A glass tube (often called a glass cover or lens) in an explosion-proof light fixture serves several crucial purposes:

Isolating the External Explosive Environment

This is its primary and most vital function. In hazardous locations where flammable gases, vapors, dusts, or fibers are present (like chemical plants, oil depots, or coal mines), ordinary lighting fixtures can pose a serious risk. Electrical sparks, high temperatures, or malfunctions from a standard light could easily ignite the surrounding explosive mixture. The explosion-proof glass tube, working seamlessly with the lamp body, forms a sealed enclosure designed to withstand internal explosion pressures. This setup effectively prevents external explosive substances from entering the light fixture, thereby eliminating the risk of an external explosion.

Containing Internal Explosion Pressure

Should an electrical fault occur inside the fixture (e.g., a short circuit or an arc), leading to a minor internal explosion, the explosion-proof glass tube must be robust enough to withstand the resulting pressure. This ensures that the explosion doesn't breach the enclosure and ignite the hazardous atmosphere outside. It's built to remain intact, confining the energy and flames of any internal blast within the light fixture.

Preventing Fragment Dispersion

Explosion-proof lights typically use tempered glass or specially manufactured glass tubes. Tempered glass is specially treated for increased strength and impact resistance. Even in extreme cases where the glass might break, it's designed to shatter into small, blunt pieces rather than sharp fragments. This significantly reduces the risk of injury to personnel and prevents secondary accidents (like glass shards igniting combustible materials).

Maintaining Light Transmission

As a lighting component, the glass tube must allow light to pass through efficiently, ensuring the light source provides sufficient illumination. Some explosion-proof glass tubes are also specially treated to optimize light distribution and reduce glare.

High Temperature and Corrosion Resistance

Hazardous locations often involve high temperatures or corrosive substances. The explosion-proof glass tube needs to be highly resistant to heat generated by the light fixture during operation. Additionally, its material must withstand chemical corrosion in specific environments to ensure long-term stability and safety.

Protecting Internal Components

Beyond its explosive-proof functions, the glass tube also physically protects the light fixture's internal components (like LED chips or bulbs) and other electrical parts from external dust, moisture, liquids, and physical impact.

In essence, the glass tube of an explosion-proof light fixture is a critical part of its overall safety design. Through its robust structure, sealing capabilities, pressure resistance, and shatter-proof properties, it ensures the light operates safely and reliably in hazardous environments, preventing fires and explosions.