Stack Testers  do it in real time!- Ed Burgher & Jim Mills

Stack particulate testing has always been a challenging occupation and life is about to get even more interesting with EN14181 on the horizon. The current reference methods rely on extractive sampling onto a filter which is then transported to a laboratory for weighing on a balance and if all goes to plan you get the result a week or so after the test and in the intervening time, hope and pray you passed. In a way it’s a little like old fashioned photography. Remember the days when you had to put film in a camera, take a few shots, send them away for developing only to find out, a couple of weeks later that they didn’t turn out and you had lost the lot? Nowadays we have digital cameras that not only give instant results but can deliver high quality movies in real time all on something the size of a "box brownie" Current stack testing methods are a bit like film based photography, one exposes a filter to the stack sample which then goes off for weighing and after some considerable time you get the results back, if your lucky! The introduction of a new type of stack particulate monitor promises to do for stack testing what the digital camera did for photography, as it provides instant results, provides a "moving picture" of the PM concentration and gives assurance that the test is progressing to plan.

The TEOM-SPM (Source Particulate Monitor) operates on the same basis as the reference methods. It samples and weighs the particulate matter on a filter. The difference is it does all this inside the stack, with better precision, in real time and provides results as you go. Too good to be true? The US EPA don’t think so, they have recently designated the new method approved the new method as an alternative to the reference method and in Europe tests carried out by the German TUV show that the system is able to match the accuracy of the European reference methods and in most cases provide better precision and lower detection limits.

With the strict quality assurance requirements of EN14181 coming into force later this year it will be very difficult to meet the requirements for PM using conventional sampling technology, even with the most skilled of stack testing personnel. Imagine the horror of conducting a three day long QAL2 test, with all the associated costs, such as the stack testing team, plant disruption, special running conditions, etc. only to find after the tests were concluded that the results did not meet requirements and have to be repeated possibly at even greater cost! Would it not be a great advantage to be able to see what the results are as they develop, to be sure that you are "in spec" as the test progresses and be able to take corrective action to ensure that the test is successful in every sense? The following article describes in detail how the TEOM - SPM is able to achieve this.