The sample handling and conditioning system used by Entech Engineering can extract from one to 24 samples, individually or in composite, from the flue or vent gas ducts. One to four positive displacement pumps is used to draw samples from the gas duct to the trailer continuously. Depending on the applications, probes may vary from stainless steel to borosilicate to quartz and sample lines may vary from polyethylene to nylon to Teflon. Selection of the probe and sample-line material depend on the pollutant and sampling methodology. In most emission testing applications, the probes and sample lines are heat traced to prevent condensation.
After the sample pumps, flue or vent gas passes through a condenser to remove moisture in the gas. The conditioned sample then passes through a ten-micron filter where particulate matter and any carried over water droplets are removed. A control bypass valve is used to control flow to the instruments and to prevent pressure surges from reaching the instruments. Conditioned gas- sample passes through control valves and flow meters to the instruments for the analysis of individual gases Certified size A or B cylinders containing protocol gases are used to calibrate the sampling system and the individual analyzers while nitrogen is used to establish the instruments' zero point. After analysis, the samples are vented outside the trailer. The measured emissions are reported on a dry basis and are recorded on a variable speed strip chart recorder.