Selecting a Safety Edge

When selecting a safety edge it is essential to check that it has enough overtravel for your application. Customer's often assume any safety edge is better than none, but this is not true. If the machine or gate's overtravel distance is greater than the safety edge profile then it will offer little or more likely no protection.

Selecting the correct safety edge for your application Bircher provides the following calculation model to help you with your selection. To select the suitable safety edge as it is important to establish the stopping and overtravel distances in order to guarantee the greatest possible safety for your system.

Calculation of the stopping distance of hazardous parts (s1):

s1 = ½ × v × T

Where:

v = Speed of the hazardous movement [mm/s] T = Run-on time of the entire system (machine + safety edge) [seconds]

Calculation of the minimum overtravel of the safety edge s:

s = s1 × C

Where:

C = Safety factor, at least 1.2 (a greater safety factor should be selected if there are other factors such as a brake system which might be damaged ref EN1760-2)

The safety edge should have an overtravel figure greater than or equal to s.