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Table 30 to Subpart G of Part 63—Roof Fitting Loss Factors, K<sub>Fa</sub>, K<sub>Fb</sub>, and m, <sup>a</sup> and Typical Number of Fittings, N<sub>T</sub>

Roof Fitting Loss Factors, K<sub>Fa</sub>, K<sub>Fb</sub>, and m, <sup>a</sup> and Typical Number of Fittings, N<sub>T</sub>

  1. CFR
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  3. Title 40
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  5. Chapter I
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  7. Part 63
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  9. Subpart G
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  11. Appendix Table 30 to Subpart G of Part 63
CorpusDaily eCFR
Displayed edition2026-04-27
Last updated2026-04-27

Table 30 to Subpart G of Part 63—Roof Fitting Loss Factors, KFa, KFb, and m, a and Typical Number of Fittings, NT

Fitting type and construction detailsLoss factors bTypical number of fittings, NT
KFa (lb-mole/yr)KFb (lb-mole/[mi/hr]m-yr)m (dimensionless)
Access hatch (24-in-diameter well)1.
Bolted cover, gasketed00c 0
Unbolted cover, ungasketed2.77.11.0
Unbolted cover, gasketed2.90.411.0
Unslotted guide-pole well (8-in-diameter unslotted pole, 21-in-diameter well)1.
Ungasketed sliding cover067c 0.98
Gasketed sliding cover03.01.4
Slotted guide-pole/sample well (8-in-diameter unslotted pole, 21-in-diameter well)(d).
Ungasketed sliding cover, without float03101.2
Ungasketed sliding cover, with float0292.0
Gasketed sliding cover, without float02601.2
Gasketed sliding cover, with float08.51.4
Gauge-float well (20-inch diameter)1.
Unbolted cover, ungasketed2.35.9c 1.0
Unbolted cover, gasketed2.40.341.0
Bolted cover, gasketed000
Gauge-hatch/sample well (8-inch diameter)1.
Weighted mechanical actuation, gasketed0.950.14c 1.0
Weighted mechanical actuation, ungasketed0.912.41.0
Vacuum breaker (10-in-diameter well)NF6 (Table 31).
Weighted mechanical actuation, gasketed1.20.17c 1.0
Weighted mechanical actuation, ungasketed1.23.01.0
Roof drain (3-in-diameter)NF7 (Table 31).
Open07.0e 1.4NF8 (Table 32 f).
90 percent closed0.510.811.0
Roof leg (3-in-diameter)NF8 (Table 32 f).
Adjustable, pontoon area1.50.20c 1.0
Adjustable, center area0.250.067c 1.0
Adjustable, double-deck roofs0.250.0671.0
Fixed000
Roof leg (21⁄2-in-diameter)NF8 (Table 32 f).
Adjustable, pontoon area1.700
Adjustable, center area0.4100
Adjustable, double-deck roofs0.4100
Fixed000
Rim vent (6-in-diameter)1 g.
Weighted mechanical actuation, gasketed0.710.10c 1.0
Weighted mechanical actuation, ungasketed0.681.81.0
a 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.