The PBL is a Blocking Device for Light Curtain Safety



Blocking Device for Prevention of Unexpected Restart (Video)



Safety Light Curtains – Photoelectric Sensors – Light Barriers – Perimeter Access Control

Safety light curtains are designed to protect personnel when operating in close proximity to hazardous machinery.

They are reliable, easy to install, cost-effective and enable a convenient and intelligent environment for easy personnel access.

However, when entering a light curtain guarded space, protection against unexpected restart cannot always be guaranteed.

How can I protect personnel from machinery restarting unexpectedly?



Mechanical Blocking Device for Personnel Protection

Photoelectric – Blocking – Device

Installation to Light Curtain

The blocking device is mounted beside the safety light curtain or light barrier

Deactivation in Normal Operation

When access is required, the light curtain is deactivated

Key Extraction

The personnel key is extracted; rotating the blocking plate

Prevention of Unexpected Restart

The light curtain beam is blocked preventing machine start up


Two-padlock lock out

Proactive Inhibit Functions


Proactive inhibit functions are a risk reduction measure to prevent start-up whilst performing whole body access into a safeguarded space (ANSI B11. 19-2019). There are a number of preventative measures which can be implemented for safeguarded spaces to prevent unexpected restart of hazardous machinery, however some are not always practicable.

Preventative Measures

Preventative Measures

Type 2 Body Protection (EN/IEC 61496-1/-2)   |   Single Beam   |   Type 4 Body Protection (EN/IEC 61496-1/-2)

The Fortress Photo-Electric or Light Curtain Blocking Device






Common Configurations


PBL2A-1-1-CLSL-MP1   |  PBL4A-1-1-CLSL-MP1  |
PBL2A-1-1-CLSL-MP3   |  PBL4A-1-1-CLSL-MP3 |
PBL2A-3-1-CLSL-MP3    |  PBL4A3-1-CLSL-MP3

Where are our devices used?


              Packaging Technologies                Robotics              Food and Beverage Manufacture


   Pharmaceuticals                Automotive Production               Conveyor Systems

Is the Light Curtain Blocking Device compatible with My Light Curtain?


The world of safety light curtains and light barriers is expansive. This is why Fortress have designed our blocking device with every eventuality in mind.

Installation Orientations   |   Light Curtain Dimensions   |   Detection Resolution   |
Light Curtain Guards and Coverings   |   Muting   |   Washdown   |   Offset Mounting