The use of electric forklifts, stackers and pallet carts results in the release of hydrogen gas when charging their batteries. For the safety of nearby people and infrastructure, a charging room must be equipped with a gas detection system for explosive atmospheres. Regularly called upon for this issue in multiple industries, the GazDetect team examines the hydrogen danger in battery rooms and presents dedicated solutions.
Hydrogen in battery rooms
Hydrogen emissions in battery charging rooms
A battery room intended to accommodate the batteries of electric carts and trolleys being charged is a potentially dangerous area. Indeed, charging the battery (particularly those made from lead-acid) releases a dangerous gas: hydrogen.
When recharging an electric cart battery, chemical reactions are taking effect over a period of 6 to 8 hours. It is mainly at the end of this period that hydrogen emissions are released. Depending on the equipment, the power of the batteries and charger, as well as the charging environment, this process can generate particularly dangerous concentrations of hydrogen gas in a charging room.
Today the vast majority of logistics centers, handling centers, as well as many production facilities operate all types of electric carts (forklifts, motorized stackers, pallet trucks, etc). In large fleet configurations, a dedicated battery charging room is essential and risks caused by hydrogen battery release should not be neglected.
Battery hydrogen hazards
Explosive between 4.1 and 74.8% Vol. in the air, in a battery room, hydrogen is likely to explode or cause a fire ignition in reaction with oxygen present in ambient air. When recharging a forklift battery, for example, the risk of explosion is the most important hazard to those present and to the logistics or production infrastructure. Indeed mismanagement of hydrogen concentrations generated by charging batteries has led to fatalities and destruction of production premises in the past.
Hydrogen H2 - CAS 1333-74-0 - also known as dihydrogen, is a very volatile, flammable and explosive gas in reaction with various gases in the air (including oxygen, halogens and oxidants) . Furthermore, the explosive and flammable reactions of this gas are amplified in presence of metal catalysts.
While the main risks in presence of hydrogen are explosion and fire, this gas is also dangerous when inhaled. Personnel subject to hydrogen inhalation in a battery room may experience various health effects (headache, dizziness, asphyxiation).
Explosion and fire hazards due to hydrogen therefore require the implementation of safety measures in a battery charging room.
How to secure a battery room
Regulation : battery room safety requirements
In order to secure a battery charging room regulations impose numerous measures. The May 29, 2000 order and the May 31, 2006 Decree No. 2006-646 govern the use of lead-acid batteries. A dedicated battery room is mandatory from 50 kW of direct current power for recharging electric trolleys and carts lead-acid batteries. This regulatory obligation is the first safety requirement against hydrogen emissions, fire and explosion hazards.
For a charging room, regulations also impose safety design and equipment such as the presence of an eye wash, an acid retention tank, a hazardous area display, fire extinguishers, a fireproof floor, waterproof coating for polluted water, fire doors and IP55l lighting.
Safety regulations also require the presence of mechanical ventilation to limit the presence of hydrogen to 1% of the battery room’s volume. In addition to this requirement, it is mandatory to automatically shut down the chargers in case of a ventilation fault. Finally, the presence of a hydrogen measurement unit is required in order to activate the ventilation and emergency stop the battery charge.
In addition, to ensure everyone's safety, staff working in or near a battery room must be authorized to intervene and must be educated to the potential dangers.
In compliance with ATEX standards and regulations, a charging room for electric carts must be ATEX classified (zone 1 or 2). ATEX zoning implies the presence of an explosive atmosphere requiring maximum precaution. In logistics, handling or production environments, the case of a battery room with hydrogen concentrations in the air constitutes an ATEX zone.
All equipment operated and brought into an ATEX classified area must be approved in order to minimize explosion risks. Thus, a battery charging room must, for example, be equipped with ATEX-certified mechanical ventilation and gas detection system.
The ATEX battery room
The hydrogen detection system for battery rooms
In a battery room, the installation of a hydrogen detection system is essential to ensure personnel and infrastructure safety. The presence of hydrogen detectors and a gas controller unit is also required by the regulations governing the use of batteries.
The battery room hydrogen detector
Measurement of gas concentrations in a battery room can be carried out by an ATEX fixed hydrogen detector. These devices, like the OLC and OLCT 100 detectors are ATEX approved and fit perfectly into a battery charging room. This Oldham Simtronics Teledyne gas detection equipment constantly monitors the hydrogen concentration’s level. The measurement will be carried out in % LEL (explosivity) using a gas detection catalytic sensor. The battery room fixed gas detector can be connected to a controller unit via a 4-20 mA linear output or via a Wheatstone bridge output. The number of detectors to be installed depends on the size of the area to be covered. This equipment must be installed at a height in accordance with the H2 gas volatility.
Among the fixed gas detectors, the Spyglass SG50 optical flame detector can visualize hydrogen fires with its near-infrared video option, and the Spyglass IR3-H2 flame detector locates hydrogen up to 30 meters away.
The gas detection controller acts as the main supervision for the battery room safety. The Oldham MX32 controller is an ATEX equipment perfectly suited to hydrogen monitoring in battery charging rooms.
A fixed gas detection system is based on simple operations. The concentration of hydrogen generated by charging the batteries of forklifts and electric stackers is transmitted by the detectors to the controller unit. Measurement centralization in the device then makes it possible to exercise constant monitoring. The gas controller connected to various servo controls automatically actuates those based on the gas concentration level.
The gas detection controller
In case of an electric forklift battery room, the gas detection controller can be installed outside the room. In compliance with regulations in force, it will monitor the gas level and immediately stop charging the batteries in case of a dangerous hydrogen concentration. Likewise, the charge will be interrupted in the event of a ventilation fault. At the same time, alarms and light signals can be connected to the gas controller in order to reach an optimal safety level.
A portable hydrogen gas detector in addition
In addition to the fixed hydrogen monitoring installation, the maintenance or fire safety departments can use a portable gas detector (such as portable 4-gas detector). When dealing with battery rooms, portable gas monitors constitute a very valuable addition in case of an alarm to lift any doubts. Very affordable devices are available as explosive combustible gas monitors (0-100% LEL H2) such as the Xam2500-EXPLO combustible gas detector from Dräger.
Our GazDetect experts are at your disposal to help you choose your hydrogen detection equipment for your battery charging room. Our teams support you in the choice of equipment and install your equipment anywhere in France.