This Code provides uniform methods and procedures for testing the thermodynamic and fluid mechanical performance of air cooled heat exchangers, and for calculating adjustments to the test results to design conditions for comparison with the guarantee. The scope of this Code covers, but is not limited to, the testing of mechanical draft heat exchangers, of both the forced draft and induced draft types, natural draft heat exchangers, and fan assisted natural draft heat exchangers. From a heat transfer surface standpoint, this Code covers all tube bundle orientations, including: vertical, horizontal, and slanted conduit heat exchangers. Both bare surfaces and finned surfaces are included as conduit type heat exchanger components. While conventional round tubes with circular fins are assumed in this Code, the procedures can be modified by mutual agreement to apply to other surface configurations. While the cooling fluid is restricted to atmospheric air, the tube-side fluid can be any chemical element, compound or mixture, in single phase flow, liquid or gas, or in two phase flow. This Code is written under the assumption that the Air Cooled Heat Exchanger (ACHE) may be tested as having a discrete process stream or that only one process fluid stream is being investigated. In other cases, modifications must be made to the procedures presented. Such modifications shall be agreed by the parties to the test. The scope of this Code also includes, directly or by reference, recommended methods for obtaining data, measurements, observations, and samples to determine the following: (a) Physical Dimensions (b) Air Flow Rate (c) Air-Side Pressure Differential (d) Fan Driver Power (e) Sound Level (f) Atmospheric Pressure (g) Environmental Effects (h) Wind Velocity (i) Air Temperatures (j) Entering Air Temperature (k) Exit Air Temperature (l) Process Fluid Temperatures (m) Process Fluid Pressures (n) Process Fluid Flow Rate (o) Composition of Process Fluid (p) Percent capability (q) Process Fluid Pressure Drop.