2, and T)

PID Analyzers, LLC

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Introduction

High levels of CO2 (>1,000 ppm) can result in students feeling drowsy or sick

Poor air quality in school classrooms is a serious problem now a “typical 700-square-foot classroom with 20 to 30 occupants ventilated by a standard HVAC system”. (Aiken, Tom, Cleanfax Online: http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-classrooms-with-air-quality-monitors)

We initially used a Model 114 IR Analyzer but we also designed a low cost single channel IR logger for CO2 to monitor labs, offices & class rooms

A positive benefit to improving IAQ in classrooms is that a number of studies have shown that improved air quality can lead to higher test scores. (Aiken, Tom, Cleanfax Online: http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-classrooms-with-air-quality-monitors)

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ASHRAE’S POSITION ON CARBON DIOXIDE (CO2) LEVELS

American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) has a guideline of 1,000 ppm CO2 for indoor spaces

CO2 has been used as a basis for ventilationCO2 levels are good predictors or surrogates for human

emitted bioeffluents (i.e., odors)If the ventilation rate is set so that 1000 ppm CO2 is not

exceeded and if CO2 is controlled by any method other than dilution, the effects of possible elevation of other contaminants must be considered.”

CO2 levels should be measured during the time of occupancy which is defined for the classroom as the time between initial occupancy in the morning and dismissal time for the students.

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CO2 Levels & Health Effects

325 - 350 ppm – background (normal) outdoor air level 750- 1,000 ppm - typical level found in occupied

spaces with reasonable air exchange. 1,000 – 2,000 ppm - level associated with complaints

of drowsiness and poor air. 2,000 – 5,000 ppm – level associated with headaches,

sleepiness, and stagnant, stale, stuffy air.  Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.

>5,000 ppm – Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma and even death.

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IR Sensor Schematic-CO2

PID Schematic-VOC’s

IR Sensor & VOC sensor Schematic

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IR spectrum of CO2 Dual Beam IR Meas. & Ref. Wavelengths

IR Spectrum for CO2

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2/1/2011 8:52 2/1/2011 9:07 2/1/2011 9:21 2/1/2011 9:36 2/1/2011 9:50 2/1/2011 10:04

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325326.3327.6

416416

370.5369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2367.9367.9367.9369.2367.9367.9367.9367.9367.9367.9

314.6

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154233439

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15678101181491199915991617

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VOC's and CO2 Variation in Laboratory

Series1Moving average (Series1)Series3Moving average (Series3)

ppb V

OC

(R

ed)

/

ppm

CO

2 (

Yell

ow

)

Laboratory 200 sq ft/person

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CO2 in Office (75 sq ft/person)

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Components of Single Channel Logger

45 hours for CO2150 Hours for EC

rechargeable

Enclosure

Battery

9

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Model 114 IR CO2 Photo of Classroom

CO2 in Classroom

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CO2 Variation in Different Locations Location & Description

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101112131415

0 200 400 600 800 1000 1200 1400

Variation of CO2

ppm CO2

Roo

m #

1 lab 4 people 2 office 3 people 3 home 2 people 4 classroom 15 students 4 teachers 5 outside air near office 6 class room 20 students 2 teachers 7 outside air on cc 8 Hotel room 9 Hotel corridor 10 classroom 25 people 11 classroom larger 40 people 12 classroom 10 people 13 classroom 3 people 14 classroom no people 15 classroom 13 people

CO2 Measurements

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Conclusions

CO2 is a good indicator of room air quality and problems can be found quickly and efficiently

Initial measurements were made with a CO2 Model 114 IR but a single channel CO2 dosimeter has been designed and will be available in the Fall 2012

Many rooms were found to be close to 1,000 ppm in homes, offices and classrooms in the winter. With adequate ventilation, warmer temperatures, average classrooms could be 750 ppm or lower

The Bluetooth slave module is capable of sending data 100-200’ to a master module in a PC