With compressed-air machines which discharge the cold air direct into the insulated room or hold, a snow box is provided close to the outlet of the expansion cylinder to catch the snow and congealed oil.
In such compressed-air machines as are now made there is no injection of water during compression, and the compressed air is cooled in a surface cooler, not by actual mixture with a shower of cold water.
Among the new manufactories were a shipbuilding establishment at Groton near New London, which undertook contracts for the United States government, and a compressed-air plant near Norwich.
In some instances electric motors have been substituted for compressed-air engines in such machines.
Compressed-air Machines.-A compressed-air refrigerating machine consists in its simplest form of three essential parts -a compressor, a compressed-air cooler, and an expansion cylinder.