Iec 62485-3 Pdf Free Download

[Rhett Espinoza]

Practicallyevery manufacturing plant requires that energy reserves be available in the form of accumulators. Accumulators provide backup power to machines in the event of a mains outage, enable the use of electrically-powered vehicles such as forklifts, trolleys and cleaning machines.

Lead-acid batteries used for industrial applications can be broadly divided into two groups: traction batteries and stationary batteries. The principle of operation for both types is identical. Lead-acid cells contain lead electrodes. The electrolyte is an aqueous solution of sulphuric acid.

Due to the fact that the density of the gas is much lower than that of air (relative density of 0.07), hydrogen will accumulate in the upper parts of the room when released in unventilated or poorly ventilated rooms. Gas may continue to be released from the cells for up to one hour after the end of the charging process.

The first step in determining the risk of formation of an explosive atmosphere in a battery charging room is to identify the type of batteries on hand, as the amounts of hydrogen released into the room will differ depending on the type.

In normal conditions, valve regulated VRLA cells are tightly sealed, but are equipped with valves that allow gas to escape when the pressure inside the cell exceeds a set value. There are also sealed cells available on the market that are guaranteed by the manufacturer not to release gases when operating in specified working conditions. Such cells may be equipped with devices that prevent excessive pressurization.

Due to the inherent nature of the process, hydrogen release during battery charging cannot be completely eliminated. Providing effective ventilation, preferably mechanical, is of paramount importance for ensuring adequate safety in battery charging rooms and locations. A well designed system will reduce the likelihood of formation of an explosive atmosphere inside a room.

Given the above, the ventilation system used in the battery charging rooms must be assessed. Polish standards that define requirements for the safe use and installation of batteries (EN 62485-2:2018 for stationary batteries and EN 62485-3:2014 for traction batteries) suggest a methodology to determine the necessary volume of ventilating air inside a room.

Calculations account for the parameters of charged batteries, but not the internal dimensions of the charging room. Standards allow for the use of mechanical and natural ventilation, provided that an adequate fresh air flow rate is ensured. Both standards suggest the following arrangement of air supply and exhaust vents:

Due to the very low minimum ignition energy of hydrogen, most ignition sources, even those with very low energy, are capable of causing the explosion of a hydrogen-air mixture. Effective ignition sources also include electrostatic discharges, which are often overlooked when adapting a room to serve as a battery room.

The risk of explosion is particularly high when performing maintenance work in battery rooms, for example when topping up electrolyte in the cell. This may require (depending on the type of battery and the refilling system used) the removal of the cell cap, which may cause a sudden release of a significant amount of hydrogen built up inside the cell into the room. When combined with inadequate worker attire (i.e. clothing that does not dissipate static electricity) and failure to use conductive flooring in the area where cells are accessed, this can result in an explosion.

To limit the risk of explosion and reduce battery handling, special recombination plugs are increasingly used in open cells. The plugs bind the hydrogen and oxygen produced during the charging process, creating water that drips back into the cell.

Recombination plugs do not completely eliminate hydrogen emissions, but reduce it to a considerable degree and enable extending the intervals between adding water to the cells, which significantly improves the safety of work in the battery room. Recombination plugs are marketed by multiple companies and can be adapted to the batteries used by the customer.

An Explosion Risk Assessment must also be performed in the room; a careful analysis of its results will indicate whether any explosion hazard zones will be present in the room. The classification will confirm whether additional measures are needed to ensure safety, including but not limited to:

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