The photoelectric switch is the abbreviation of the photoelectric proximity switch. It utilizes the shielding or reflection of the light beam by the detected object, and the circuit is connected by the synchronization loop to detect the presence of the object. The object is not limited to metal, all objects that can reflect light (or block light) can be detected. Photoelectric Proximity Sensor,Photoelectric Switch Sensor,Photoelectric Proximity Switch,Infrared Photoelectric Switch Sensor Changchun Guangxing Sensing Technology Co.LTD , https://www.gx-encoder.com
As the information transmission channel between buildings, the connection and transmission media of various types of IT equipment, integrated wiring is the starting point in the construction of infrastructure, and it is also the top priority of building fire protection facilities. On the other hand, with the rise of data centers, people are paying more and more attention to data security and resisting the catastrophic destruction of data brought about by the fire. This has also become an important task for data center integrated cabling.
Based on the significance of the integrated wiring fire protection performance, all cable product production, sales and use must undergo strict fire performance certification. According to the flame-retardant characteristics of the cable itself, the CO2 generated during combustion, the heat released, the density of the smoke, and the toxicity of the gas, there are currently many levels and standards for the fire protection of the cable.
In general, fire-retardant flame-retardant cables mainly include the UL series of the United States and the IEC 60332 series of international standards. The so-called "flame-retardant" refers to the characteristic that after the combustion, the flame spreads only within a limited range and self-extinguishes. Cables complying with UL standards have higher flame retardant performance and lower flame spread. They have the ability to prevent or delay the occurrence or spread of flames, avoid further equipment and property loss, and increase the time for personnel and data transfer.
Specific to UL series flame-retardant cables, according to test methods and indicators are divided into different levels, the safety standards include: UL 910 (ie, CMP level, air supply combustion test), UL 1666 (CMR level, upright combustion test), UL 1581 (CM/CMG grade, vertical burning test), UL 1581 vw-1 (CMX home grade, upright burning).
Among them, UL910 is the most demanding of the fire protection standards. The experiment stipulates that a plurality of samples be laid on the horizontal air duct of the device. The qualification standard is that the flame cannot be extended to the gas at the specified combustion temperature and time of the Bunsen burner. The front of the flame of the lamp is 5 feet away. The peak value of the optical density is 0.5 at the maximum, and the maximum value of the average density is 0.15.
This air supply combustion test is used for flame propagation and smoke concentration testing of space-borne cables and cables in the air environment. Cables that pass this test are considered to be flame-retardant grade cables suitable for use in plenum spaces. In other words, CMP grade cables are the highest grade and best flame-retardant cables in the UL series.