There are products manufactured by Land which can do what you are looking for. Specifically the Mark II 4500, is a sensor using green LEDs whose light travels through the stack and reflects back to the transceiver. The reflected amount of light is compared with the amount sensed and the particulate content is calculated from here. You may check their website at: http://www.landinst.com/comb/products/4500mkii.html
Hope this helps Jimmy Saldivias TECSIM Phone: 591-4-523438 Fax: 591-4-523413 website: http://tecsim.trading.net
downstream of working hepa filters the particulates before agglomeration are less than 0.5micron size. search for the companies making optical particle counters for use in air, such as met-one, pms of boulder colorado, hiac-royco, rion of japan, etc.
Hi Bill, Not sure of the type of emission you want to monitor, there are many types of instruments. Have a look at the TriboFlow http://www.auburnsys.com/technology.html We have used this for Dust Emission from Dust collectors Sensitivity range options available down to .000005 gr/dscf (~.01 mg/m 3 )
Not sure how accurate this device is, we are not using it for accurate readings, just indication. We have also used Opacity Meters (they can have problems, you would need to specify more detail about what you wanted to monitor)
You could either use continuous on-line monitoring system or use a Portable Particle counter the latter being more desirable, if the application is to check the integrity of HEPA filters from time to time.
Important Considerations are :
1) size of Particles to be measured 2) Clean room Classification
MET-ONE has range of Products, Pls check out their web site,
For this application there is a sensor that works with the triboelectricity method. I had the opportunity to install a net of this instruments to measure the particulate air coming out from the filter on a boiler (working with sunflower hull as fuel). The instrument work really good and the net was connected to a software for trends.
