Roof Fitting Loss Factors, K Fa , K Fb , and m, a and Typical Number of Fittings, N T

Fitting type and construction details Loss factors b Typical number of fittings, N T K Fa (lb-mole/yr) K Fb (lb-mole/[mi/hr] m -yr) m (dimensionless) Access hatch (24-in-diameter well) 1. Bolted cover, gasketed 0 0 c 0 Unbolted cover, ungasketed 2.7 7.1 1.0 Unbolted cover, gasketed 2.9 0.41 1.0 Unslotted guide-pole well (8-in-diameter unslotted pole, 21-in-diameter well) 1. Ungasketed sliding cover 0 67 c 0.98 Gasketed sliding cover 0 3.0 1.4 Slotted guide-pole/sample well (8-in-diameter unslotted pole, 21-in-diameter well) ( d ). Ungasketed sliding cover, without float 0 310 1.2 Ungasketed sliding cover, with float 0 29 2.0 Gasketed sliding cover, without float 0 260 1.2 Gasketed sliding cover, with float 0 8.5 1.4 Gauge-float well (20-inch diameter) 1. Unbolted cover, ungasketed 2.3 5.9 c 1.0 Unbolted cover, gasketed 2.4 0.34 1.0 Bolted cover, gasketed 0 0 0 Gauge-hatch/sample well (8-inch diameter) 1. Weighted mechanical actuation, gasketed 0.95 0.14 c 1.0 Weighted mechanical actuation, ungasketed 0.91 2.4 1.0 Vacuum breaker (10-in-diameter well) N F6 (Table 31). Weighted mechanical actuation, gasketed 1.2 0.17 c 1.0 Weighted mechanical actuation, ungasketed 1.2 3.0 1.0 Roof drain (3-in-diameter) N F7 (Table 31). Open 0 7.0 e 1.4 N F8 (Table 32 f ). 90 percent closed 0.51 0.81 1.0 Roof leg (3-in-diameter) N F8 (Table 32 f ). Adjustable, pontoon area 1.5 0.20 c 1.0 Adjustable, center area 0.25 0.067 c 1.0 Adjustable, double-deck roofs 0.25 0.067 1.0 Fixed 0 0 0 Roof leg (2 1 ⁄ 2 -in-diameter) N F8 (Table 32 f ). Adjustable, pontoon area 1.7 0 0 Adjustable, center area 0.41 0 0 Adjustable, double-deck roofs 0.41 0 0 Fixed 0 0 0 Rim vent (6-in-diameter) 1 g . Weighted mechanical actuation, gasketed 0.71 0.10 c 1.0 Weighted mechanical actuation, ungasketed 0.68 1.8 1.0 a The roof fitting loss factors, K Fa , K Fb , and m, may only be used for wind speeds from 2 to 15 miles per hour. b Unit abbreviations are as follows: lb = pound; mi = miles; hr = hour; yr = year. c If no specific information is available, this value can be assumed to represent the most common or typical roof fittings currently in use. d A slotted guide-pole/sample well is an optional fitting and is not typically used. e Roof drains that drain excess rainwater into the product are not used on pontoon floating roofs. They are, however, used on double-deck floating roofs and are typically left open. f The most common roof leg diameter is 3 inches. The loss factors for 2 1 ⁄ 2 -inch diameter roof legs are provided for use if this smaller size roof is used on a particular floating roof. g Rim vents are used only with mechanical-shoe primary seals.