Conversion ratios reported for the Sandia National Laboratories intermediate-scale (FITS-B series) steam explosion experiments have been examined and recalculated. It is shown that these conversion ratios corresponding to the work done to compress the chamber air, ηD, may have been overestimated by as much as a factor of 8.3. The recalculated values of ηD range from 0.05 to 1.04% compared with reported values of 0.2 to 8.6%. The corresponding maximum value for the total fraction of melt thermal energy converted to both kinetic energy and compression work, ηtot = ηKE + ηD, is 2.34% compared to a reported value of 9.9%.