The burners covered by this specification are intended for use in packaged low pressure steam boilers or low temperature hot water generators having a thermal output capacity between 40,000 and 320,000 Btu/hr (11 722 and 93 783 watts (W)). The burner class should be determined in accordance with the availability or economics of the fuel supply and the intended application. Multi-fuel burners should be specified in order to ensure economic and reliable operation within the constraints of fuel availability and applicable environmental regulations

Selection factors and the best choice of options will vary depending on the size of the boiler that the burner is to be installed in. A spare burner should not be procured without knowing the specific boiler that it is intended to be used in. Variable fuel compositions and boiler configuration information needed when specifying a burner shall be known. The following items should be considered in the selection of the burner and the exercise of options herein:

a. This specification can be used for replacement or conversion installations to specify the procurement requirements for the burner. However, it should remain the responsibility of the contractor who is performing the boiler modifications to make the retrofitted boiler operate satisfactorily (see 3.1).

b. Fungus resistant varnish conforming to MIL-V-173 should be used to coat electrical components and circuit element, including terminal and circuit connections, when the burner is to be installed in humid conditions. Components and elements inherently inert to fungi or in hermetically sealed enclosures or current-carrying contact surfaces should not be coated.

c. Electromagnetic interference suppression (EMI), when required, should conform to the EMI suppression requirements and test limits for Class C3, Group I equipment as specified in MIL-STD-461. The burner should be subjected to test to determine conformance in accordance with MIL-STD-462.

The performance requirements specified herein may be based on other fuels providing the quantity on-site is sufficient for testing specified in section 4, and a guaranteed ultimate analysis and higher heat content are made available at the time of testing the burners. Corrections between the values of the analysis in section 3 of this specification and the guaranteed analysis and heating value should be made in accordance with the Hydronics Institute Testing and Rating Standard for Heating Boilers. Referenced below are some of the most commonly used fuels with their average specific gravity and higher heat content:

Average Average higher Fuel specific gravity heat content Natural gas 0.65 1,075 Btu/cu ft (40 054 kj/m³) Manufactured gases 0.38 535 Btu/cu ft (19 934 kj/m³) Mixed gas 0.50 800 Btu/cu ft (29 807 kj/m³) Liquefied petroleum gas 1.55 2,500 Btu/cu ft (93 148 k)/m³)