HEAT STORAGE COMPOSITIONS

摘要

The stability of heat storage compositions comprising tetrasodium pyrophosphate is increased by raising the pH or the composition to at least 10.6. The increase in pH is preferably achieved by adding sodium hydroxide or more preferably an alkali metal orthosphosphate to the composition. The preferred additive is trisodium orthophosphate, The preferred pyrophosphates are those which comprise less than 1% by weight of tripolyphosphates. These compositions are novel and may conveniently be produced by calcination of a mixture comprising disodium hydrogen orthophosphate and trisodium orthophosphate.