---
kind: "section"
citation: "49 C.F.R. § 173.337"
title: "49"
number: "173.337"
heading: "Nitric oxide."
url: "https://uscodex.org/cfr/49/173.337"
---

# §173.337. Nitric oxide.

- (a) Nitric oxide must be packaged in cylinders conforming to the requirements of [§ 173.40](/cfr/49/173.40.md) and as follows:
  - (1) **DOT specification cylinder.** In a DOT 3A1800, 3AA1800, 3E1800, or 3AL1800 cylinder. A DOT specification cylinder must be charged to a pressure of not more than 5,170 kPa (750 psi) at 21 °C (70 °F). Transportation of nitric oxide in a DOT 3AL is cylinder is authorized only by highway and rail.
  - (2) **UN cylinder.** In a UN cylinder with a minimum test pressure of 200 bar. The maximum working pressure of the cylinder must not exceed 50 bar. The pressure in the cylinder at 65 °C (149 °F) may not exceed the test pressure. The use of UN tubes and MEGCs is not authorized.
  - (3) **Valves.** Cylinders must be equipped with a stainless steel valve and valve seat that will not deteriorate in contact with nitric oxide. Cylinders or valves may not be equipped with pressure relief devices of any type.
- (b) Each UN cylinder must be cleaned in accordance with the requirements of ISO 11621 (IBR, see [§ 171.7](/cfr/49/171.7.md) of this subchapter). Each DOT specification cylinder must be cleaned in compliance with the requirements of GSA Federal Specification RR-C-901D, paragraphs 3.3.1 and 3.3.2 (IBR, see [§ 171.7](/cfr/49/171.7.md) of this subchapter). Cleaning agents equivalent to those specified in Federal Specification RR-C-901D may be used; however, any cleaning agent must not be capable of reacting with oxygen. One cylinder selected at random from a group of 200 or fewer and cleaned at the same time must be tested for oil contamination in accordance with Federal Specification RR-C-901D paragraph 4.3.2 and meet the standard of cleanliness specified therein.

## Notes

### Amendments

[71 FR 33885, June 12, 2006]

### Authority

Authority: 49 U.S.C. 5101-5128, 44701; 49 CFR 1.81, 1.96 and 1.97.

### Amendments

[71 FR 33885, June 12, 2006]