The importance of safety cannot be overstated when handling large batteries in the industrial and mining environment.
There are numerous safety procedures and guidelines to be followed. It is critical to be prepared for any accident and all employees should be trained to respond properly to all possible circumstances.
Battery racks, chargers, changers, eye wash stations, showers and exhaust systems to vent the gases produced during the charging process are all key components of a safe battery room. In this section we will take a closer look at safety measures to be implemented in our battery charging rooms at the mines.
Dangers and Risks in the Battery Charging Room
What are the hazards of working with batteries?
- Electrolyte (Acid) being splashed/ spilled onto the body (including eyes)
The acid used as an electrolyte is very corrosive and can injure a person if it comes in contact with them.
- An explosion due to ignition of gases both inside and outside the batter
Two gases are released when batteries are charged. Hydrogen is very flammable and easily ignited while oxygen supports combustion.
- Sprains and strains due to incorrect lifting and carrying techniques
The battery is also capable of delivering an electric charge at a very high rate.
- Release and inhalation of hazardous gases
The battery charging process produces gases, including hydrogen that may create adverse exposures for employees. But air quality is commonly overlooked in the distribution environment, especially in older facilities or those whose growth has outpaced their safety function.
During the recharge process hydrogen and oxygen evolve from the lead acid battery when the voltage exceeds 2.35 Volts per cell. If the hydrogen level exceeds 4% of the available volume in the area then the general atmosphere can become explosive – because of this it is recommended that the concentration of hydrogen never exceeds 1% of available volume. Adequate ventilation needs to be provided to keep the hydrogen level below 1%
How to calculate Hydrogen Evolution
Image with recognition to Eternity Technologies
Personal Protective Equipment and Clothing
On the Mining Safety portal we have emphasized the importance of wearing personal protective equipment. This requirement also extends to those working in the battery charging room. The Personal protective equipment (PPE) required when working with batteries includes:
- Approved face shield and goggles
- Approved acid-resistive gloves with gauntlets of at least 6 to 8 inches
- Approved full-length rubber apron
- Slip- and acid-resistive footwear with protected toe
- Nonconductive tools, including scrapers, mops and brushes
- Adequate number of ABC fire extinguishers that are properly inspected/maintained
- Adequate amount of neutralizer
Workers should protect open cuts or lesions with plastic patches. They should also refrain from carrying batteries by their terminal posts and always use an appropriate strap or cradle.
Maintenance and Inspections
We need to emphasize the importance of proper maintenance and inspections of both batteries and facilities:
- Batteries need to be properly maintained - This means they should be clean, properly charged and allowed to cool after charging.
- Batteries must also include cables in good repair and contain the correct fluid levels.
- Remember: Only pour acid into water. NEVER pour water into acid.
- Don’t allow anyone who has not been properly trained to attempt to service a battery.
- Be sure the battery servicing area is clean, uncluttered and free of ignition sources.
- Battery racks should be frequently inspected for damage, corrosion, weld/fastener quality and roller functionality.
- Always consult manufacturer’s operations manuals for details on specifications and care.
- Allow only trained and qualified employees to work on chargers.
Facilities, Eye Wash and Showers
An eye wash/shower system is vital in case any employee comes in contact with battery acid. The system should easily accessible and be as close as possible to the work area without causing any adverse exposure.
A best practice is to have fixed-pipe eye wash/showers system with a drain, as compared to relying on gravity-fed units.
International safety standards include the following as some key items pertaining to eye washes and showers:
- Unobstructed distance: wash stations shall be located in an area that requires no more than 10 seconds to reach—that’s approximately 50 feet. If it is a high hazard, consult a medical professional to determine the appropriate distance for harsh acids and caustics (high hazard=closer distance).
- Eye wash water flow: 3 gallons per minute for at least 15 minutes.
- Water temperature: Tepid, which is defined as 60ºF to 100ºF.
- Plumbed eye wash/shower inspection: The station should be activated weekly to verify proper operation and tested annually. All inspections, activations and testing shall be documented and maintained on file.
- Identification: The location of the eye wash station should be in a well-lit area and identified with a signage.
- Training: All employees who might be exposed to a chemical splash should be trained in the use of the equipment.
At the battery charging room it is also advisable to ensure the implantation of the following measures:
- Permanently store acid neutralizing spill kits, a fire extinguisher, and Personal protective equipment.
- Ensure that the area is adequately ventilated to dissipate harmful gasses.
- The charging room should be maintained between 5°C and 35°C
- Keep all metallic objects away from battery tops.
- Prevent open flames, sparks or electric arcs in the battery charging areas.
- Make sure the battery charging area is adequately light.
- Prominently post precautionary signs, such as No Smoking.
- A spill tray should be installed under the battery to contain any spill.
- If installed batteries are at risk of metal tools or other conductive materials touching terminals, then the terminals should be insulated.
- First Aid Kits should be made available at the site.
Safety Procedures when Charging Batteries
We would also like to share some general safety suggestions when charging batteries:
- Always secure a battery prior to moving or exchanging it. This normally is accomplished using manual stops and/or powered rollers on the battery changer to prevent the battery from falling off the changer.
- Chargers should be robustly mounted to a permanent fixing.
- Chargers should be connected with a suitable lockable isolator/breaker that is compatible with the charger.
- The charger should be installed to the manufacturer’s recommendations.
- Full service access should be allowed for the trucks, batteries and chargers – taking note of all necessary access points.
When working with acid electrolyte:
- Ensure neutralising solutions are available for immediate use
- Add concentrated acid slowly and carefully to the water (adding water to acid causes violent heat generation)
- Stir the mixture with a glass or plastic (teflon) rod
- Ensure stored electrolyte is decanted into an appropriate container (eg glass or polyethylene or polypropylene container or a polylined drum)
- Do not allow metal (except lead) to come in contact with acid or electrolyte
- Allow the electrolyte to cool before checking its specific gravity
- Allow the electrolyte to cool before filling batteries.
Safe Practises and Training
It should be required that all those involved in the process of charging of batteries receive adequate training on safety procedures. The employer is responsible for providing appropriate information and training to employees. Safe work practice requirements should be followed at all times!
Safety training should include:
- Operator and changer responsibilities,
- Required procedures/job tasks,
- Inspection requirements,
- Care and storage of personal protective equipment, and
- Safe work practices.
Remember to review the job task of who is responsible for properly removing and replacing the battery retention plate and when. This activity is critical to preventing battery ejections.
Emergency situations and safety in the Battery Charging Rooms
What do we do in the event of an emergency at the battery charging room?
If electrolyte is spilt:
- Water shower fully clothed if electrolyte comes into contact with any part of the body or such contact with is suspected
- Throw diatomaceous earth or sand (but NOT sawdust) over the contaminated area.
- Remove the earth or sand once it has soaked up the acid/electrolyte.
- Wash down the area with a solution of common washing soda.
- Dispose of any contaminated material safely
The above safety suggestions should reduce the risks of injury and harm at the battery charging rooms in mines. We would like to invite safety experts to share any additional suggestions that they might believe could enhance the safety on mine workers.
[A special word of recognition to advice from materials compiled by James P. Kaletta, CSP, senior vice president of FleetRisk Advisors, a safety consultancy specializing in transportation and logistics.]