74 which leads to a line 76 the outlet of pump 14 communicates with the head space of tank 12 via the line 76 line 64 features manually operated valve 75 and pneumatically operated valve 77 line 74 includes manually operated valve 82 and pneumatically operated valve 84 line 76 includes pneumatically operated valve 86 during off loading these valves are all opened in contrast valves 42 46 and 48 are closed as a result sump 16 does not receive lng from tank 12 and the outlet of pump 14 is isolated from the dispensing or saturation portion of the station instead lng flows from delivery tank truck 52 to sump 16 via hose 58 and line 64 and is pumped by pump 14 through line 76 to dispensing station tank 12 as a result tank 12 is refilled vapor from the head space of station tank 12 returns to the delivery truck tank via line 76 line 74 and hose 62 to relive pressure build up in the tank 12 prior to activation of pump 14 as illustrated in fig1 line 64 features a check valve 92 which prevents lng from flowing back towards the delivery truck as a result lng spills are prevented in the event that valves 75 and 77 are open when the feed hose 58 is not attached to connector 66 such a situation could occur if there was an error or failure in the valve control system or if the delivery truck driver.