Facilities that use forklifts for moving and lifting heavy goods require charging stations for forklifts. When forklifts use lead-acid batteries, the charging stations pose an explosion risk. During the charging process of lead-acid batteries, ionization occurs at the positive pole, causing H2O molecules to ionize into H+ and O2-,2 H+ ions combine to form H2, a flammable gas. H2 tends to accumulate at the corners of building roof, creating an explosion risk.
Forklift battery charging station is one of the high risk area in a facility, so an Explosion Protection Document (EPD) is required.
Hazardous Area Classification (HAC) is one of the important parts of an Explosion Protection Document (EPD).
When conducting a HAC, the first step is to determine the grade of release of H2. During the battery charging, the release of H2 is occasionally, so secondary is the grade of release of H2 in this case.
Regarding ventilation, when a battery charging station is located in an open area, the type of ventilation is ‘Natural’, with a ‘High’ degree of ventilation and ‘Good’ availability. In this scenario, a ‘Zone 2’ classification without extension can be applied. If the battery charging station is inside a building without forced ventilation, the ventilation type is still ‘Natural’, but the degree is ‘Medium’, and the availability remains ‘Good’. Thus, a ‘Zone 2’ classification within the battery compartment is applied, about 0.75m extend from the battery. Some facilities install mechanical ventilation above the battery charging station, in this case, the ventilation type is ‘Mechanical’, the degree is ‘High’, and ‘Good’ for the availability. Therefore, a ‘Zone 2’ can be applied, with a 0.75m extends from the battery in case of the failure of the mechanical ventilation.
These classifications depend on the situation that the roof of the battery compartment is opened during charging. If the roof is closed, the degree of ventilation would be low, and the availability would be ‘poor’, leading to a ‘Zone 1’ classification within the battery compartment.
For a zoning area: safety signage, avoiding source of ignition, training, and other control measures can be implemented to reduce the risk of explosion.
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