Installation, Operation and Maintenance manual
12
Downflo
®
Evolution
By venting the explosion to the outside in a safe direction (outside), the pressure
inside the dust collector is limited such that it will not collapse. The vent area is
designed using:
• VDI 3673. Pressure Venting of Dust Explosions, VDI-Kommmision Reinhaltung
der Luft, July 1995.
• NFPA 68. Guide for Venting of Deflagrations, 1994 Edition.
• EN 14491. Dust explosion venting protective systems, March 2006.
• IChemE. Dust explosion prevention and protection, 2002.
The explosion panels are certified and provided with a device to detect its actual
opening up. This device should be used to stop the plant automatically by interlocking
and can be used to activate a sprinkler system to extinguish a fire following the
explosion.
By using vent ducts in case of indoor installation, the explosion is lead to the outside
and into a safe direction. Vent ducts, however, will increase the expected reduced
explosion pressure considerably. To prevent that the expected reduced explosion
pressure exceeds the design strength of your Donaldson Torit dust collector, the
maximum Kst value of your dust to be collected has to be considerably lower in case
of using vent ducts .
There also should be taken into account that, due to the venting explosion, the dust
collector is subjected to a reaction force.
Standard Donaldson Torit dust collectors are vented vertically and the reaction forces
will be directed downwards into the foundation of the dust collector: this causes no
hazards.
However, when the dust collector is side vented, the reaction forces also are directed
horizontally and may push the dust collector over if not secured well. Therefore in case
of horizontal vents the Donaldson Torit dust collectors should be specially secured.
See figure 5: Typical foundation anchor, page 17.
In case of side venting, the dust collector will have to be adequately supported
in order to cope with horizontal recoil forces. See figure 5: Typical foundation
anchor, page 17.
To prevent that the explosion runs back to connected equipment, a back-flap valve
or other explosion barriers should be installed.
To prevent propagation of fire, burning products or explosion from the hopper to the
outside or process, through the hopper outlet, either an explosion proof rotary valve
should be installed that automatically stops at explosion detection or an explosion
proof reception bin or other explosion proof dust discharge systems.
