Hydrogen is produced during battery charging because of the chemical reaction of liquid inside the battery.If hydrogen gas is allowed to accumulate in an enclosed area, it is readily ignitable and may result in an explosion. During normal operations, hydrogen release from the batteries is relatively small. But during heavy recharge of the batteries, it can increase dramatically depending on the number of batteries, their charge rate, and the size of the room. This danger can be eliminated by monitoring hydrogen build-up and providing adequate ventilation with a hydrogen gas detector.

Explosive gas mixture including hydrogen and oxygen is generated from the battery due to the action of electrolysis of water contained in the electrolyte solution especially the charging operation is close to completion. As a general guide, when the battery is about fully charged, each charging ampere supplied to the cell produces about half a liter of hydrogen per hour from each cell in "normal conditions" at sea level, 25C ambient temperature. Battery manufacturers should be able to provide exact gassing rate, charging voltage, and charging currents for the type of battery installed. These mixture is lighter than the air and would accumulate in the ceiling area of the charging room.

Hydrogen gas when mixed with oxygen or air can be explosive. The lower explosive level (LEL) for Hydrogen is 4% by volume. If sufficient hydrogen collects in a room, it can create an explosive atmosphere. An ignition source such as spark or naked flame may cause a fierce explosion of this explosive mixture. These hazards can destroy equipment or workplace and also cause injury or death to personnel. To prevent this danger it is necessary monitoring hydrogen concetration continously and taking appropriate action if a build up occurs. It is important to consider that smouldering burn may turn into a blaze in the presence of enriched oxygen. Any combustibles in the vicinity, which is not ignited in the air normally, may ignite by itself in the presence of enriched oxygen.

To prevent this hazard it is necessary to monitor Hydrogen level via hydrogen gas detectors and manage the ventilation to prevent the accumulation of an explosive mixture into the charging rooms. Hydrogen gas detector will enable measurement of the gas level and generate alarm indications at defined threshold level. Continuous monitoring in battery rooms is necessary to get early warning and initiate preventative actions before reaching excessive hydrogen gas levels. Prosense Hydrogen detectors and DPX Gas Control Panles have adjustable alarm levels. If these alarm levels are exceeded, the gas control system activates alarms and related switching output relay. Usually low level alarm used to  clear out the hydrogen via turning on ventilation system or increase the fan speed. The high level alarm should never be exceeded if design of the battery charging room ventilation is adequate. In case high level alarm activated more serious actions must be taken, turning off the battery charger or initiating emergency alarm actions.

Prosense Hydrogen gas detectors can monitor gas level in PPM or LEL range that would be suitable depending of the industry and application specifications. Prosense provides concurrent remote monitoring options with DPX panels and detectors integrated to panels. It is important to monitor hydrogen level in battery charging rooms to provide safety and continuity in workplace.

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