HSEs investigation into a gasoline overfill of a carbon adsorption VRU revealed concerns with its design. The overfill prevention system was not independent of the basic process control system (BPCS), meaning that when the BPCS failed, the overfill prevention system also failed, resulting in a loss of containment. This risked a significant fire and explosion, as well as extensive environmental damage. Duty holders should follow a safe system of work to assess the risk of overfill, check equipment and where appropriate modify VRU control systems and/or implement independent control measures. | 
