This document establishes general principles for measuring the uniformity of furnace exposure of samples tested in accordance with the requirements of ISO 834‑1. This document specifies the type and location of instrumentation used to measure the temperature, velocity and oxygen content near the surface of simulated test samples. The surface of the simulated sample facing the furnace is gypsum board secured to cold-formed steel supports. This document does not include requirements for furnace performance. An intended use of data generated by the application of this document and the rational for the instrumentation described in this document are contained in the informative Annex A.