A measuring system alone cannot be considered as a safety accessory, as a safety accessory as defined in PED necessarily requires :
- a measuring or detection function and
- an activation function for correction, or shutdown, or shutdown and lockout.
In order for a control system to be classified as a safety accessory, it shall be designed and placed on the market as an ultimate means of protecting pressure equipment from exceeding allowable limits, and therefore it shall meet the corresponding essential requirements of Annex I, section 2.11.