Diverted and extinguished
New Atex solution: blower certified as an “ignition source capture” unit

A simple, ingenious solution eliminates the need for spark arresters which cause pressure and energy loses on rotary piston blowers. The secret lies in the fact that the muffler does not have the usual absorption material, which is flammable and not suitable for use with food products.

The regulations which apply to Atex applications are becoming increasingly stringent in many industries, particularly rules relating to pneumatic conveyance of bulk goods, and this affects machine manufacturers. High-pressure pneumatic systems, which are often used in Zones 22 and 21 where dust is present, present a special challenge for process engineers. The blowers are not necessarily exposed to an explosive zone, but the requirements normally apply to any pipes which are attached. Due to the design, the mechanical generation of sparks resulting from faults can not be completely excluded. A spark created in this way could reach pipes which contain a potentially explosive mixture of gas or dust. Elaborate, expensive spark arresters are often installed to avoid the risk of explosion.

Aerzener has taken this challenge head on, and the company has come up with a solution which has been certified by TÜV Nord. The solution makes use of the Delta blower base, which also acts as a muffler.
Sparks, which were artificially generated during testing, were allowed to flow through the base for several minutes. Results showed that the sparks were “captured” by internal deflectors and ultimately extinguished.
The secret is in the muffler
This design eliminates the need for additional spark arresters. The secret lies in the fact that the muffler does not have the usual absorption material, which is flammable and not suitable for use with food products.
Aerzener blowers with nominal widths between DN 50 and DN 250 have now been certified. A total of 16 sizes are available in the Delta blower range which offers suction volumes flows of 30 m3/h to 15,000 m3/h, pressure up to 1000 mbar and vacuum up to 500 mbar. Mechanical drive is another positive design feature of the compact blower. It eliminates the significant incremental cost of motors with Atex explosion protection which are used on separate blowers that have electrical drive. The Aerzener design eliminates the need for modifications which may have to be made to the acoustic hood to install a blower with explosion protection and/or modifications to the terminal box. The company has also developed a new filter for pneumatic suction systems, which acts as a zone separator and is approved for Zones 21 and 22.
The filter, which has special “cages”, is puncture-proof and is able to filter out any particles to avoid the formation of an explosive mixture in the blower. There is no need for the external filters which would otherwise have to be used, and this also reduces investment costs.