Where is Explosion Proof Class I, Division 1 Group B (Hydrogen) Equipment Used? (8/17/2026)

This classification is for flammable gases, liquids and vapors with a MESG less than 0.45 mm and a MIC ratio of 0.40 or less. Hydrogen is the most common combustible substance in this group and features low ignition energy.

Article - August 17, 2026 By LarsonElectronics.com

Explosion Proof 150 Watt High Bay LED Light Fixture - 10,000 Lumens - Group B - Hydrogen Approved

Where is Explosion Proof Class I, Division 1 Group B (Hydrogen) Equipment Used?

The Class I, Division 1 Group B explosion proof rating covers atmospheres containing hydrogen or gases and vapors with comparable hazardous characteristics. Hydrogen is the most common combustible substance in this group and features low ignition energy. This classification is for flammable gases, liquids and vapors with a MESG less than 0.45 mm and a MIC ratio of 0.40 or less.

Petroleum Refineries and Battery Storage

Petroleum refineries and petrochemical facilities can contain Group B locations when hydrogen is present as part of the refining process. Hydrogen is widely used in processes such as hydrotreating. Areas surrounding hydrogen-containing process equipment may require specially rated electrical equipment depending on the facility's hazardous-area classification.

Class I, Division 1, Group B equipment may also be found in battery charging and energy-storage facilities where hydrogen can be generated. Lead-acid and VRLA batteries release hydrogen gas during normal charging. Under abnormal conditions, such as overcharging, hydrogen generation can increase by as much as 50 times. Without adequate ventilation and continuous monitoring, this colorless and odorless gas can accumulate within an enclosed space and reach hazardous concentrations. At a concentration of approximately 4% by volume in air, hydrogen reaches its lower explosive limit (LEL), creating a significant risk of fire or explosion.

Hydrogen Processing and Fueling

One major application for Class I, Division 1, Group B equipment is hydrogen processing and storage facilities. Hydrogen can be present around hydrogen compression equipment, storage vessels, filling stations, piping connections and process equipment. Hydrogen fuel cell facilities and hydrogen fueling infrastructure are also applications that utilize Class I, Division 1 Group B equipment. A hydrogen fuel cell facility is an industrial or commercial installation where hydrogen is supplied to fuel cell systems that convert hydrogen directly into electrical energy through an electrochemical reaction.