After many years of passive autocatalytic recombiner (PAR) experimentation and analytical investigations, there are still gaps in the understanding of PAR behavior. For instance, PAR performance under severe accident conditions including issues related to low oxygen content, presence of carbon monoxide, and reactive or nonreactive aerosols still require examination. Following the closure of the large-scale hydrogen test facilities at AECL's Whiteshell Laboratories (WL), a new Hydrogen Safety Test Facility (HSTF) has been commissioned at Chalk River Laboratories (CRL) to continue the efforts to understand PARs and their operation in various accident scenarios. The HSTF is a spherical pressure vessel with an internal volume of 0.25 m3. This paper presents the experiments performed at the HSTF, investigating the scaling of a PAR under varying concentrations of H2, and steam as well as the effects of initial gas temperature and pressure. The experimental data from the HSTF (0.25 m3) will be compared with the data obtained in the large-scale facilities (6.6 m3 and 60 m3) to establish a scaling factor for the HSTF with a reasonable fit over the range of conditions tested.