1 The freezer time shown is for best quality only â foods kept constantly frozen at 0Â° F will keep safe indefinitely.  How long does baked ham last at room temperature? Bacteria grow rapidly at temperatures between 40 Â°F and 140 Â°F; baked ham should be discarded if left for more than 2 hours at room temperature.
Using this to calculate theoretical water-chilling capacity: 1 ton of refrigeration (12,000 BTUs per hour) will chill. 12,000 lbs. water/fish 1Â°F in 1 hour. Theoretically, then, a sample application to chill seawater and fish: 40 tons refrigeration (480,000 BTUs per hour) will chill. 120,000 lbs. water/fish 20Â°F in 5 hours.
Therefore: 1 Refrigeration Ton = 2000 Pounds x 144 BTU per Pound / 24 hours = 12,000 BTU's per Hour The idea of Refrigeration Ton made it easier to sell equipment. The machine's capability could be compared to a quantity of ice.elting ice at 32 degrees Fahrenheit requires 144 BTU's per pound to become liquid at 32 degrees Fahrenheit. The Refrigeration Ton was defined as the heat absorbed by one ton of ice (2000 pounds) causing it to melt completely by the end of one day (24 hours).