The GPA TP-25 (LPG) was developed to support calculations from a basis of 60 degree Fahrenheit. Using tables 23E and 24E and following the logic of ASTM D 1250-04, procedure 11.1.7.3, QuantityWare has developed an enhancement to allow reliable usage of these tables for base temperatures of 15 and 20 degree Celsius. For more information, please send a mail to info@quantityware.com.