Authors: Jack Driscoll and Jennifer Maclachlan, PID Analyzers, LLC
|Fixed air pollution monitoring stations in the US have been established for several decades. These are large, very expensive and difficult to move to new or temporary locations. A portable analyzer was described last year (Paper# 180-18P) that was compact and quite sensitive for VOC’s. As a result of comments, at the Conference, a new inexpensive sensor package was designed and this will be discussed in this paper.|
We have developed a sensor package for monitoring some of the agents and products that contribute to photochemical smog formation, namely: VOC’s, O3, NO2 and solar radiation. The analyzer incorporates a photoionization detector (PID) that measures VOC’s down to 10 ppb, a solar radiation sensor and improved electrochemical sensors for ozone (10 ppb) and nitrogen dioxide (20 ppb). The package is housed in a NEMA 4 enclosure for protection from the elements and has a NiMH battery that will last between 60 to 90 days
A number of modifications have been made to improve battery life since the portable analyzer described at Pittcon 2011 lasted only 12 hours. Design considerations included going to diffusion sensors rather than continuously purged. Now there are no moving parts, The sample time was changed from continuous to a sample every 5 minutes. This will still give us enough data to obtain a graphic image of the PC Smog problem in the area being sampled and allow the analyzer to be put in a sleep mode to conserve power. If we sample every 5 minutes, we collect six thousand samples per month.
With the datalogger, there are a number of options for collecting the data. These include storage in the unit and collection on a PC when the battery needs to be changed, wireless transmission to a local PC, sent to a network using a gsm modem if the data is needed quickly. We will locate sites near a continuous monitoring trailer and compare data with a continuous monitoring network for the same pollutants.