13.5 REQUIREMENTS FOR SPECIFIC R&D EQUIPMENT
13.5.5 Batteries
Batteries are used in multiple applications. Specialized types exist that are suitable for different applications.
Lead-acid storage battery types are the lead-antimony and the lead-calcium. The lead- antimony battery is low cost, high efficiency, small size and long life. Typically, the lead-calcium is chosen for use in UPS systems due to the similar characteristics of lead-antimony coupled with lower maintenance requirements. Both types use dilute sulfuric acid as the electrolyte.
Alkali storage battery types are the nickel cadmium and the nickel metal hydride. These batteries use compounds of nickel peroxide and iron oxide for the plate materials, and potassium hydroxide as the electrolyte. Storage batteries of this type perform well in extremes of temperature.
13.5.5.1 Other Batteries
Specialized batteries for applications include silver zinc, silver cadmium and mercury.
Manufacturers’ data sheets provide guidelines for safety for these and other battery types.
13.5.5.2 Hazards 13.5.5.2.1 Chemical Hazards
For each battery type considered for use, obtain Material Safety Data Sheet (MSDS) information and understand the specific hazards involved before use.
Chemicals associated with battery systems may include:
1. Cadmium (Cd);
2. Lead (Pb);
3. Lead peroxide (PbO2);
4. Lithium hydroxide (LiOH);
5. Potassium hydroxide (KOH);
6. Sodium bicarbonate (NaHCO3);
7. Sodium hydroxide (NaOH); and 8. Sulfuric acid (H2SO4).
Many of these chemicals (and other battery components not listed here) are corrosive, poisonous and/or flammable. Possible consequences of a ruptured container or spilled electrolyte include:
1. Fire;
2. Explosion;
3. Chemical burns; and
4. Reactions to toxic fumes, solids or liquids.
13.5.5.2.2 Electrical Hazards
Electrical safety during battery operations is primarily concerned with prevention of a direct short circuit across one or more cells. Due to the large amount of stored energy in the battery cells, along with the low internal resistance of the cells, a short circuit could have catastrophic results including an explosion of the cells involved. Suitable clothing has been discussed above.
Personnel conducting electrical work on battery systems are to follow the following guidelines:
1. Tools shall13.36 be insulated. Vinyl electrical tape may not be used as an insulator because the tool does not meet the design and construction requirements.
2. Only instruments having a non-conductive case (e.g., the yellow rubber holster provided with some multimeters) are permitted in the vicinity of battery systems.
3. Storage battery systems may present terminal voltages of 48, 125 or 250 V DC. If the physical construction of the battery system permits, inter-cell or inter-tier cables should be disconnected when performing work on the battery system.
4. If one terminal of the battery system is bonded to ground, an additional hazard exists.
Single-point contact between an exposed battery terminal and surrounding structures could result in very large short-circuit currents and possibly lead to fires or personal injury.
13.5.5.2.3 Physical / Mechanical Hazards Individual cell containers:
1. May weigh in excess of 70 lbs;
2. Are not typically provided with handles; and
3. May be slippery and difficult to hold, especially when wearing gloves.
Removal and replacement of these containers necessitates work in positions which are:
1. Awkward;
2. Uncomfortable; and
3. Possibly unstable
Possible consequences include:
1. Muscle strains, falls, or dropped containers; and 2. Dropped containers which rupture and spill electrolyte.
13.5.5.3 Design and Construction The following need to be considered:
1. Battery systems should be isolated by elevation, barriers, or enclosures to preclude accidental contact with energized terminals, conductors, cases, or support structures.
2. Battery systems should be provided with overcurrent protection devices.
3. A means of partitioning or ‘sectionalizing’ battery systems should be provided to allow multiple or single batteries to be disconnected (see to Figure 13-7).
4. Safety devices should be designed to withstand the mechanical forces caused by the large currents.
5. Suitable grounding should be provided.
6. Provisions should be made to contain possible spills of electrolyte.
Figure 13-7. Example of sectionalizing a large, multi-tier battery system.
13.5.5.4 Operation and Maintenance
Workers should handle the equipment carefully. The battery manufacturer’s installation, operating and maintenance instructions give guidance about appropriate handling. Personnel attempting physical movement of battery containers should plan their work accordingly.
Safety during electrolyte-handling operations (measurement of cell specific gravities, addition of distilled water, addition or removal of electrolyte) requires the use of certain PPE and other materials. The following protective equipment shall13.37 be available to personnel performing battery maintenance tasks:
1. Face shield and chemical splash goggles;
2. Acid-tolerant gloves and apron, and shoe covers if the work warrants;
3. Emergency shower/eye wash equipment capable of delivering 450 gallons of water within a 15-minute interval;
4. Sodium bicarbonate solution (neutralizing agent for cleaning cell containers and neutralizing acid spills);
5. Class C fire extinguisher; and
6. Adequately insulated tools of appropriate-length.
If the cell container is tipped over, electrolyte may spill from the flash arrestor assembly. The flow of electrolyte may not be rapid, but is still a safety hazard. When lifting or moving electrolyte-filled containers, ensure they always remain in an upright position.
In the event of an electrolyte spill:
1. Minimize contact with the electrolyte by leaving the spill area.
2. Rinse contaminated protective equipment with water and sodium bicarbonate.
3. Remove contaminated clothing.
4. In case of skin contact, immediately flush with water followed by washing with soap and water.
5. Do not attempt to neutralize with sodium bicarbonate any acid spilled on the skin.
6. In case of eye contact, flush eyes for a minimum of 15 minutes, then provide transport for the individual to medical facilities. This is to be done regardless of the apparent severity of the injury.
7. Electrolyte-contaminated material or equipment is considered hazardous material and is to be treated and disposed of as such in accordance with current guidance.
Appropriate gloves and other PPE shall13.38 be worn to minimize the hazard due to toxic material exposure. Workers should wash their hands with soap and water after completion of the work.
Eating or drinking in the vicinity of the battery system should not be permitted.