Abstract: There is disclosed a process and apparatus whereby typically furnished commercially nitrogen tetroxide propellants for rocket engines may be upgraded to decrease flow decay problems and to increase the shelf life of the product; thereby providing for longer duration trouble-free rocket engine performance. The raw MON material is initially converted if necessary to the "Red" type; dissolved iron salts and other dirt particulates are removed by cooling and filtering, and thenceforth throughout the process the material is filtered at each transfer operation. Specific apparatus arrangements are provided for facilitating the process and the end product is of increased purity; whereby upon being furnished to an engine for test or vehicle launching purposes the program may proceed as scheduled and the vehicle may be maintained in space for a longer period of time.

Abstract: A process is disclosed for cleaning and passivating stainless steel apparatus used in the manufacture, transport, storage and/or use of nitrogen oxides. The process involves sequentially treating stainless steel surfaces of apparatus which contact a nitrogen oxide, with various solutions, in such manner as to enable the apparatus to substantially maintain the quality of the nitrogen oxide to be manufactured, transported, stored and/or used therein. Thus, for example, the purity of nitrogen tetroxide, used as a propellant for rocket engines and the like, may be maintained longer, the shelf life significantly increased and rocket engine flow decay problems markedly reduced through use of the disclosed cleaning and passivating process.