Type of Energy Source

Electrical energy:
Electricity is the most common type of hazardous energy. For most equipment, the electrical energy flows through a circuit breaker that can be isolated and locked out. In some cases, the equipment may simply have a cord that can be unplugged and locked out.
‍Examples: Table saw; Electric arc furnace; Light bulb; Computer; Air conditioning.

Hydraulic energy:
In a hydraulic system, power is transmitted by the circulation of pressurized fluid to a motor that converts it into mechanical energy. Putting equipment into its de-pressurized, natural state should be one of the first steps in the lockout/tagout program.
‍Examples: Equipment such as cranes, forklifts, jacks, pumps and fall arrest safety harnesses use hydraulics to lift and lower objects.

Pneumatic energy:
Pneumatic energy is similar to hydraulic energy, except it utilizes pressurized air instead of fluid. Some machines use pressure tanks to build up energy in the machine before it is needed. Always release pneumatic energy before beginning a job.
‍Examples: Rock drill; Jackhammer; Riveter; Forging press; Paint sprayer; Blast cleaner.

Gas energy:
Gas energy refers to pressurized gases that are not pneumatic. The pressure can be relatively static (such as surge pumps/ tanks or pressure tanks) or in motion though tubing or hoses. Gases may be needed for the equipment to perform a given function, for example, natural gas in heaters or nitrogen gas in an intensifier. In some cases the gases present are part of the process or final product.
‍Examples: Propane gas tanks and lines; Boilers; Compressed gas cylinder and valves.

Water energy:
Water energy refers to the power created by the flow of water. The pressure can be relatively low (e.g. typical city or process water circuits). Higher pressure circuits may be found in systems where pumps are used. Some applications may have heated water, typically due to the water being used for cooling or other temperature control purposes. Water energy must be controlled via a mechanical energy isolating device that physically prevents the release of the water.
Examples: Water pipes, pumps, turbines; Water processing equipment; Sewage systems.

Steam energy:
Boilers or gasifiers often use steam to move energy through the mechanical system. Steam powers engines, turns turbines, carries heat energy, sterilizes, and moisturizes.  The presence of steam typically includes the need to dissipate the thermal heat before work begins. Steam energy must be controlled via a mechanical energy isolating device that physically prevents the transmission or release of the steam. Plant-specific handling instructions are often in place. Be aware of any special handling procedures or PPE that may be required.
‍Examples: Process fluid heat exchanger; Reboiler; Reactor; Combustion air preheater; Heat transfer equipment; Vacuum pump, Steam turbine; Cooling pump; Distillation tower; Soot blower; Pellet mill.

Chemical energy:
For lockout/ tagout purposes, chemical energy is usually the power related to pressurized liquids that are not water. But is can also refer to the energy stored and released through chemical reactions. The pressure can be relatively static (such as holding tanks) or in motion though tubing or hoses. Chemicals may be needed for the equipment to perform a given function, for example, cutting fluid or cooling fluids. In other cases the chemicals are part of the process or final product (e.g. paint, adhesives, etc.). Chemical energy must be controlled via a mechanical energy isolating device that physically prevents the transmission or release of the chemical. Specific handling instructions may be required for some chemical. Be aware of any special handling procedures or PPE that specific chemicals may require.
‍Examples: Chemical supply lines; Metalworking equipment; Printing jets; Paint sprayer; Batteries.

Mechanical energy:
Moving objects (e.g. robot arms, movable saw blades, springs, crushing parts, etc.) have mechanical energy. These objects should be secured before work begins. This is an often-overlooked form of energy and it should not be ignored.
‍Examples: A mechanical arm that is positioned up in the air during normal machine operations. It may begin to move when the electricity is cut that was holding it up; Farm equipment.

Other energies:
Certain equipment and/or processes may have an energy source that is not addressed by the typical energy source definitions. These unique energy sources may present specific dangers that need to be identified and properly controlled. For these conditions, unique lockout/tagout procedures and energy control tags are developed as needed. Controls for unique hazardous energy sources may be specific for each application, but in many cases the control devices will be similar to those used for other, traditional energy sources.
Examples include:‍

• Vacuum-- A deep or large volume vacuum draw may require a controlled return to atmosphere;
  
• Grain-- The flow, or potential flow, of grain in large volume breweries or food-processing plants may require specific controls to prevent danger to personnel due to unrestricted movement of material;
  
• Powder-- Lightweight particulates, either a material used in the process or a byproduct of the process, may result in airborne contaminants that present inhalation or combustion hazard.