Abstract: A chemical storage facility, dispensing area, or equivalent unit is provided with a safety interlock device which automatically regulates access to the inlet used to introduce materials into the unit responsive to markings provided on the containers which hold such materials. In connection with the handling of potentially hazardous chemicals, such regulation is performed responsive to information provided on labeling associated with the bottles which contain the chemicals to be used. A bar code scanner is used to read bar-coded information provided on the labels affixed to the bottles, and the access door of the chemical storage facility or dispensing area is released, allowing the door to be opened, only in cases where the bar-coded information read by the scanner is found to correspond with the proper chemical to be dispensed.