Local distribution vehicles are used for final delivery to the retail or catering outlet. They are usually engaged in multi-delivery work which involves frequent door openings.
In this case, air temperature measurement may not give a representative indication of product temperature and therefore automatic temperature monitoring equipment is not a mandatory requirement.
However, it is necessary to fit at least a vehicle temperature gauge or thermometer which has sensors located such that they indicate the temperature of the return air. If an automatic air temperature monitor is used on a local delivery vehicle, it is useful to increase the time response of the system by ‘damping’ the sensors in tubes of glycerol or editable oil to smooth out the wide variations in temperature caused by the frequent door openings.
Alternatively a “between pack” probe may be connected to the recording device. This probe is normally installed in the last load to be delivered by the vehicle to provide an indication or worst case product temperature.