ATEX certified R+W safety couplings were supplied by RR Fisher & Co Ltd for particle measuring systems manufactured by Sympatec. The safety couplings featured an ATEX design with a high temperature steel plug segment.
Sympatec builds particle measuring systems that are designed to detect particles from the nano range up to a size of 10mm. These systems find application in quality assurance in cement production, pharmaceutical manufacturing, print toner manufacturing and coffee production among others.
Before measurements can be made, a representative sample is taken from the production system. The materials to be tested are conveyed on air through the production process in pipes with an inside diameter of 50mm - 800mm.
The consistency of the material to be tested may vary depending on its position within the pipe. In order to ensure representative test results, a small sampling tube is placed inside the main pipe. This sampling tube has a spiral shape and is put into combined rotary and linear motion so that sample is taken from the entire flow of material.
An R+W safety coupling of type SK5/10/F/XX was used in the sampling tube’s drive mechanism. This coupling has ATEX certification for zones 1/21 and 2/22. This is necessary because samples are taken in an explosive atmosphere or ignitable dust.
In addition to installation and operating instructions, an ATEX certificate and required declaration of conformity are also enclosed with the coupling when it is delivered.
The SK5 pluggable solution was specified by the customer. This is necessary for specific industrial environments where different products are often produced on the same equipment line.
When converting the line for production of a different product, the components used to process the previous product must be cleaned. Plug-in capability makes it easy to remove components for cleaning.
Another problem that presented itself at this stage involved the temperature range. The operating temperature range specified for the ATEX certified coupling is up to 150ºC.
Since standard plastic plug-in segments are only rated for use up to 120ºC, the material for these parts was changed. The new steel plug design can handle the extended temperature range and is built similar to the plastic part.