Sch 2 para 13 Provisions for filling and discharge
Where appropriate, the pressure equipment must be so designed and provided with accessories, or provision made for their fitting, as to ensure safe filling and discharge in particular with respect to risks such as— (a) on filling— (i) overfilling or overpressurisation having regard in particular to the filling ratio and to vapour pressure at the reference temperature; (ii) instability of the pressure equipment; (b) on discharge, the uncontrolled release of the pressurised fluid; (c) on filling or discharge, unsafe connection and disconnection.