# Vents.

**Citation:** 49 CFR 193.2431  
**Type / status:** regulation / historical  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** 1999-10-01  
**Published:** Not stated

(a) Hazardous fluids may not be relieved into the atmosphere of a building or other confined space.

(b) Boiloff vents for hazardous fluids may not draw in air during operation.

(c) Venting of natural gas/vapor under operational control which could produce a hazardous gas atmosphere must be directe

## Document text

(a) Hazardous fluids may not be relieved into the atmosphere of a building or other confined space.

(b) Boiloff vents for hazardous fluids may not draw in air during operation.

(c) Venting of natural gas/vapor under operational control which could produce a hazardous gas atmosphere must be directed to a flare stack or heat exchanger in order to raise its temperature to achieve positive buoyancy and safe venting.

[45 FR 9203, Feb. 11, 1980, as amended by Amdt. 193-2, 45 FR 70404, Oct. 23, 1980]

## Provenance

- Official: Yes
- Source: <https://www.govinfo.gov/app/details/CFR-1999-title49-vol3/CFR-1999-title49-vol3-sec193-2431>
- Source ID: `govinfo-cfr`
- SHA-256: `69f01fde13bdc343feacd4c9d6cefaf755563df102e6296c3e8ee5486c818621`
- Retrieved: 2026-08-12T01:41:23.231Z
- Exported: 2026-08-25T02:54:36.617Z
- Document slug: `49-cfr-193-2431`

### Source metadata

```json
{
  "part": "193",
  "section": "193.2431",
  "subpart": "Subpart E—Equipment",
  "annualEdition": 1999,
  "revisedAsOf": "1999-10-01",
  "govInfoPackage": "CFR-1999-title49-vol3",
  "legalStatus": "official-annual-cfr-edition",
  "effectiveDateNote": null,
  "historicalAnchor": true,
  "historicalAnchorNote": "The section appears in an official annual CFR edition but is absent from the connected current eCFR corpus.",
  "jurisdiction": "US"
}
```