Causes of Static Electricity

Causes of Static Electricity Brass, stainless steel Generation of static electricity on an object by Rubber rubbing is known as the triboelectric effect. The following is a list of substances in the triboelectic Acrylic series. The list is arranged in such an order that when Polystyrene foam any two substances in the list contact one another and then separate, the substance higher on the list assumes Polyurethane foam a positive charge. Acetate Glass Human hair Nylon Wool Fur Aluminum Polyester Paper Cotton Wood Steel Acetate fiber Saran Polyethylene Polypropylene PVC (vinyl) KEL F Teflon^® The size of an electrostatic charge on two different materials is proportional to the separation of the two materials. Electrostatic voltage levels generated by nonconductors can be extremely high. However, air will slowly dissipate the charge to a nearby conductor or ground. The more moisture in the air, the faster a charge will dissipate. Table 10-1 shows typical measured charges generated by personnel in a manufacturing facility. Note the decrease in generated voltage with the increase in Nickel, copper, silver humidity levels of the surrounding air. Table 10-1.-Typical Measured Electrostatic Voltages VOLTAGE LEVELS @ RELATIVE HUMIDITY MEANS OF STATIC GENERATION LOW 10-20% HIGH 65-90% WALKING ACROSS CARPET 35,000 1,500 WALKING OVER VINYL FLOOR 12,000 250 WORKER AT BENCH 6,000 100 VINYL ENVELOPES FOR WORK 7,000 600 INSTRUCTIONS COMMON POLY BAG PICKED UP FROM 20,000 1,200 BENCH WORK CHAIR PADDED WITH URETHANE 18,000 1,500 FOAM 10-16