Assessing Alternative Measures
Why a machine safety risk assessment process is critical before implementing alternative measures for lockout/tagout.
- By Steve Misuraca
- Jun 01, 2023
Lockout/tagout (LOTO) is a critical safety procedure that is designed to prevent the release of hazardous energy during maintenance, servicing or repair activities. OSHA 1910.147 requires LOTO whenever an employee enters the point of operation of a machine or danger zone to prevent injuries from the accidental release of hazardous energy.
There is an exception to this requirement for minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations. These activities are not covered by the standard if they are routine, repetitive and integral to the use of the equipment for production, provided that the work is performed using alternative measures that provide effective protection.
Electronic Controlled Safe Positioning Devices
Electronic controlled safe positioning devices are often used as alternative measures to provide protection when workers perform these types of activities. These devices are tied into the machine’s electrical circuitry through a PLC or safety relay to stop the machine when the device is initiated. Some commonly used devices include:
- Light curtains. These devices use a series of infrared beams to detect the presence of objects in a specified area. If an object interrupts the beam, the light curtain sends a signal to the machine or equipment to stop moving.
- Laser scanners. Like light curtains, laser scanners use laser beams and are programmed to detect the presence of objects in a specified area. If an object is detected, the scanner sends a signal to the machine or equipment to stop moving.
- Pressure-sensitive mats. These mats are placed on the floor and are designed to detect the presence of a worker by the pressure applied from stepping on the mat. If a worker steps on the mat, the machine or equipment is automatically stopped.
- Interlocks. Interlocks are mechanical devices that prevent a machine or equipment from operating unless certain conditions are met. For example, an interlock may prevent a machine from operating unless a guard is secured in place.
Ensuring the Best Option
However, before implementing these types of measures, an evaluation must be done to ensure the measure is the best option for the hazard and that any residual risks have been accounted for. We are depending on alternative measures to perform as effectively or better than applying LOTO for the same exact task.
This article originally appeared in the June 1, 2023 issue of Occupational Health & Safety.