Type C FIBCs refer to the class of FIBCs that actually protects against dangerous static discharges through grounding of the bag itself during the filling and discharging processes. These bags are safe when grounded because any electrostatic potential that builds up as a result of rapid filling or discharging quickly and safely exits the bag to ground via the network of conductive fibers woven into the fabric of the bag. This is true as long as the bag continually remains grounded.
How it Works
Type C FIBCs are constructed of fabrics with conductive carbon, silver core, or steel threads woven into them no more than a certain maximum allowable distance apart. These threads create a Faraday cage, therefore, when one part of the FIBC is connected to a grounding cable, or comes into contact with any other conductor that is grounded, the entire bag then becomes safely grounded.
Even though all of the product does not contact the conductive threads, the spacing of these threads is such that any isolated charge that develops on the surface of the bag is drawn toward the grounded threads, effectively neutralizing that charge. Once grounded, the bag technically cannot hold onto enough electrostatic energy to cause ignitions of a flammable environment.
Where & When It Works
Using Type C or Groundable FIBCs can be a very effective guard against incendive electrical discharges as long as the bags remain grounded during both filling and discharging of product. If the bag becomes ungrounded during either of these processes for any reason, it can create an extremely dangerous and explosive situation. Great care must be taken by operators to insure a positive ground is achieved and maintained before beginning to use the FIBC.
When used correctly and consistently, Type C bags can be used in nearly any flammable or combustible environment with very low MIEs (Minimum Ignition Energies). However, Procon Pacific recommends that you consult an expert to determine the most appropriate package for use in your particular environment.
Testing & Results
Testing of Type C bags is usually accomplished through a simple grounding detector that either lights up or beeps when a complete circuit is formed from the testing device to ground.
Type C Technology
Type C FIBC technology has been around for a long time and has its postive and negative aspects. It is very safe when used correctly. However, if ungrounded, the bag can be a much greater explosion hazard than a standard polypropylene FIBC and should be used with great care.
There are some companies who refuse to use anything else other than Type C FIBCs in their sensitive processes. For that reason, this is the most common type of FIBC for use in flammable and combustible environments. There is, and always will be a large demand, for these types of packages. If you desire to learn more about using Type C FIBCs, please contact us and we would be happy to consult with you on your specific situation.
Characteristics of Type C FIBCs
Conductive threads are interwoven throughout fabric
Grounding is required for effective use
Very safe when used properly
Can be very dangerous when left ungrounded during fill or discharge
Oldest and most common FIBC to mitigate static discharges in process
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