S. t. p. (or N. T. P. normal temperature and pressure) are the standards to which measurements of gases are referred, and are the pressure of a column of 760 mm of mercury (101 325 N/m2) and the temperature of 0°C (273° absolute)
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}