Static Electricity Values of Work Clothes Under Different Conditions
The Generation and Hazards of Static Electricity in Work Clothes: During normal work, workers frequently come into contact with external impurities (such as work surfaces, chair surfaces, tools, and equipment), and even their shoes rub against the ground while walking. This frequent contact, separation, and friction causes 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 clothing can lead to static induction, causing the skin to become charged as well, also forming a static voltage. Therefore, for workers, there are two possible discharge paths: one is discharge between the fingertips (skin) and a grounded conductor, and the other is discharge between the work clothes and a grounded conductor. Both types of discharge can damage static-sensitive devices. While anti-static 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 pay attention to eliminating static electricity on the skin, neglecting or not giving enough importance to eliminating static electricity in clothing, which needs improvement.
The following are the measured ranges of static voltage on clothing when the operator performs different actions:
**Charging Method**
**Static Voltage on Clothing (V)**
Walking on a normal cement floor in leather shoes (at normal speed)
1200~1500
Walking on a normal cement floor in plastic slippers (at normal speed)
2500~2600
Working at a desk on a synthetic rubber workbench
750~2000
Slightly rocking on a synthetic leather armchair
1500~280 0. Sliding on a synthetic leather upholstered chair
1500~2800 Suddenly standing up from a chair
3800~4500 Removing outer clothing
As can be seen from the above, the static voltage value on clothing during various human activities greatly exceeds the electrostatic discharge damage threshold of many static-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%; 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.