Notes On The Evaluation and Avoidance of Electrostatic Charges

Notes On The Evaluation and Avoidance of Electrostatic Charges

Electrostatic charges can occur when two surfaces are rapidly separated, whereby at least one surface must be an insulator. Critical processes, for example, are pneumatic conveyors, Big Bag filling stations, or even silos with the danger of a conical pile discharge. In order to avoid electrostatic discharges at such FIBC filling stations, it is necessary to assess the bulk material and to select the proper FIBC Type.

How do electrostatic charges develop?

Electrostatic charges and the associated discharges are considered as one of the 13 possible ignition source types to be considered in a plant-related risk assessment. A distinction is made between the most varied types of discharge which, depending on the type, can be responsible for igniting gases or dusts (Table 1).

Electrostatic discharges and their ignition potential

* Fig. 1: Electrostatic discharges and their ignition potential. Source: www.bgrci.de

Selection of the suitable Big Bag

Big Bags, also referred to as FIBC´s, are divided into the types A, B, C, D, which can be categorized according to their protective characteristics as follows:
Avoid brush discharges: Type C and D
Avoid propagating brush discharges: Type B, C and D
Avoid spark discharges: Type B, C and D
Type C Big Bag has conductive filaments, which makes it necessary to ground type C Big Bag. Such grounding can be carried out by means of a cable and clamp. Another option is the grounding by means of a grounding monitoring system such as FARADO II FIBC. An approval function enables the Big Bag Type C to only be filled if the grounding is correctly established.