Derek Box, Marketing Manager for Nightstick, pulls back the curtain on the intricacies of safety-rated lighting

When did you last glance at that right-angle light on your turnout coat and pull out your magnifying glass to read the fine print? Most likely never.

For most, life is too busy for the particular details as long as your certified lighting tools are marked ZONE 0 Certified, and your lights are safety lab certified as Intrinsically Safe.

This is the beauty of safety-rated lighting – it is meant to be simple to understand.

When fully understood, those safety-rated symbols and hieroglyphics reveal secret ways you are protected, give context to your role, and can make you a better consumer with additional confidence in your equipment.

Specialised polymers with static dissipative properties

When a product is used in an ATEX Zone 0 environment, the environment alone poses unique challenges. The use of static dissipative additives in ATEX Zone 0 products has emerged as a crucial measure to mitigate the risks associated with ElectroStatic Discharge (ESD).

These additives play a significant role in preventing potentially catastrophic incidents and ensuring the well-being of all those present in such hazardous environments, but how are additives defined?

Static dissipative additives are specialised substances incorporated into materials, such as polymers, coatings, and composites.

Often found in the housing of a safety-certified torch, lantern, or angle light, these chemical additives help to minimise the buildup and discharge of static electricity, which can ignite flammable substances and trigger explosions.

By facilitating the controlled dissipation of electrostatic charges, these additives significantly reduce the likelihood of ESD-related incidents.

Some dangers are known, while others are unknown, so being prepared for both scenarios with the right certified equipment is a secret worth understanding.

One of the primary functions of static dissipative additives is to increase the electrical conductivity of the materials into which they are incorporated within.

This enhanced conductivity allows any accumulated static charges to flow safely to a grounding point, thus preventing the formation of sparks or arcs that could ignite the surrounding flammable atmosphere.

Moreover, these additives offer long-term effectiveness by maintaining their static dissipative properties throughout the lighting product’s lifespan.

The product makeup is purposely designed to resist leaching, migration, or degradation, ensuring a consistent and reliable level of electrostatic protection over time.

This means that the shelf life of the product is extended for constant use or until it is time to replace it physically.

Furthermore, static dissipative additives are typically formulated to be chemically compatible with the base material, ensuring their optimal dispersion and integration.

This compatibility ensures that the mechanical and physical properties of the materials are not compromised while providing the necessary static dissipation characteristics.

By preventing the accumulation and uncontrolled dissipation of static charges, additives significantly reduce the potential for explosions.

As technology advances, further research and development in this field will continue to improve the safety standards of ATEX Zone 0 products, safeguarding workers and minimising the risks associated with explosive atmospheres.

Overpressure valves and gas venting

One potential danger in a hazardous environment is the release of gas from batteries.

Batteries, especially rechargeable ones, can generate tiny amounts of gas during normal operation and significant amounts during a fault or malfunction.

In an intrinsically safe portable lighting product, this gas must be safely vented to prevent the buildup of flammable concentrations.

Nightstick intrinsically safe lighting products employ various mechanisms depending on the specific design to vent battery gas properly and, most importantly, safely. Here are two common methods:

• Pressure Relief Valve: Some lights have a pressure relief valve built into the battery compartment. This valve allows any excess gas to escape, maintaining a safe pressure level inside the light. The valve typically opens when the pressure reaches four psi and closes once the pressure is normalised.
• Sealed Enclosures: Intrinsically safe lighting may have sealed enclosures that are constructed to be dustproof and waterproof.

It is important to note that intrinsically safety-certified lighting products undergo rigorous testing and certification processes to ensure their compliance with specific safety standards and regulations.

These standards dictate the maximum allowable energy and temperature levels of the lighting tool and the battery to prevent ignition in hazardous environments.

By incorporating mechanisms for venting battery gas, intrinsically safe lights can effectively mitigate the risk of ignition and ensure safe operation in potentially explosive atmospheres.

Electrolyte leakage prevention

Electrolyte leakage can occur in lighting that uses rechargeable batteries, such as lithium-ion batteries, if there is a malfunction or damage to the battery or its casing.

When electrolyte leaks from a battery, it can potentially come into contact with the internal circuitry, causing the light to shut down to prevent a hazardous condition from occurring.

Nightstick’s intrinsically safe portable lighting products employ key design elements to prevent electrolyte leakage.

The torch enclosure, made from impact-resistant polymers, is tough and durable, protecting the battery from damage.

Specialised sealing mechanisms using rubber or epoxy secure housing parts, blocking moisture and contaminants that could corrode the battery.

Safety features like voltage regulators, overcharge protection circuits, and thermal sensors protect the battery further.

Nightstick’s lights also exclude ignition sources, reducing sparking and heat generation.

The lights meet safety standards from organisations such as the IEC and NFPA, ensuring their safe usage in hazardous locations.

Intrinsically safe lighting provides a reliable and secure solution in environments where electrolyte leakage could have severe and, in some cases, fatal consequences.

Encapsulated fuses

Intrinsically safe fuses in portable lighting serve as vital safeguards against electrical faults, helping prevent dangerous conditions such as ignition.

By acting as a check against excessive current, they provide a robust line of defence.

They limit electrical energy by interrupting the circuit if the current goes beyond their specific rating.

These fuses are also instrumental in preventing the formation of sparks and arcs that could ignite flammable substances by promptly interrupting circuits.

Compliant with safety standards set by organisations like the IEC, lights, and their components, including fuses, are suitable for use in hazardous locations.

Redundancy and safety interlocks are another key feature, as lights incorporate additional fuses and resistors to reduce the risk of electrical faults.

Metal content restrictions

Restrictions in IEC 60079 regulations limit the percentage of certain metals allowed in the external housing of Zone 0 rated devices.

Currently, the limit is 10% or less for aluminum, titanium, zirconium, and magnesium. This includes not only the housing, but pocket clips, fasteners, and accessories directly attached to the device.

Metal housings pose practical risks. Conductivity increases chances of circuit completion and sparks from drops.

Chemical reactions with gases in hazardous environments could yield catastrophic results.

Currently, there are no restrictions on engineered polymers in IEC 60079 regulations, making them ideal for Zone 0 rated products.

When combined with static dissipative additives, polymers can now have very low surface resistance that virtually eliminates static charge buildup per standards requirements.

Polymers do not corrode or chemically react with the class IIC gasses found in most hazardous environments. In addition to being lightweight, unlike metal, polymers cannot complete a circuit or create a spark if dropped.

There are many unknown and unseen ways that intrinsically safe lighting protects users from danger.

Another critical factor is the product manufacturers’ experience level with producing intrinsically safe lighting.

A single-source manufacturer ensures consistent quality and safety across an entire product line when purchasing professional lighting products rather than mixing and matching products from several companies.

This is especially important when buying hazardous environment safety lighting.

Nightstick exceeds industry standards in performance, quality, value, and user safety. From penlights to floodlights, above ground or below ground in a confined space, Nightstick has you covered. Find the certification level you need or locate a dealer near you at www.nightstick.com.

This exclusive article was originally published in the June 2023 issue of International Fire & Safety Journal. To read your FREE digital copy, click here.