scope:

This recommended practice covers Type F, Type G, and Type H fluid heaters and related equipment.

Within the scope of this recommended practice, a fluid heater is considered to be any thermal fluid heater or process fluid heater with the following features:

(1) Fluid is flowing under pressure.

(2) Fluid is indirectly heated.

(3) Release of energy from combustion of a liquid or gaseous fuel or an electrical source occurs within the unit.

This recommended practice does not apply to the following:

(1) Boilers (which are covered by NFPA 85, Boiler and Combustion Systems Hazards Code, or ANSI/ASME CSD-1, Controls and Safety Devices for Automatically Fired Boilers)

(2) Class A, B, C, or D ovens and furnaces (which are covered by NFPA 86, Standard for Ovens and Furnaces)

(3) Fired heaters in petroleum refineries and petrochemical facilities that are designed and installed in accordance with API 560, Fired Heaters for General Refinery Services; API RP 556, Instrumentation and Control Systems for Fired Heaters and Steam Generators; and API RP 2001, Fire Protection in Refineries

(4) Fired heaters commonly called reformer furnaces or cracking furnaces in the petrochemical and chemical industries

(5) Units that heat air for occupiable space or comfort

(6) LP-Gas vaporizers designed and installed in accordance with NFPA 58, Liquefied Petroleum Gas Code

(7) Coal or other solid fuel-firing systems

(8) Listed equipment with a heating system(s) that supplies a total input not exceeding 150,000 Btu/hr (44 kW)

The following types of heaters are covered by this recommended practice:

(1) Class F heaters, which have fluid inside the tubes with a relatively constant flow rate

(2) Class G heaters, which have fluid inside the tubes with a modulated flow rate and firing rate

(3) Class H heaters, which have a heat source (combustion or electricity) inside the tubes

Purpose. This recommended practice provides recommendations for fluid heaters to minimize the fire and explosion hazards that can endanger the fluid heater, the building, or personnel.