Ignition of combustible materials will happen more readily in the presence of nitrous oxide. This is why the Department of Transportation (DOT) requires that cylinders containing nitrous oxide, meet the following requirement listed in the “Code of Federal Regulations” (CFR-49) section 173.304 “Charging of Cylinders with liquefied Compressed Gas” paragraph (a)(4)(ii);
Each cylinder must be cleaned in compliance with the requirements of Federal Specification RR-C-901c paragraph 3.7.2 and 3.8.2. Cleaning agents equivalent to those specified in RR-C-901c 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 less cleaned at the same time must be tested for oil contamination in accordance with Specification RR-C-901c paragraph 22.214.171.124 and meet the standard of cleanliness specified.
Cylinders manufactured by Catalina Cylinders for nitrous oxide service are cleaned and tested in accordance with RR-C-901-c at the time of manufacture. Cylinders that are manufactured for charges or fills other than oxygen and nitrous oxide have not been cleaned for oxygen or nitrous oxide service.
Conversion of cylinders not cleaned for oxygen or nitrous oxide service can be done but is not recommended by Catalina Cylinders. If such cylinders are to be converted to nitrous oxide service, the cylinders must be cleaned as if for oxygen service prior to filling with nitrous oxide.
Also, all cylinder accessories (i.e. valves, regulators, etc.) that will come into contact with the nitrous oxide charge must be compatible with oxygen and cleaned as if for oxygen service. The Compressed Gas Association (CGA) has two publications, pamphlet G-4.1 “Cleaning Equipment For Oxygen Service” and a directory “Directory of Cleaning Agents for Oxygen Service” that we recommend if such cleaning is to be done. Please note that after all cleaning operations it is recommended that the cylinder be dried completely to reduce the chance of corrosion from occurring.