Don't Underestimate It! Static Electricity Can Be a Fatal Threat in Risky Work Environments

Hey APT friends, did you know? Static electricity can pose a serious threat in explosion-prone industries. Static charges accumulating on low-conductivity materials can trigger fires or explosions. In risky areas, PPE such as helmets and eye protection made of plastic can store electric charge and create dangerous sparks. 
PPE must meet electrostatic standards, such as:

• PN-EN 1149-1 (surface resistivity)
• PN-EN 1149-3 (charge decay)

Although there are no specific standards for helmets and eye protection, researchers from CIOP-PIB have developed new testing methods to ensure PPE is safe to use in hazardous areas. Stay safe, avoid static electricity!

1. FElectrostatic Phenomenon: Causes, Parameters, and Hazards

Hey APT friends, did you know? Static electricity occurs when electrostatic charges accumulate on non-conductive or isolated materials. The amount of charge is influenced by the composition, structure, and conductivity of the material. High-resistance materials are more easily electrified, while conductive materials quickly discharge charge if not insulated. If charge exceeds limits, electrostatic discharge can trigger fires or explosions, especially in areas with flammable materials. 
That’s why it's essential to ensure materials and PPE meet safety standards, including resistance tests and the ability to withstand electrostatic charge.

2. Protective Helmets: Functions and Key Elements

A protective helmet consists of three main elements:

• Shell: Absorbs and dissipates impact energy and reduces the risk of static electricity. Common materials: polyethylene, ABS, or fiberglass composites.
• Harness: Distributes impact force evenly, absorbs energy, and provides comfort.
• Main strap: Keeps the helmet stable and securely positioned on the head, even with movement or shock. 

The combination of these three elements ensures the helmet is effective in providing protection and comfort in high-risk environments.

3. Interior of the Protective Helmet: Harness and Main Strap

The interior of the helmet consists of the harness and main strap, which complement each other.

• The harness (made of textile materials like polyamide/polyethylene) maintains the stability of the helmet, absorbs energy, and distributes impact to reduce injury. However, friction with hair can generate static electricity, especially in electrically hazardous areas.
• The main strap ensures the helmet stays stable and in the correct position, providing maximum protection. 
  Research by CIOP-PIB evaluates the electrostatic properties of protective helmets, with analysis results listed in the following table.

4. Eye and Face Protection in the Workplace

Eye and face protection is crucial in high-risk workplaces. There are four main categories of eye protection: safety glasses, protective goggles, face shields, and welding shields. Face shields, made from materials such as polymethyl methacrylate, cellulose acetate, or polycarbonate, protect the face from unexpected impacts.

5. Material and Advantages of Polycarbonate

Polycarbonate is often used because it is strong, UV-absorbing, and can be tinted. However, it has drawbacks, such as high resistance and low scratch resistance. To address this, face shields are often coated with a hardening layer.

6. Anti-Fog Features

Many face shields come with an anti-fog coating to maintain visibility, although this coating can affect their electrostatic properties, depending on the material and coating used. Choose appropriate protection to ensure safety and comfort.

7. Research Methodology: Evaluating Product Feasibility in Hazardous Areas

This research evaluates the feasibility of products in explosive-risk areas using several methods, such as measuring the product's ability to create explosive mixtures through material electrification and charge transfer during electrical discharge. The study also tests the electrostatic properties of the product materials to ensure their safety. According to PN-EN-05200:1992, products are considered anti-electrostatic if they do not experience harmful electrification. The methods used include measuring surface resistance and charge voltage after conditioning the products for 24 hours.

8. Helmet Surface Resistance

Surface resistance measurements for helmets follow the EN1149-1:2006 standard using conductive silver electrodes (ELECTRONE 40AC), adjusted to the helmet shape. The length and distance of the electrodes follow a geometric ratio of 10.

The formula for surface resistance and resistivity relationship is: 
ςs = k * Rs (k = geometric ratio, Rs = surface resistance). 
The measurements were conducted using the TO-3 instrument (Germany), with a range of 10 TΩ – 160 TΩ, voltage of 100–500 V, and inside a Faraday cage after conditioning.

9. Electrostatic Voltage

To measure the electrostatic voltage on helmets and face shields, we rubbed the samples with three materials (bristle brush, fleece plastic, human hair) for 30 seconds. The measurements were taken using the JCI 140 meter (USA), with the meter positioned 100 mm from the product. The results confirm that the products are safe to use in electrostatic-risk environments.

10. Study Results and Discussion

In this section, we present the analysis results without considering the measurement uncertainty, which is very small compared to the obtained standard deviations.

10.1. Surface Resistance

The test results showed a standard deviation of 0.3–16%. The ABS helmet exhibited the highest resistance (1.95E14 Ω), while the heterogeneous helmet (fiberglass and polyester resin) exhibited the lowest resistance (3.51E7 Ω). High humidity reduced surface resistance, especially on helmets B and C.

• Face and Eye Protection Resistance Testing 
  The resistance of eye and face protection was consistent with the theoretical values of the materials, although there were slight differences due to composition and additional coatings. Resistance slightly decreased with increasing humidity, and some samples showed deviations of more than 20% due to testing voltage. 
  Overall, the results show the influence of air humidity and voltage on the surface resistance of helmets, as well as eye and face protection. 
  The results of the eye protection tests are presented in Table 6.

10.2. Electrostatic Voltage

The electrostatic voltage testing was conducted according to the conditions in Table 3 after the samples were conditioned for 24 hours. The results are presented in Tables 7 and 8. 
This study evaluated materials in explosive atmospheres based on Directive 1999 and PN-E-05201:1992. The results show:

• Materials must have surface resistance ≤ 10⁷ Ω.
• Materials with resistance 10⁷ Ω < ςs ≤ 10¹⁰ Ω are allowed for ignition energy ranging from 10⁻⁴ J to 0.1 J.

Helmet E meets these criteria at humidity > 65%. Voltage was also tested, and the helmet and protective glasses meet the established ignition energy threshold.

CONCLUSION

In conclusion, the tested products have the potential to accumulate electrical charge in explosive atmospheres, highlighting the importance of using confirmed anti-static PPE. This research method has proven effective in evaluating surface resistance and electrostatic voltage on materials with irregular shapes, such as helmets and face shields. Further research is needed to improve the evaluation methods and selection of PPE in explosion-prone zones.

Source: Jachowicz M. 2013. Electrostatic properties of selected personal protective equipment regarding explosion hazard. Journal of Sustainable Mining. 12(1):27-33.  https://doi.org/10.7424/jsm130106

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Hello APT Friends 👋👷‍♀️👷‍♂️

Did you know that static electricity accumulating on low-conductivity materials can pose a serious safety hazard in the workplace? For example, Personal Protective Equipment (PPE) made of plastic materials, which, instead of providing protection, ends up storing electrical charges that can trigger dangerous sparks.

This highlights the critical importance of ensuring that materials and PPE meet safety standards. Researchers from CIOP-PIB have developed an innovative testing method to guarantee that PPE is safe to use, particularly in hazardous environments.

Curious to learn more about their findings? Let’s dive in!

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