Battery banks are used to store energy generated by renewables, emergency power in data centres and motive power for electric forklifts and carts etc . The need for gas monitoring occurs while these batteries are being charged. Typically, batteries are continuously trickle charged. After heavy battery use or discharge, a higher charge voltage is used to quickly restore the batteries to full capacity. This charging process generates hydrogen gas which is emitted into the battery storage / recharge room. The faster the charge rate is, the higher the hydrogen generation rate.
In addition to battery back up rooms and Data centres. Battery rooms that accommodate forklift truck batteries whilst being charged are a potentially dangerous area. Indeed, depending on the battery chemistry used , charging these batteries espcially when from low state of charge can result in the generation of Hydrogen Gas .
When recharging an electric cart battery, The Absorption Cycle where the battery charge voltage is held high and the current gradually reduced can last up to 8 hours. It is mainly at the end of this Absorption Cycle 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.
Warehouses , Logistics centres, as well as many production facilities operate all types of electric vehicles such as forklifts, motorized stackers and pallet trucks. Companies with large fleets of these electric vehicles, often have a dedicated battery charging room therefore the risks caused by hydrogen battery release should not be overlooked.
Hydrogen is a highly flammable gas. The lower explosive level (LEL) for Hydrogen as 4% by volume. If sufficient hydrogen collects in a room, it can potentially explode if ignited. The likelihood of this happening depends on the number of batteries, their charge rate, the size of the room, and the ventilation available for the room. Although this may not be a common occurrence, the potential hazard exists with any type of enclosed battery room. This danger can be eliminated by monitoring for a hydrogen build-up, and taking appropriate action if a build up occurs.
Hydrogen is the lighest gas so any leaking Hydrogen will collect in the roof spaces above the batteries / Charging area. Therefore any Gas monitoring sensors should be positioned in these areas to allow the earliest detection of potentially dangerous levels of Hydrogen .
In compliance with ATEX Regulations a large battery backup roon or charging room 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, A Large battery room where hydrogen concentrations could reach Combustible levels ( 4% vol for Hydrogen ) would constitute an ATEX zone.
In a battery room, the installation of a hydrogen detection system is essential to ensure personnel and infrastructure safety. One or more ATEX compliant Detector head should be installed in the area where the Hydrogen is most likely to gather .
These devices, like the Riken Keiki GD-A80 are ATEX approved and perfectly suited to battery room monitoring appilcations. The GD-A80 uses a Catalytic ccombustion or New Ceramic sensor to constantly monitor the level if Hydrogen in the Detection ( ATEX ) Zone . The measurement range would normally be 0-100% LEL with alarm levels typcailly set at 10% and 20% LEL to give ample warning of a build up of Hydrogen towards the LEL . The battery room Fixed Gas Detector Head(s) would then be connected to a RM-6000 single channel or RM-5000 Multi channel Gas monitor panel . The number of detectors to be installed depends on the size of the area to be covered. The Monitor panel would be installed at ground level outside the ATEX Zone.
Plant rooms are often situated underground. This is by design to save space or by virtue of being built into existing basements or chambers. Underground Plant Rooms often contain an array of machinery such as Pumps, Boilers, Sprinkler Systems or Generators.View Story
Disclaimer : Information given in this article is for general guidance only, and is based on experience and is not intended to replace advise from professional gas sensor location experts and/or gas mapping services, that can provide accurate bespoke design.
For more information about positioning fixed gas detectors, further guidance can be found in the new Gas Mapping Standard BS 60080 (Fire and Gas Mapping ), IEC 60079-29-2 (Explosive atmospheres – Part 29-2: Gas detectors – Selection, installation, use and maintenance of detectors for flammable gases and oxygen), and also EN 45544-4 (Workplace atmospheres – Electrical apparatus used for the direct detection and direct concentration measurement of toxic gases and vapours. Guide for selection, installation, use and maintenance.). Additionally, The CoGDEM ( Council of Gas Detection and Enviromental Monitoring ) Guide to Gas Detection is an excellent general user guide for Gas Detection, written by those in the industry.View Story
Catalytic combustion sensors are the standard method for detecting combustible gases including Hydrogen, however in order to operate a minimum of about 10% Oxygen needs to be present. IR sensors are a good solution to this problem for measuring most combustible gases in an inert environment where O2 levels are below 10% volume but IR sensors cannot detect Hydrogen.
Riken Keiki offers several solutions around this problem.View Story