A Mud Logging Unit was in the final phase of rig up when an explosion and fire occurred. The gas analyzers had been calibrated and the Flame Ionization Detection (FID) and Total Hydrocarbon Analyzer (THA) modules were left operating to stabilize while the outside sample points and drains were hooked up. This Mud Logging Unit used FID instrumentation that required hydrogen gas to be piped into the unit. The hydrogen gas was used as the fuel for the flame within the instrumentation. An explosion completely destroyed the unit.