R016600x

SECTION IV - FUEL SYSTEM

4.1 GENERAL Clayton steam generators are designed to fire on natural gas, propane, or fuel oils (ranging from No. 2 distillate light oil to No. 6 residual heavy oil). A standard combination burner is designed to support both gas and oil firing. This burner can remain installed when switching between gas and oil firing. Char- acteristics of, and installation guidelines for, both gas and oil fuel systems are described in detail in the following paragraphs.

NOTE The installing contractors are responsible for ensuring that all piping and fit- tings are rated for the intended system installation (material type, thickness, pressure, temperature). The installing contractors are also responsible for en- suring the steam system design meets the flow and pressure requirements of a Clayton steam generator (see Section VI, Table 1).

4.2 NATURAL GAS The Clayton gas train on modulating steam generators is designed and built in accordance with UL (Underwriters Laboratories), IRI (Industrial Risk Insurers), and FM (Factory Mutual) guidelines. It consists of a “double block-and-bleed” valve arrangement with proof-of-closure switches in both safety shut off gas valves. High and low gas pressure switches (with manual reset) are also provided. Unless otherwise stated (liquid petroleum and other gas operation requires engineering evalua- tion), the standard Clayton gas burner is designed for operation using pipe line quality natural gas. Gas supply connection sizes and rated gas flows for each model are provided in Tables 1and 2 of Section VI. The gas supply line must be sized to provide both the supply pressure and full rated flow indicated in Table 1 of Section VI without “sagging” (pressure drop). The gas supply pressure must not vary more than + 5% of Clayton’s required supply pressure. All gas supply connections must include a 12-inch drip leg immediately before the gas train. Pressure regulation is required if supply pressures are expected to exceed the 10 psi (0.69 bar) supply pressure limit. Regulators should be sized to pass 25% excess gas at full open position with mini- mal pressure drop.

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04/22/2015

Sect04_FuelSys_xx4_f.fm