Table 30 - Roof Fitting Loss Factors, KFa, KFb, and m,a and Typical Number of Fittings, NT

Fitting type and construction detailsLoss factorsbKFa (lb-mole/yr)KFb (lb-mole/[mi/hr]m-yr)m (dimensionless)Typical number of fittings, NTAccess hatch (24-in-diameter well)1.Bolted cover, gasketed00c 0Unbolted cover, ungasketed2.77.11.0Unbolted cover, gasketed2.90.411.0Unslotted guide-pole well (8-in-diameter unslotted pole, 21-in-diameter well)1.Ungasketed sliding cover067c 0.98Gasketed sliding cover03.01.4Slotted guide-pole/sample well (8-in-diameter unslotted pole, 21-in-diameter well)(d).Ungasketed sliding cover, without float03101.2Ungasketed sliding cover, with float0292.0Gasketed sliding cover, without float02601.2Gasketed sliding cover, with float08.51.4Gauge-float well (20-inch diameter)1.Unbolted cover, ungasketed2.35.9c 1.0Unbolted cover, gasketed2.40.341.0Bolted cover, gasketed000Gauge-hatch/sample well (8-inch diameter)1.Weighted mechanical actuation, gasketed0.950.14c 1.0Weighted mechanical actuation, ungasketed0.912.41.0Vacuum breaker (10-in-diameter well)NF6 (Table 31).Weighted mechanical actuation, gasketed1.20.17c 1.0Weighted mechanical actuation, ungasketed1.23.01.0Roof drain (3-in-diameter)NF7 (Table 31).Open07.0e 1.4NF8 (Table 32 f).90 percent closed0.510.811.0Roof leg (3-in-diameter)NF8 (Table 32 f).Adjustable, pontoon area1.50.20c 1.0Adjustable, center area0.250.067c 1.0Adjustable, double-deck roofs0.250.0671.0Fixed000Roof leg (21/2-in-diameter)NF8 (Table 32 f).Adjustable, pontoon area1.700Adjustable, center area0.4100Adjustable, double-deck roofs0.4100Fixed000Rim vent (6-in-diameter)1 g.Weighted mechanical actuation, gasketed0.710.10c 1.0Weighted mechanical actuation, ungasketed0.681.81.0a The roof fitting loss factors, KFa, KFb, 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 21/2-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.