Lead acid motive power batteries produce hydrogen gas and other fumes at 80% recharge point, making proper ventilation in the battery charging area extremely important.

Hydrogen gas is not only colorless and odorless, but is lighter than air, causing the gas to rise to the top of a building. For safety purposes, the concentration of hydrogen in the air should be kept below 1% to reduce risk of explosion.

The calculators provided below are for reference only and BHS takes no responsibility for these guidelines or the results obtained. Applicable statutes and regulations supersede any guidelines provided by BHS. The calculations represent worse case scenario assuming all batteries are producing hydrogen gas at the same time.

If the percentage of hydrogen gas were less than 1%, forced ventilation would not be required. However, the following should be considered before ruling out forced ventilation:

• Is the battery room closed in or open? If the room is enclosed, natural ventilation may not be possible.
• Are there areas in the ceiling where hydrogen gas may rise and collect in greater concentrations? If the percentage of hydrogen gas is greater than 1%, forced ventilation is required.

BHS recommends a Hydrogen Gas Detector (HGD-1) for safety measures. Follow manufacturer’s instructions for proper installation and operation of HGD-1.