Cologne – Many applications even in hazardous areas require a fast LAN connection – for example for powerful INDUSTRIAL HMI systems that are to be integrated seamlessly into a company's IT system. Industrial optical fiber is usually the method of choice for networks, since it can cover greater distances than TP copper professional cables and resists electromagnetic forces. The safety of optical networks requires specific expertise, which is why specialists in explosion protection should be consulted. The explosion hazard inherent in light is frequently underestimated: as little as a few dozen or hundred milliwatt of light energy affecting a surface the size of a pencil-tip after a cable break, for example, can ignite an explosive gas atmosphere.

Optical signals must therefore comply with a suitable protection type when passing through hazardous areas. This requires certified transmitters and professional receivers of a special design. Usually, the signals are designed inherently safe, that is, they are of protection type "Ex op is", which is achieved by limiting irradiance. Special caution is necessary because typically, professional switches with optical outputs transmit close to or even above the permitted level of light emissivity. Additionally, a test certificate for switches and devices is essential for installation in zone 1. Under certain circumstances, alternative protection types may be protected optical radiation ("Ex op pr") or a safe error detection with interruption and blocking of the optical signal ("Ex op sh"). As a rule, a safe and acceptable solution for hazardous areas must neither exceed a certain irradiance (i.e. radiation at a surface per unit area) nor allow for the release of excessive light energy in absolute terms, regardless of dispersion. Due to years of experience in explosion protection, R. STAHL can support users when determining the relevant maximum values and, on request, can supply them with suitable solutions in the form of complete packages.