For access panels or doors supporting an interlocking device allowing access to mechanical parts that move for periods after the energy source is removed, a separate mechanism to delay release of the retaining or locking mechanism may be incorporated.
A critical safety system is a safety control system responsible for ensuring the safety of a person when approaching or accessing a hazard. Failure of the critical safety system will leave a person exposed to the hazard, and in danger. Critical safety systems may include barriers or guards fitted to prevent access, or integrated complex interlocking and presence sensing systems.
Simultaneous two-handed operation. Where a machine has only one operator, the use of simultaneous two-handed operation buttons can serve as a risk control. This ensures that operation of the hazardous mechanism cannot occur until both hands are clear of the danger area.
Administrative controls, such as effective supervision, instruction and training, are required to ensure that only one key is available for the system, and the key is not removed from the access gate or guard by a second operator while a person is exposed to the danger area of the plant. Operations such as maintenance, repair, installation service or cleaning may require all energy sources to be isolated and locked out to avoid accidental start-up.