ABSTRACT
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Historical Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 normal-Propyl Bromide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Cleaning Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Plastics and Elastomers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Drums and Drum Linings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Thermal Stability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Hydrolytic Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Comparison of nPB Properties with Other New Cleaning Solvents . . . . . . . . . . . . . . . . . 121 Special Formulations-Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Compatibility with Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Compatibility with Plastics and Elastomers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Removal of Ionic Residues from Integrated Circuit Boards. . . . . . . . . . . . . . . . . . . 122 Prevention of Silver Tarnish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Health, Safety, Environmental, and Regulatory Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Toxicology-Acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Mammalian Genetic Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Mammalian Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Aquatic Acute Toxicology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Recommended Exposure Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Environmental and Health Regulatory Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Environmental and Health-Related Parameters Compared with Other
New Solvents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Case Histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
1. Electronic Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 2. Electric Motor Stators and Refrigeration Coils . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
3. Implantable Body Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 4. Aluminum Parts for Optical Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 5. High-Performance Inertial Navigation Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 129
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
INTRODUCTION
The cleaning of complex parts to exacting specifications has become a major consideration in the manufacture of a wide variety of machines, appliances, and instruments. The introduction of chlorinated solvents provided manufacturers and fabricators a convenient and economical way to clean a host of difficult soils contaminating strategic parts. Efficient cleaning, rapid drying, low flammability, residue-free parts, and relatively low solvent costs all contributed to the popularity of chlorocarbon and hydrochlorocarbon fluids. However, many chlorine-containing solvents have now been banned or restricted because of environmental and/or health considerations. With the mandated elimination of the most popular cleaning solvents, many manufacturers switched to aqueous or semiaqueous cleaning systems. Although these proved to be viable solutions in many applications, they were not suitable for all situations. In the search to find more appropriate alternatives, a wide variety of new solvents were developed.1 Many of the new solvent cleaners do excellent jobs, but still suffer from one or more deficiencies relative to the overall cost/performance of the chlorinated materials they replaced. Some of the newer solvents, such as some hydrochlorofluorocarbons (HCFCs), have been shown to have environmental problems and either have been banned from use in cleaning applications or are scheduled for phaseout. In other cases, the newly introduced solvents meet the environmental and toxicological requirements, but do not meet the performance standards. The need in specialized applications for a high-performance cleaning agent that could be used in a safe and efficient manner led to the development of cleaning systems based on the solvent normalpropyl bromide (nPB).
