Static electricity poses a significant hazard in the chemical industry. Processes such as filling, dispensing, conveying, and tipping flammable powders can generate static charge, potentially leading to ignition. To mitigate these risks, hazardous materials must be stored and transported using appropriately designed chemical storage bags.
Static Discharge
Many common powders accumulate static charge, even when they themselves are chemically inert. For instance, Polytetrafluoroethylene (PTFE), Polyethylene, and Poly(methyl methacrylate) (PMMA) are all very familiar, inert polymers. However, they rapidly build a negative electrical charge if they come into contact with metals. Dusts and powders have a static Capacitance of 102 Farads, whilst the human body, in comparison, has a Capacitance of around 100 picofarads (pF).
This is the small electrical shock that we sometimes experience when touching metal objects. While humans may experience an unpleasant shock due to capacitance, improperly transported or stored chemical powders pose a far greater risk. These substances can trigger a hazardous chain reaction, ultimately leading to a dangerous and potentially deadly explosion.
IEC 63140-4-4
The Type specifications for chemical storage anti-static bulk bags are outlined in IEC 61340-4-4. This assesses chemical contents on their Minimum Ignition Energy (MIE) and specifies the appropriate FIBC type based on the risk of ignition. Categorisation is dependent upon the materials used, the anti-static qualities, and elements such as human error. There are two different types of anti-static bulk bags suitable for environments where there may be an atmosphere with explosive dust, gas and vapour: Type C and Type D. These FIBC anti-static bulk bags are highly versatile and can be used for transporting and storing a wide range of chemicals, from resins to fine powders.
Type C
Type C FIBCs are made from a conductive polypropylene fabric woven with grounded conductive threads. Designed for storing dust contents with a Minimum Ignition Energy (MIE) of < 3 mJ - including resins, titanium dioxide (TiO2), and bisphenol A (BPA) - these FIBCs incorporate a weave of conductive tapes that ground the bag. Importantly, for their anti-static features to work effectively, Type C anti-static FIBC bags must be grounded when filling and discharging.
Type D
Type D FIBC bags incorporate all the benefits of Type C bags. However, the important difference is that anti-static Type D bulk bags do not require grounding. Instead, they are constructed from quasi-conductive yarns, which are naturally dissipative materials. This has two main benefits for the chemical industry as not only does it increases operational efficiency, but it also greatly reduces the risk of human error. It is essential to ensure that operators and surrounding equipment are properly grounded to maintain a safe environment. Type D bags offer flexibility and safety for handling flammable powders and chemicals.
Prioritise Safety With Cliffe Packaging
IEC 61340-4-4-compliant anti-static bulk bags are essential for ensuring safety and efficiency in chemical transport and storage and, when used correctly, they greatly minimise the risks associated with static electricity in hazardous environments.
For more information about our range of chemical storage bags, contact the team at Cliffe Packaging today!
