Rapid Discharge Accumulators
Accumulators required to satisfy their functional fluid demand in less than 3 min. This includes dedicated shear (both surface and subsea), dead man systems, autoshear accumulators, some acoustic and special purpose accumulators.
Source: API SPEC 16D, Specification for Control Systems for Drilling Well Control Equipment and Control Systems for Diverter Equipment, Upstream Segment, Second Edition, July 2004. Global Standards