---
kind: "section"
citation: "30 C.F.R. § 250.459"
title: "30"
number: "250.459"
heading: "What are the safety requirements for drilling fluid-handling areas?"
url: "https://uscodex.org/cfr/30/250.459"
---

# §250.459. What are the safety requirements for drilling fluid-handling areas?


You must classify drilling fluid-handling areas according to API Recommended Practice 500 (incorporated by reference, see [§ 250.198](/cfr/30/250.198.md)); or API Recommended Practice 505 (incorporated by reference, see [§ 250.198](/cfr/30/250.198.md)). In areas where dangerous concentrations of combustible gas may accumulate, you must install and maintain a ventilation system and gas monitors. Drilling fluid-handling areas must have the following safety equipment:

- (a) A ventilation system capable of replacing the air once every 5 minutes or 1.0 cubic feet of air-volume flow per minute, per square foot of area, whichever is greater. In addition:
  - (1) If natural means provide adequate ventilation, then a mechanical ventilation system is not necessary;
  - (2) If a mechanical system does not run continuously, then it must activate when gas detectors indicate the presence of 1 percent or more of combustible gas by volume; and
  - (3) If discharges from a mechanical ventilation system may be hazardous, then you must maintain the drilling fluid-handling area at a negative pressure. You must protect the negative pressure area by using at least one of the following: a pressure-sensitive alarm, open-door alarms on each access to the area, automatic door-closing devices, air locks, or other devices approved by the District Manager;
- (b) **Gas detectors and alarms except in open areas where adequate ventilation is provided by natural means.** You must test and recalibrate gas detectors quarterly. No more than 90 days may elapse between tests;
- (c) **Explosion-proof or pressurized electrical equipment to prevent the ignition of explosive gases.** Where you use air for pressuring equipment, you must locate the air intake outside of and as far as practicable from hazardous areas; and
- (d) **Alarms that activate when the mechanical ventilation system fails.**

## Notes

### Amendments

[76 FR 64462, Oct. 18, 2011, as amended at 91 FR 35351, June 10, 2026]

### Authority

Authority: 30 U.S.C. 1751, 31 U.S.C. 9701, 33 U.S.C. 1321(j)(1)(C), 43 U.S.C. 1334.

### Source

Source: 76 FR 64462, Oct. 18, 2011, unless otherwise noted.

### Amendments

[76 FR 64462, Oct. 18, 2011, as amended at 91 FR 35351, June 10, 2026]