Machine safety: The machine safety standards hierarchy

The safety standards hierarchy provides a solid basis for guiding machine designers and preventionists in their risk control efforts, and one or more type-A, type-B or type-C standards will be accessed depending on the situation or the problem encountered.

The identification of applicable standards is part of the documentation step in the assessment and risk reduction process, as described in ISO 12100-2010.

In this blog, the characteristics of each of these three standards types will be discussed.

Type A standards

Basic safety standards which specify the basic concepts, design principles and general aspects that can be applied to all types of machine. These standards are binding for all machines types across the entire life cycle of the machine, from design to disposal. These standards also contain guidelines, methods and tools for determining machine risks and the sequences in which they must be applied.

Examples: ISO 12100, ISO 14121

Type B standards

Standards describing specific aspects of safety or a type of safeguard that can be used across a wide range of machine. Type B standards are divided into two types, B1 and B2.

Type B1 standards deal with particular aspects of safety, usually measurable physical quantities such as safety distances, vibration, noise, temperature, etc.

Type B2 standards deal with protective measures, and describe the requirements they must meet (protective or protective devices) such as locking devices, two-hand control, sensitive devices, etc.

Examples : ISO 13849-1, ISO 13850, ISO13857

Type C standards

Address the detailed safety requirements that apply to a particular machine or a group of machines. These standards describe the hazards and risks with a more detailed way and propose more well adapted protective measures.

Examples: EN692, EN693, EN746-3

When developing a type C standards, committee members are vertically involved across a particular machine or group of machines, which leads to a better approach to specific risks. Thus, when a type-C standard deviates from one or more technical provisions dealt with by this International Standard or by a type-B standard, the type-C standard takes precedence.

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