Safety light curtains (also known as light guards or light curtains) are optical sensing devices. They provide flexibility, fast and frequent access to machines and better visibility. In addition, they are easier and more cost-effective to maintain than mechanical barriers. If you're in the market for a quality safety system, we're here to answer some of your burning questions.
How do safety light curtains work?
Light curtains come in pairs. They consist of a transmitter and a receiver that communicate via invisible light beams. These beams form a protective zone. In the event of damage, they send a stop signal to the machine safety control. The beams also pulse at a specific frequency. This way they do not interfere with other light sources and vice versa.
What is the difference between Type 2 and Type 4 safety light curtains?
Type 2 light curtains are usually the more economical choice. They are not as versatile as Type 4 light curtains. Choose Type 2 safety light curtains for hand and body protection in lower risk situations. type 2 safety light curtains are also an excellent choice for supplemental protection. Installing a secondary guard will prevent resetting the primary guard.
Type 4 light curtains are a larger investment. However, they do provide more safety and control. Choose Type 4 Safety Light Curtains for medium to high risk environments. "Type 4 light curtains offer a high level of fault tolerance through redundancy and monitoring. They meet OSHA regulations and ANSI control reliability standards" (Carlson).
To determine if a Type 2 or Type 4 light curtain is required, the engineer or designer must perform a complete risk assessment.
What are the advantages of safety light curtains over mechanical barriers?
Light curtains use a beam of light to detect when a person or object enters a hazardous area. Easy access to the machine increases efficiency if the machine operator needs to access the machine frequently. Safety light curtains also increase the visibility of the machine. In addition, minimal wear and tear makes them more cost-effective than mechanical barriers.
How do I know which resolution I need?
Resolution is the distance between two neighboring beams and the beam diameter. Light curtains with high resolution can detect fingers. Low resolution safety light curtains are great for detecting arms or entire people. Medium resolution is suitable for detecting the hand.
How do I calculate the proper spacing distance for a safety light curtain?
The proper spacing distance is unique to each situation. Factors to consider include: light curtain resolution, response time, machine and operator speed. The separation distance should allow enough time for the machine to stop before the operator comes into contact with the hazard. The following is a formula for calculating safety distances based on ANSI standards.
ANSI 安全距离公式
D s =K × (T s + T c + T r + T spm ) + D pf
K= 手速常数(63 英寸/秒)
T s = 机器的停止时间(用停止时间测量装置测量)
T c = 控制系统的响应时间
T r = 安全光幕的响应时间(由供应商提供)
T spm = 额外的停止时间以补偿正常的停止时间变化
D pf = 深度穿透系数
What do "auto reset" and "manual reset" mean?
Auto reset and manual reset are optional features. They modify the output signal switching device (OSSD) on the safety light curtain, which sends a stop signal to the machine controller.
The Auto Reset feature is useful when the operator needs to repeatedly reach or enter a guarded area. The OSSD sends a stop signal to the machine's safety controls when the operator crosses the guarded area. Once the operator retreats, the light curtain will resume normal operation.
For manual reset, the operator must press the reset button when the guarded area is unoccupied. This is useful for large protected areas. The operator can pass through the light curtain into the protected area. When he leaves the area, he resets the safety light curtain.
What's the difference between the fade and mute features?
Blanking and muting are optional safety light curtain features. The fade function ignores moving or stationary objects of a specific size. This is ideal for situations where part of the machine enters the protected area.
Silence allows objects or people to pass through the protected area, but only for the non-hazardous portion of the machine cycle. During this phase of the cycle, the entire light curtain is temporarily disabled. The shield also has the ability to allow only objects to pass through and not people.
Are there any precautions to be taken when installing?
Yes. When placing a light curtain near a reflective surface, one or more beams may reflect back. When this happens, the light curtain will not detect when an object passes through. This is more likely to happen with Type 2 light curtains because they have a larger effective aperture angle. Therefore, it is important to place the light curtain at a safe and appropriate distance from the reflecting surface.