Static Electricity Values of Antistatic Workwear Under Different Conditions
The Generation and Hazards of Static Electricity in Antistatic Workwear: During normal work, workers frequently come into contact with external impurities (such as work surfaces, chair surfaces, tools, and equipment), and even the soles of their shoes contact the ground while walking. Frequent contact, separation, and friction cause clothing and shoes to become charged, eventually forming a static voltage on the clothing when equilibrium is reached.
Of course, since the human body is a good conductor, the charge on the clothing can cause the skin to become charged due to electrostatic induction, also forming a static voltage. Therefore, for the worker, there are two possible discharge paths: one is the discharge between the fingertips (skin) and a grounded conductor, and the other is the discharge between the workwear and a grounded conductor. Both types of discharge can damage static-sensitive devices. While antistatic wrist straps can eliminate the first type of discharge hazard, they cannot eliminate the second. This is because wrist straps can only eliminate static electricity on the human skin, which is a good conductor, and cannot dissipate static electricity from the more insulating clothing.
People often only focus on eliminating static electricity from human skin, while neglecting or not giving enough attention to eliminating static electricity from clothing, which needs improvement.
The following are the measured ranges of static voltage on clothing during different operator actions:
Electrification Method | Static Voltage on Clothing (V)
Walking on ordinary cement floor in leather shoes (normal speed) | 1200~1500
Walking on ordinary cement floor in plastic slippers (normal speed) | 2500~2600
Working at a desk on a synthetic rubber workbench | 750~2000
Slightly swaying on an artificial leather chair | 1500~2800
Sliding on an artificial leather chair | 1500~2800
Suddenly standing up from a chair | 3800~4500
Removing outer clothing As can be seen from the above, the static voltage on clothing during various activities greatly exceeds the electrostatic discharge damage threshold of many electrostatic sensitive devices. Therefore, touching or approaching these devices may cause damage. It should also be noted that the common belief that wearing pure cotton work clothes prevents the accumulation of static electricity and is therefore safe is a one-sided view.
This is generally true only when the relative humidity is above 50%; however, when the relative humidity is relatively low, the charge on pure cotton products increases significantly. Experiments show that when the relative humidity is below 30%, the charge on pure cotton fabrics is comparable to that of polyester; and when the relative humidity is below 20%, the charge on cotton fabrics can even be higher than that of some synthetic fiber fabrics.