We have not established a formal standard for accuracy due to the wide variety of types, locations and applications for the equipment in question. We request that actual measurements be conducted for information such as stack height and diameter if facility plans are not available due to the age of the emissions unit. For taller, inaccessible stacks, this may involve using an inclinometer and a rangefinder. Information such as flow rate and temperature can be taken from design plans, old stack tests, or estimated based on process knowledge.
We do not expect facilities to conduct stack tests to obtain this information.