{"operation":"document","citation":"PI-92-0105","title":"U.S. Department of Transportation, Pipeline Safety Regulatory Programs, DPS-1 — Pipeline Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"1992-07-02","effective_on":null,"summary":"PI-92-0105 response to U.S. Department of Transportation, Pipeline Safety Regulatory Programs, DPS-1 concerning 192.187.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-92-0105.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-92-0105.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-pi-92-0105","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1992/g92_07_02_Sanders_192.187_Xs.pdf","body":"<<<PAGE 1>>>\n\nPI-92-0105\nJuly 2, 1992\nINFORMATION: Section 192.187\nCesar De Leon, Director\nPipeline Safety Regulatory Programs, DPS-1\nRichard Sanders, Manager\nPipeline Safety Division, DTI-60\nBy memo of June 17, 1992, you asked me to explain the difference between the sizes of areas for ventilation under\nparagraphs (a) and (c) of § 192.187. The difference is explained as follows: Ventilation under paragraph (a) is by means\nof two ducts that extend aboveground. Differential pressure forces vault gases through the ducts; so only small openings\nare needed for proper ventilation. Under paragraph (c), ventilation is by means of surface openings in the vault. This\nmethod requires a large open area, because ventilation is accomplished by dispersion, or mixing of vault gases with the\nair above the vault.\n\n<<<PAGE 2>>>\n\nMemorandum\nU.S. Department of Transportation\nResearch and\nSpecial Programs Administration\nSubject: ACTION: Part 192.187, Vented Vaults\nFrom: Richard Sanders\nManager, Pipeline Safety Division, DTI-60\nTo: Cesar DeLeon\nDirector, DPS-10\nOn April 20, 1992, Mr. Alex Dankanich of the Maryland Public Service Commission contacted Mr. Jack Edwards of our\noffice to discuss a concern about the sizing requirements for vents on vaults per Part 192.187. The sections of concern\nare:\nPart 192.187 Vaults: Sealing, venting and ventilation.\nEach underground vault or closed top pit containing either a pressure regulating or reducing station, or a pressure\nlimiting or relieving station, must be sealed, vented or ventilated, as follows:\n(a) When the internal volume exceeds 200 cubic feet:\n(1) The vault or pit must be ventilated with two ducts, each having at least the ventilating effect of a pipe 4 inches in\ndiameter.\n(b) When the internal volume is more than 75 cubic feet but less than 200 cubic feet:\n(3) If the vault or pit is ventilated, paragraph (a) or (c) of this section applies.\n(c) If a vault or pit covered by paragraph (b) of this section is ventilated by openings in the covers or grating and the\nratio of the internal volume, in cubic feet, to the effective ventilating area of the cover or grating, in square feet, is less\nthan 20 to 1, no additional ventilation is required.\nThe mathematics works out to require 25 square inches of effective ventilating area for a vault greater than 200 cubic\nfeet per Part 192.187(a)(1).\nVentilated vaults under Part 192.187(b)(3), for vaults greater than 75 cubic feet, but less than 200 cubic feet, require a\nminimum effective ventilating area as illustrated below:\nVAULT SIZE MINIMUM VENT AREA\n76 cubic feet 3.8 square feet or 547 square inches\n100 cubic feet 5.0 square feet or 720 square inches\n199 cubic feet 9.9 square feet or 1,433 square inches\n\n<<<PAGE 3>>>\n\nIt is difficult to justify that a smaller vault requires considerably more effective ventilating area.\nI would appreciate an opinion on the reason for this seeming discrepancy in the code. Thank you for the assistance.","truncated":false,"body_characters":2953}