The BOC Polarstream in-transit refrigeration system may be integrated into road vehicles or freight containers. This system is shown schematically in Figure 5. It uses liquid nitrogen in the cooling process, which vaporises as it is released into the container reducing the temperature uniformly. The liquid nitrogen is stored in tanks connected to a spray bar that runs the length of the vehicle. A pneumatically powered temperature controller responds to sensors located throughout the vehicle to maintain the required temperature.