Ask the Experts

We are building a system that has an inspection area with a knee wall and inner and outer light curtains. The inner curtains are muted unless the outer curtains are broken, then the inner curtains are active. The standard states that in this Point of Operation walk through situation, presence must be continually sensed in the area. We have used Line of Sight in the past meaning someone would have to intentionally reset the outer curtains while being able to see if someone was in the point of operation area. Is this acceptable or do we need to use a mat or horizontal curtains to continuously monitor the area?

Administrative controls can be effective but have you exhausted potential safeguarding approaches? Would an interlocked gate be better, or is access too frequent? If a light curtain is needed due to frequency of access, an authorized person who enters for inspection might be better protected by providing him with a key establishing supervisory control over the reset function. Of course that only works if the key is not left in the reset.

Lee Burk from Pilz Automation Safety L.P. | 02/10/2021

l.burk@pilzusa.com