Safety light curtains are safety devices designed to protect both potentially hazardous machinery and the individuals working with such machinery. One of the advantages of light curtains is their compact design and ease of use, compared to bulky mechanical guards.

What is a Safety Light Curtain?

Safety light curtains are essentially presence or motion sensors. They create a photoelectric light beam barrier between a transmitter and a receiver, which detects when an object breaches this light area. This allows them to detect potentially hazardous machine movements or human presence in areas where they shouldn’t be. By doing so, they add an extra layer of safety around potentially dangerous machinery.

Types of Safety Light Curtains

There are two types of safety light curtains, classified based on the scale of protection they provide:

• Point of Operation Control (POC) Safety Light Curtains: These curtains are designed to provide protection on a small scale, specifically protecting hands, fingers, and arms working near the machine. They are typically installed very close to the machine, directly where the operator interacts with it.

• Perimeter Access Control (PAC) Safety Light Curtains: PAC light curtains differ from POC types as they provide full-body protection. They create a barrier around machines that do not require close proximity by workers and are designed to detect people or objects entering the light barrier.

Both POC and PAC light curtains operate in the same manner. The primary difference is their size and scale, which makes them suitable for different applications.

Type 2 and Type 4 Light Curtains

Safety light curtains are not only divided into POC and PAC types but also into Type 2 and Type 4 groups. While these two types may appear similar, their differences are significant. Essentially, the difference between Type 2 and Type 4 light curtains lies in their design to meet different safety requirements.

Type 4 safety light curtains are necessary when the risk level is much higher and when adhering to higher safety standards. Type 2 safety light curtains, on the other hand, are designed for situations with relatively low risk. Therefore, they offer fewer safety features and cannot be used in situations where Type 4 light curtains are required.

Key Differences Between Type 2 and Type 4 Light Curtains

• Fault Detection: Type 4 light curtains are characterized by repetitive, automatic cross-checks for faults and errors. If a problem occurs, a Type 4 curtain will immediately detect it and send a signal to the machine to lock it down. The machine will remain inoperable until the affected part is inspected, possibly replaced, and the system is reset.

  Type 2 light curtains are not as sensitive. They perform periodic internal circuit tests without checking for faults or errors. This means that if an issue arises, it might not be detected until the second test, which does not render Type 2 light curtains ineffective but indicates they are suitable for lower risk scenarios.

• Protection Levels: Type 4 light curtains are available for body, hand, and finger protection. Type 2 light curtains offer fewer options and only provide hand and body protection, hence not offering the fine detail level required for finger protection.

In summary, Type 2 light curtains are a more cost-effective version of Type 4 light curtains. They have lower capacity and fewer safety protocols, making them a budget-friendly option for low-risk situations where Type 4 light curtains are not necessary.

Type 2 light curtains are suitable for scenarios where possible injuries are manageable with a basic first aid kit, while Type 4 light curtains are appropriate for situations with a significantly higher risk of injury.