ISO 14934-4:2014 provides guidance on the use of heat flux meters in fire testing applications, including the description and working principles of common heat flux meters and methods for their selection and maintenance. The guidance can also be applied to measuring heat flux from radiant panels and other large heat sources used to simulate the heat flux from a fire. It is applicable for all common testing purposes when measuring heat flux from radiant sources. ISO 14934-4:2014 also provides basic theory and working principles of heat flux meters and methods for selection, use, and maintenance of heat flux meters. Although it is particularly aimed at the application of heat flux meters in fire tests and experimental works of fire research, it can also serve as a guide for other research applications like research of boilers, combustion processes, etc. Instruments, which measure the transient temperature of a solid body of known mass and heat capacity to infer the heat flux (slug calorimeter type), are not covered by ISO 14934-4:2014.