12. Some useful facts about water and ice

Properties of water and ice

 Properties Metric Units Remarks Pure water Density at 15°C 1 kg/l 1 t/m³ Pure water becomes denser as the temperature falls, until at 4°C it is at its densest, ie 1 kg/l. For practical ice-making calculations, the density of water can safely be assumed to be 1 kg.1 Specific heat 1.0 kcal/kg°C Latent heat of fusion 80 kcal/kg Thermal conductivity (at 10°C) 0.5 kcal/mh°C Freezing point 0°C Boiling point 100°C
 Sea water Density 1.027 kg/l At 0°C and salinity of 3.5%. 1.027 t/m³ Specific heat 0.94 kcal/kg°C At 0°C 0.93 kcal/kg°C At 20°C Latent heat of fusion 77-80 kcal/kg Approximate values at salinities of up to 3.5%. Indeterminate owing to presence of salts. Freezing point at salinity of: Salinity varies from sea to sea but for practical purposes the world average of 3.5% is sufficiently accurate. 1.0% -0.6°C 2.0% -1.2°C 3.0% -1.6°C 3.5% -1.9°C 4.0% -2.2°C
 Ice Density Freshwater ice 0.92 kg/l At 0°C 0.92 t/m³ Seawater ice 0.86-0.92 t/m³ Depending on salinity and amount of trapped air. Specific heat: For calculating the amount of ice to use on fish, a value of 0.5 is sufficiently accurate. Specific heat of seawater ice can be very much higher near to melting point. 0°C 0.49 -20°C 0.46 Latent heat of melting 80 kcal/kg Thermal conductivity: kcal/mh°C 0°C 1.91 -10°C 1.99 -20°C 2.08 Melting point 0°C Melting point of seawater ice is indeterminate, since salt content is rarely uniform throughout the ice, but should on average be about -2°C. Stowage rates m³/t Block ice in blocks 1.4 Crushed block ice 1.4-1.5 Flake ice 2.2-2.3 Tube ice 1.6-2.0 Plate ice 1.7-1.8