- One ton of refrigeration equals the removal of 12,000 Btu/h of heat.
- CAt various temperature levels; 0 to 50°F, use chilled brine and glycol solutions; -50 to 40°F, ammonia, Freons, butane; -150 to -50°F, ethane or propane.
- In single stage compression, the compression ratio is limited to about 4.
- In multistage compression, economy is improved with interstage flashing and recycling, ie: economiser operation.
- Absorption-refrigeration (employing ammonia to -30°F, lithium bromide to 45°F) is economical when waste steam is available at 12 psig or so.