N.Y. Comp. Codes R. & Regs. tit. 12, § 14-9.4
Safety valve requirements.
(a) Each boiler shall have at least one safety valve and if it has more than 500 square feet of bare tube water heating surface, or if an electric boiler has a power input more than 1,100 kw, it shall have two or more safety valves or safety relief valves. For a boiler with combined bare tube and extended water-heating surface exceeding 500 square feet, two or more safety valves or safety relief valves are required only if the design steam generating capacity of the boiler exceeds 4000 lb/hr. The method of computing the steam-generating capacity of the boiler is given as follows:
The maximum quantity of fuel C that can be burned per hour at the time of maximum forcing is determined by a test. The maximum number of heat units per hour, or CH, is then determined, using the values of H given in the Table below. The weight of steam generated per hour is found by the formula:
W =C × H/1100 × 0.75
where
W = weight of steam generated/hr, lb
C = total weight or volume of fuel burned/hr at time of maximum forcing, lb or cu ft
H = heat of combustion of fuel, Btu/lb or Btu/cu ft (See Table below)
The sum ot the safety valve capacities marked on the valves shall be equal to or greater than W.
For the purpose of checking the safety valve capacity, the following values of heats of combustion of various fuels may be used:
H = Btu/lb Semibituminous coal 14,500 Anthracite 13,700 Screenings 12,500 Coke 13,500 Wood, hard or soft, kiln dried 7,700 Wood, hard or soft, air dried 6,200 Wood shavings 6,400 Peat, air dried, 25% moisture 7,500 Lignite 10,000 Kerosene 20,000 Petroleum, crude oil, Pennsylvania 20,700 Petroleum, crude oil, Texas 18,500 Municipal solid waste 7,800 H = Btu/cu ft Natural gas 960 Blast-furnace gas 100 Producer gas 150 Water gas, uncarbureted 290 - (b) Organic fluid vaporizer generators require special consideration as given in the ASME Code.