Nederman FlexPAK 1000 DX, User Manual, Page: 26 / 545

FlexPAK 800/1000 DX EN
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3.3 Explosion protection
The CE and ATEX markings on this unit ensure both a high level of safety and protection against
ignition of the collected combustible dust. However, if an explosion occurs due to misuse,
insufficient maintenance or faulty installation, this unit is equipped with additional protection
methods to avoid dangerous pressure build-up in the filter.
FlexPAK 800/1000 DX is equipped with one of the following protection systems.
•
Explosion venting, see figure 2A.
•
Explosion suppression system, see figure 2B.
•
Flameless venting.
3.3.1 Explosion venting
The harmful effects of an explosion are minimized by venting the pressure and flame of the
explosion through an explosion relief panel, see figure 2A. In case of an explosion, the resulting
flame and pressure escape through the explosion relief panel which is to be directed towards a safe
area without any people. This area is referred to as the ‘risk area’.
The risk area is to be clearly marked, for example with a fence, warning lines and signs, and entry
is prohibited when the filter is in operation. The area is to be free of any flammable or combustible
material or other objects which may be damaged by the flames and explosion pressure.
The general size of the risk area is shown in figure 3. The following dimensions apply:
•
A = 10 m (32.8 ft)
•
B = 5 m (16.4 ft)
NOTE!
The risk area may extend beyond the values given above. The final risk area is to be
evaluated with regards to affecting factors found in Standard EN 14491.
NOTE!
For assistance and information, contact Nederman.
3.3.2 Explosion suppression system
With an explosion suppression system, the early stage of an explosion is detected with optical and/
or pressure-sensitive devices, and an extinguishing agent is quickly dispersed into the filter, see
figure 2B. The suppression of the explosion is initiated an extremely short time after detection of
the explosion (in milliseconds), and stops the pressure rising and extinguishes (suppresses) the
flames of the explosion.
This ensures that the filter is not stressed to a dangerous level by the explosion.
The key components of the explosion suppression system are the following:
•
An explosion detection device (optical/pressure-sensitive).
•
A computer-operated control unit.
•
Action elements such as pressure cylinders containing an extinguish agent with an extra fast
opening valve.
Detailed information regarding system installation, function, operation and maintenance can be
found in the suppression system manual.
3.3.3 Flameless venting
The method of flameless venting is similar to method 1 “explosion venting”. However, a device
attached to the outside of the vent will stop flames from exiting the filter vessel. Such a device is
sometimes referred to as a “quench-device” or “flameless-device”.
Common for all types of flameless devices is that the explosion is released through a specially
designed grid or mesh. The grid or mesh will allow pressure from an explosion to be released, but
prevent the explosion’s flames from exiting outside the filter vessel.
The benefit of using a flameless vent device is that it reduces the size of the risk area. This
increases the possibility of positioning the FlexPAK 800/1000 DX closer to manned areas or
equipment.