Glossary · Safe work, maintenance and competence
Energy isolation
Also known as: isolation of energy sources
In machine safety, energy isolation is the physical prevention of energy transmission or release to equipment, using an energy-isolating device such as a disconnect switch, a line valve or a blank. Control circuit devices such as push buttons or selector switches are not energy-isolating devices.
- Machine safety
- Maintenance
- USA
In one sentence
Energy isolation physically cuts equipment off from its energy sources. A stop button or safety function does not isolate.
Example
Before cleaning a mixer, the operator opens and locks the main disconnect, closes and locks the pneumatic supply valve and vents the line, isolating both the electrical and the pneumatic energy.
How it applies
- Machine safety: Isolation must cover every energy source: electrical, pneumatic, hydraulic, mechanical, thermal and chemical. Stored energy left after isolation must then be dissipated or restrained.
- Design: ISO 14118 on the prevention of unexpected startup expects machines to have lockable isolation devices. Designers who place them accessibly make correct procedures easier to follow.
- Technical documentation: List each isolation point with its location, energy type and how to verify isolation. Photos or labels at the point help more than text alone.
- Evidence: Isolation followed by securing and verification is the basis of lockout/tagout; the records show each step was done.
Energy isolation vs. safe torque off
Safe Torque Off and other safety functions stop motion through the control system. Energy isolation physically separates the source. Only isolation is suitable for protecting people during servicing covered by lockout/tagout.