40 CFR Appendix Table 31 to Subpart G of Part 63, Typical Number of Vacuum Breakers, NF6 and Roof Drains, a NF7

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Table 31 to Subpart G of Part 63 - Typical Number of Vacuum Breakers, NF6 and Roof Drains, a NF7
Tank diameter D (feet) b No. of vacuum breakers, NF6 No. of roof drains, N F7 double-deck roof c
Pontoon roof Double-deck roof
50 1 1 1
100 1 1 1
150 2 2 2
200 3 2 3
250 4 3 5
300 5 3 7
350 6 4 d
400 7 4 d

a This table should not supersede information based on actual tank data.

b If the actual diameter is between the diameters listed, the closest diameter listed should be used. If the actual diameter is midway between the diameters listed, the next larger diameter should be used.

c 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.

d For tanks more than 300 feet in diameter, actual tank data or the manufacturer's recommendations may be needed for the number of roof drains.

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United States Code

Title 40 published on 2015-08-22

The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 40 CFR Part 63 after this date.

  • 2017-01-18; vol. 82 # 11 - Wednesday, January 18, 2017
    1. 82 FR 5401 - National Emission Standards for Hazardous Air Pollutants: Ferroalloys Production
      GPO FDSys XML | Text
      ENVIRONMENTAL PROTECTION AGENCY
      Final rule; notice of final action on reconsideration.
      This final action is effective on January 18, 2017. The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of January 18, 2017.
      40 CFR Part 63

Title 40 published on 2015-08-22.

The following are only the Rules published in the Federal Register after the published date of Title 40.

For a complete list of all Rules, Proposed Rules, and Notices view the Rulemaking tab.

  • 2017-01-18; vol. 82 # 11 - Wednesday, January 18, 2017
    1. 82 FR 5401 - National Emission Standards for Hazardous Air Pollutants: Ferroalloys Production
      GPO FDSys: XML | Text
      ENVIRONMENTAL PROTECTION AGENCY
      Final rule; notice of final action on reconsideration.
      This final action is effective on January 18, 2017. The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of January 18, 2017.
      40 CFR Part 63