A warning device can provide a visual alarm such as a flashing light or an audible alarm such as a horn or siren.
- These devices signal that a problem is either about to occur or has just happened.
- With a warning effect, the response is not automatic; someone has to take action.
A warning signal must be triggered by something in the process, usually a sensor similar to the ones shown in the lesson on shutdown effects.
- The alarm can be visual, audible, or both.
A variety of warning devices are available.
- For audible warnings, there are sirens, horns, bells, and even voice synthesizers.
- For visual alarms, there are lights that flash, rotate, strobe, or just light up.
- Even process control panels can be programmed to flash when there are process problems.
Words of Caution about Warning Mistake-Proofing Solutions
- If you do use warnings, the audible or visual signal must stand out from background noise and lights.
- If audible alarms are used, be careful not to exceed noise standards.
- Be careful of “alarm silence buttons.” It is easy to silence the alarm and then forget to take action.
- Operators need thorough training on how to react to warnings.