Final answer:
The primary eye wash should be used for immediate flushing until the victim reaches another safety unit.
Step-by-step explanation:
An eye wash or safety shower is used to remove chemicals or foreign objects from the eyes or body in case of an accident. Primary eye wash stations provide a controlled flow of water specifically designed for flushing the eyes, while drench showers are meant for full-body rinsing. Secondary eye wash stations may be used if the primary unit is not easily accessible, and tertiary wash stations are generally located outside the building for more severe emergencies.