20:37-20:47 Empty reference cell run, Run # 3816 Pressure = -15 psig 20:48 Fill reference cell with 140 psig of N2 20:49-20:54 N2 reference cell run with 140 psig, Run # 3817 Pressure = 140 psig at start During run pressure increased to 141 psig 21:01 Vent and evacuate reference cell