What are the factors to consider when designing a suitable sampling system?
It is important when designing a sampling system to use materials that prevent gases from adsorbing to the surfaces of the sampling system. The best materials to use are fluoro-polymers, PTFE, TFE and FEP. Moisture condensing from the gas stream can cause blockages and flooding so it is important to remove any water condensing out by using a suitable water trap. Alternatively, water can be removed in the vapour phase by the use of Nafion tubing. For gases at high temperatures the sample stream should be cooled to within the operating range of the sensor and any particulate matter should be removed from the sample by using appropriate filters. Additional in-line chemical filters can also be incorporated into any sampling system design to remove any effects from cross-interfering gases.
