Workers being caught in running equipment or machinery accounted for 89 workplace fatalities in 2020. This statistic demonstrates the need for employers to install proper machine guarding and for workers to understand the hazards associated with different types of machinery. The ANSI B11 series of standards offers comprehensive guidance to do just that. The B11 standards are divided into three types:

• Type-A: Basic safety standards that provide a foundation for concepts and design that can be applied across different types of machinery.
• Type-B: Generic safety standards concerned with one or more safety aspects or types of risk reduction measures.
• Type-C: Machine safety standards that deal with detailed safety requirements for a particular machine or group of machines. 

Two B11 standards provide a foundation for safety best practices for a broad array of machinery.

ANSI B11.0-2020, Safety of Machinery

ANSI B11.0 is a type-A standard that establishes requirements for the design, construction, operation and maintenance of machinery and machinery systems. It also offers guidance on which risk reduction measures are needed to achieve an acceptable level of risk.

B11.0- 2020 includes:

• Improved guidance on addressing existing (legacy) equipment
• New content on layout analysis for control zones
• New requirements for machinery systems
• New information related to using alternative methods for controlling hazardous energy
• Additional emphasis on the feasibility of risk reduction measures

The standard notes that “the expression ‘acceptable risk’ usually, but not always, refers to the level at which further technologically, functionally and financially feasible risk reduction measures or additional expenditure(s) of resources will not result in significant reduction in risk.”

ANSI B11.19-2019, Performance Requirements for Risk Reduction Measures: Safeguarding and Other Means of Reducing Risk

ANSI B11.19 is a type-B standard that explains employers should implement risk reduction measures. B11.19-2019 uses the hazard control hierarchy as a general structure.  

B11.19-2019 includes:

• Removal of the concept of “complementary equipment and measures”
• A segmentation of perimeter guards (barriers), perimeter risk reduction measures and whole-body access
• Additional guidance in informative annexes, including a significant addition to safety distance and reaching distance for both protective structures and devices
• Clarification of the responsibilities of the supplier, user, integrator/modifier/rebuilder and personnel
• Additional requirements for control functions, including safe conditions, safety-related reset, safety-related sensing field switching, whole body access and span of control

The standard also now uses the term “risk reduction measures” in place of the term “safeguarding,” except in instances where “safeguarding is an integral part of a named risk reduction measure or in cases where replacement may cause additional confusion.”

B11.19-2019 is also being harmonized with several ISO standards:

• ISO 13850, Safety of machinery – Emergency stop function – Principles for design
• ISO 13851, Safety of machinery – Two-hand control devices – Principles for design and selection
• ISO 13855, Safety of machinery – Positioning of safeguards with respect to the approach speeds of parts of the human body
• ISO 13857, Safety of machinery – Safety distances to prevent hazards zones being reached by upper and lower limbs
• ISO 14119, Safety of machinery – Interlocking devices associated with guards – Principles for design and selection

While harmonization does not mean B11.19 is identical to these ISO standards, it makes the standards more closely aligned.

Understanding Machine Guarding

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