Understanding ESD Smock Testing Procedures

 To test ESD smocks, measurement of the fabric’s static dissipative properties is done on Ohm's scale and ensures that it is properly grounded. This is crucial to prevent the smock from acting as an isolated floating conductor. To start with, we look at how ESD smocks are defined by industry standards and why preventing them from becoming isolated conductors is so important. 

 

ESD Resistance Requirements for Smocks 

ESD garments are classified into three categories according to industry standards: 

• Antistatic Clothing 

• Groundable Antistatic Clothing 

• Groundable Antistat Clothing Systems 

 

ESD Smock Requirements: For an item to be considered an ESD smock, it should have a surface resistivity of less than 1 x 10¹¹ ohms. 

 

Antistatic Clothing: Surface resistance is below 1 × 10^11 ohms when checked across the garment using the point-to-point method as shown in Figure 5 below. 

 

Place electrodes from the meter on both sleeve panels of the garment lying on an insulative surface to carry out this test and measure the resistance path between them. 

 

Groundable Antistatic Clothing: Surface resistance less than 1 x 10⁹ ohms measured point-to-point and point-to-groundable point. 

 

In place of one electrode of the sleeve panel used during point-to-groundable point testing, provide a ground connection instead. 

 

Groundable Antistat Clothing Systems: Surface resistance not exceeding 3.5 x10⁷ ohms measured with a man wearing the garment that has a wrist strap attached to it. 

 

It also agrees with recommendations regarding wrist strap resistance so that total system resistance (person, garment and grounding cord) falls to permitted limits. 

 

Isolated Floating Conductors 

The ESD smocks must be groundable, which is facilitated by the inclusion of conductive thread. The failure to electrically bond them properly to grounded surfaces such as floor mats, wrist straps or floors can cause these clothing to act as isolated floating conductors. 

 

This point is explicitly highlighted in industry guidelines that garments should always be bound to the wearer’s grounding system in order not to float. 

 

Importance of Grounding 

Static control is established on the grounding principle – the connection of electrically conductive and dissipative materials with ground equalizes electrostatic charges with respect to the earth's potential. When an item is grounded it cannot hold any static charge and this makes grounding crucial for effective control over static electricity. 

 

Summary 

By understanding how ESD garments are tested and what standards they should meet, it becomes possible to guarantee that they will perform their intended functions. With proper testing for resistance and effective grounding of ESD garments, companies can mitigate static discharge risks at workplaces. 

 

Adhering to these guidelines ensures a safe work environment together with the proper functioning of ESD garments and other related appearances as protective wear.