Recent studies indicate that dry-running cycloid-type screw compressors with variable rotor pitch may be very suitable for R718 (water) chillers and heat pumps. However, these studies are based on thermodynamic models rather than experimental data and there is currently no R718 screw compressor with variable rotor pitch available commercially. In this study, the performance of a screw spindle vacuum pump with variable rotor pitch is experimentally investigated for various inlet and outlet pressures below atmospheric pressure using air as a working fluid. The measured pressure range corresponds to saturated gas temperatures of R718 between 0 °C and 100 °C. The resulting performance map for air is used to estimate the potential performance with R718, using appropriate correction factors. The results are evaluated in regards to the potential of spindle screw compressors for future R718 chiller and heat pump applications.