Upload
dr-jack-driscoll
View
664
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Monitoring photochemical smog components using a PID analyzers Model 102
Citation preview
Analysis of PPB Levels of (VOC’s) Photochemical Smog Components in Air with a Portable Analyzer
Jennifer L. Maclachlan & Dr. J.N. DriscollPID Analyzers, LLC
Sandwich, MAPaper # 180 - 18P
Introduction• Wanted to test the feasibility of monitoring ambient air with a compact
multisensor PID based instrument like the Model 102+• Air monitoring networks are very complex and very expensive ($250K)
Is it possible to obtain useable data from an inexpensive portable analyzer?
• We used a PID for measuring VOC’s; a Dual beam IR sensor for CO2 and an electrochemical sensor for NO2
• We wanted to determine the effect of the weather on VOCs and other components in the air
• We are located on Cape Cod just off a highway (Rt 130) in Sandwich, MA
• We are across from Otis AFB which is part of the MMR that covers an area of 30 sq miles
Technology
• VOC’s- Photoionization- ppb 0-100,000
• CO2 – Infrared Absorbance- ppm 0-5,000
• NO2 – Electrochemical- > 50 ppb
PID-102+ with Multiple Sensors
Photoionization Process
PID Schematic
• R + hv = R + + e-
Dual Beam IR
CO2 Spectrum Schematic
Photo of Model 102 wSnap on Heads
PID-102+ uP, Amplifier & Sensor Boards
Sampling Location: Cape Cod, MA
Ambient Air Monitoring Cape Cod
Nearest home was ca 1 mile
Indoor Air Monitoring
Outside Air- Winter Day
Outside Air- Raining
Outside Air- Snowy Day
NO2 ppb
Comparison of Weather Conditions on VOC Concentrations
Type of day Morning Afternoon
Winter < 10 ppb < 10 ppb
Rainy < 10 ppb 35-70 ppb
Snowy < 10 ppb 35-100 ppb
Summary• A portable multisensor instrument like the Model 102+ can be
used to provide valuable info on where to site VOC “hot spots” for future air monitoring stations
• The analyzer could be enclosed in a weather proof enclosure and mounted on a telephone pole with bluetooth capability for remotely collecting data
• Weather (rain or snow) does affect the VOC levels significantly as expected and the 102+ was able to detect this effect
• The NO2 sensor selected was not sensitive enough to measure ambient levels of NO2
• The PID and IR will work in this environment but other ppb level sensors are needed to complement the Model 102