Maintains that modern ammonia systems can be built to give higher efficiency and better safety. These improvements can also be applied to further improve the performance and safety of existing ammonia systems by replacing the high-charge pump circulation systems that are currently the standard, with low-charge systems designed to overfeed the evaporators without the use of pumps. Describes design safety measures for ammonia systems and explains ways of using ammonia that are most efficient. Considers in addition ammonia defrosting systems. Describes some ammonia system applications for water chilling, brine chilling, CO₂/ammonia cascade systems and ammonia cold store systems.