Devices
Energy-Isolating Devices
Energy-isolating devices prevent energy from being transmitted from an energy source to equipment.
Energy-isolating devices are the primary means for protecting those who service equipment. Examples of Energy Isolation Devices:
- Disconnect Switches: Used to cut off electrical power to machinery or equipment.
- Circuit Breakers: Interrupts the flow of electrical energy and isolates the electrical system.
- Valves: Used to control the flow of liquids, gases, or steam, such as a shut-off valve for hydraulic systems.
- Blanks and Blinds: Physical devices inserted into pipes to prevent the flow of fluids or gases.
- Bolted Slip Plates: Mechanical barriers that prevent the release of pressure or fluids in piping systems.
Control Circuit Devices
Control circuit devices are devices used to manage and regulate the operation of equipment, typically for controlling, starting, or stopping machinery. Unlike energy-isolating devices, these do not provide physical isolation from hazardous energy. Some common examples of control circuit devices include:
- Push Buttons: Momentary switches that control operations such as starting or stopping a machine.
- Selector Switches: Devices that allow an operator to select from various operating modes (e.g., manual or automatic).
- Relays: Electrically operated switches used to control a circuit by a low-power signal or several circuits by one signal.
- Timers: Devices used to delay or control specific operations in a circuit, often used for sequencing machinery.
- Programmable Logic Controllers (PLCs): Computers used in industrial automation to control processes by receiving input and providing automated output.
These devices do not physically isolate equipment from the equipment's energy source. For this reason, OSHA 1910.147 explicitly rejects control circuitry in the definition of an energy-isolating device.
However, under the "minor servicing" exception provided in 1910.147(a) (2)(ii), circuitry meeting the control reliability requirements of ANSI B11, Machinery Safety Standards, provides the alternative safeguarding measures required under the exception.
Knowledge Check Choose the best answer for the question.
1-5. What category of devices prevent energy from being transmitted from an energy source to equipment?
You forgot to answer the question!