Model Number

Type C, Type D

Segregation procedures of the moving product particles during filling and emptying produce static electricity. When the FIBC is filled, the electric charge accumulates inside the FIBC on top of the product and may create a high electric field, that an ignitable discharge is possible. When filling and emptying the FIBC with a bulk product, a combustible dust arises inside the FIBC. Thus when filling and emptying the FIBC in hazardous areas with explosive atmospheres, a reliable protection against the risk of electrostatically induced ignitions is essential. Ünsa offers the entire range of protective measures for the safe handling of FIBCs in hazardous areas.

ÜNSA TYPE C

The dissipative Ünsa Type C FIBC which forms a reliable interconnected grid enclosing a maximum non-conductive area of 25 cm². (e.g. 45 mm. mesh size) The FIBC has a resistance to ground at all points at the outside of R<10⁸Ω . The breakdown voltage of the coated and uncoated fabric does not exceed 6 kV.

When filling and emptying, the Type C FIBC must be grounded. For the safe operation of the plant, Ünsa recommends double secured grounding via the conductive grounding tab and the conductive lifting loops.

The Type C FIBC can be fitted with a conductive inner liner. The conductive inner liner is in contact with the ground via the interwoven conducting filaments of the fabric and should not be removed from the FIBC in hazardous areas.

ÜNSA TYPE D

Under the trade name "HCD-Fabric®" Ünsa has developed a
High Corona Discharge Fabric. The Ünsa Type D FIBC made out of
HCD-Fabric® is certified by Wolfson Institute and Swiss Institute according to the IEC 61340-4-4 Standard. Ünsa Type D FIBC with
HCD-Fabric® is protected under patents in Europe, USA, Japan and Australia.

The accredited electrostatic test laboratory of Ünsa has been established to carry out the below tests on FIBCs:

• Gas ignition
• Electrical breakdown voltage
• Electrical resistance
• Charge transfer

These test results are used for evaluating the electrostatic properties of FIBCs to be used in hazardous explosive atmospheres or for quality control purposes.

The laboratory can be conditioned between 60% RH and 20% RH, and 23°C via dehumidifier and air condition systems. All metal support frameworks, working platforms and any other conductors, including operators, within one meter of the tested FIBC are earthed, regardless of the FIBC being tested.

The tests are carried out according to IEC 61340-4-4 Standards. At least 200 ignition attempts on the test FIBC are made. The whole sequence of ignition attempts is made on each of the four walls of the test FIBC (50 ignition attempts on each wall). Additional attempts are made on any panel attached to the FIBC. After completing the ignition attempt no ignition should occur on the test FIBC. The tests are carried out with ethylene and enriched air mixture having a MIE of 0,14 mJ.