API 550PT3 : 3ED 85

NOW WITHDRAWN Describes instrumentation for three types of tubular heaters: Heaters with natural draft; Heaters with forced-draft fans, induced-draft fans, or both; Heaters with forced-draft and induced-draft fans with a combustion air preheater. These heaters consist of heating coils, arranged in a refractory setting to provide radiant and convection heating sections. They are fired with gas, oil, or a combination of both. The flow of material through the coils is generally countercurrent to the flow of combustion gases to achieve good thermal efficiency.