This study examines the factors that may cause systematic errors in the manometric
temperature measurement (MTM) procedure used to evaluate product temperature during
primary drying. MTM was conducted during primary drying using different vial loads, and the
MTM product temperatures were compared with temperatures directly measured by
thermocouples. To clarify the impact of freeze-drying load on MTM product temperatures,
simulation of the MTM vapor pressure rise was performed, and the results were compared …

This article evaluates the procedures for determining the vial heat transfer coefficient and the
extent of primary drying through manometric temperature measurement (MTM). The vial heat
transfer coefficients (K v) were calculated from the MTM-determined temperature and
resistance and compared with K v values determined by a gravimetric method. The
differences between the MTM vial heat transfer coefficients and the gravimetric values are
large at low shelf temperature but smaller when higher shelf temperatures were used. The …

The purpose of this work was to study the factors that may cause systematic errors in the
manometric temperature measurement (MTM) procedure used to determine product dry-
layer resistance to vapor flow. Product temperature and dry-layer resistance were obtained
using MTM software installed on a laboratory freeze-dryer. The MTM resistance values were
compared with the resistance values obtained using the “vial method.” The product dry-layer
resistances obtained by MTM, assuming fixed temperature difference (ΔT; 2° C), were lower …