The main difference between Type 2 and Type 4 safety light curtains lies in their level of protection, reliability, and performance standards. Both are designed to safeguard operators working near dangerous machinery, but Type 4 light curtains provide a higher level of safety integrity and are used in more hazardous applications, while Type 2 devices are suitable for lower-risk environments.
A Type 2 safety light curtain follows IEC 61496-1 and IEC 61496-2 standards and is typically rated for Performance Level PL c or SIL 1. It detects an interruption in its infrared light beams and stops the machine, but it offers less redundancy and diagnostic coverage. Type 2 models are ideal for applications where the risk of injury is low, such as small pick-and-place machines, assembly benches, or semi-automatic equipment.
In contrast, a Type 4 safety light curtain provides higher reliability and failsafe design. It’s rated for Performance Level PL e or SIL 3, which means it includes dual microprocessors, self-checking circuits, and continuous monitoring. Even if one part fails, the system still operates safely. Type 4 curtains are used in high-risk applications like metal presses, robotic cells, and packaging lines where serious injury could occur.
In simple words, Type 2 = basic safety for low-risk tasks, while Type 4 = advanced safety for high-risk machinery. Type 4 light curtains meet stricter safety requirements and are mandatory where Category 4 or PL e protection is needed. So, when choosing between them, always evaluate the machine’s risk level — for any critical or hazardous operation, Type 4 safety is the correct and industry-standard choice.