Air Flow Measurement Accuracy within a Particulate Laden Air Stream
Measuring the Air Flow in a duct can be difficult enough when the flow profile is not free from turbulence, disturbances, cyclonic flow, and reverse flow, but add to that particulate, ash, dust, or debris in the air, and it can almost be impossible. So, how do you get accuracy when trying to measure the Air Flow in a duct that has particulate, ash, dust, or debris in the air stream? The traditional way is to use a blast purge or blow back system that will take high pressure compressed air and blow it back through the high and low ports of the air flow pitot or flow element so that any particles, ash, dust, or debris is blown out of the ports on the probe. This not only uses a lot of compressed air, which needs to be completely dry to work properly, but it also requires a complex system of valves in order for this to be done automatically. If the blast purge or blow back is not done on a regular basis, and if the particulate, ash, dust, or debris level is high enough ...