Napier equation

Kf, = correction for Napier equation =1.0 when P[ = 1515 psig = (0.1906P, - 1000)/ (0.2292Pi - 1061) where Pj > 1515 psia and < 3215 psia, Table 7-6. Ksb = superheat correcUon factor, see Table 7-7. For saturated steam at any pressure, Ksb =1.0 Pb = stamped bursting pressure, psia... 

Kf = correction factor for the Napier equation = 1 when Pj < 10,339 kPaA... 

Relieving pressure, = 1100 1.1 + 101 = 1311 kPaA Correction factor for Napier equation, = 1... 

Forveiy thin hquids, Eqs. (14-206) and (14-207) are expected to be vahd up to a gas-flow Reynolds number of 200 (Valentin, op. cit., p. 8). For liquid viscosities up to 100 cP, Datta, Napier, and Newitt [Trans. In.st. Chem. Eng., 28, 14 (1950)] and Siems and Kauffman [Chem. Eng. Sci, 5, 127 (1956)] have shown that liquid viscosity has veiy little effec t on the bubble volume, but Davidson and Schuler [Trans. Instn. Chem. Eng., 38, 144 (I960)] and Krishnamiirthi et al. [Ind. Eng. Chem. Fundam., 7, 549 (1968)] have shown that bubble size increases considerably over that predic ted by Eq. (14-206) for hquid viscosities above 1000 cP. In fac t, Davidson et al. (op. cit.) found that their data agreed veiy well with a theoretical equation obtained by equating the buoyant force to drag based on Stokes law and the velocity of the bubble equator at break-off ... 

The high pressure steam correction factor Kn is used when the steam pressure Pi is greater than 1500psia [ 10,340 kPaa] and up to 3200 psia [22,060 kPaa]. This factor has been adopted by ASME to account for the deviation between steam flow as determined by Napier s equation and actual saturated steam flow at high pressures. Kn can also be calculated by the following equation or may be taken from Figure F. 1. 

The equation for steam service is a modification of Napier steam flow given in the ASME Boiler and Pressure Vessel Code. ASME Power Boiler Code applications permit 3 percent overpressure. The equation for steam relief is [12] ... 

Equation (3.60) assumes that all radiation arises from a single point and is received by an object perpendicular to this. This view factor must only be applied to the total heat output, not to the flux. Other view factors based on specific shapes (i.e., cylinders) require the use of thermal flux and are dimensionless. The point source view factor provides a reasonable estimate of received flux at distances far from the flame. At closer distances, more rigorous formulas or tables are given by Hamilton and Morgan (1952), Crocker and Napier (1986), and TNO (1979). 

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