ASTM F2491-20

• Abstract:

  SIGNIFICANCE AND USE; 3.1 This guide may be used to provide a consistent method for determining load ratios for technical rescue equipment and systems. ; 3.2 Use of this guide will help to maintain clearer, more consistent calculation and reporting of load ratios. ; 3.3 It should be acknowledged that, while component load ratios are fairly straightforward to calculate, they are of limited value for estimating system load ratios. System load ratios are usually desired for field applications, but are more difficult to calculate accurately.; SCOPE; 1.1 This guide covers the general concept of determining safety factors for technical rescue equipment and systems. ; 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. ; 1.3 In the event of any conflict between the text of this guide and any references cited, the text of this guide takes preference. ; 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. ; 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

• Status: Published
• Publication Date: 31-Mar-2020
• ICS: 13.220.10 - Fire-fighting
• Technical Committee: F32 - Search and Rescue
• Drafting Committee: F32.01 - Equipment, Testing, and Maintenance

• Replaces: ASTM F2491-05(2015) - Standard Guide for Determining Load Ratios for Technical Rescue Systems and Equipment
• Effective Date: 01-Apr-2020

Overview

ASTM F2491-20 is the internationally recognized standard guide for determining safety factors for technical rescue systems and equipment. Developed by ASTM International, this standard provides a consistent method for calculating load ratios and safety factors, contributing to safer design, selection, and use of equipment in technical rescue scenarios. Its primary focus is ensuring clear, uniform calculation and reporting practices for both individual equipment components and complete rescue systems.

Key Topics

1. Load Ratios and Safety Factors

• Component Safety Factor: The ratio between the minimum breaking strength of a component and the load it is intended to support.
• System Safety Factor: The ratio between the weakest calculated point in an interconnected system and the anticipated maximum load.

2. Calculation Principles

• Emphasizes the use of SI units as standard.
• Requires using minimum breaking strength for calculations.
• Recommends that component safety factors specified by users must not be lower than those specified by manufacturers.
• Details the importance of considering environmental, age-related, and rigging factors in estimating system strength and load anticipation.

3. Significance of Clarity and Consistency

• Promotes standardized methods to improve the safety and reliability of rescue operations by reducing ambiguity in safety factor calculations.
• Acknowledges increased calculation difficulty with systems versus components, due to interactions and dynamic factors.

4. User and Manufacturer Responsibilities

• Users must establish adequate safety, health, and environmental practices before applying the standard.
• Manufacturers should provide minimum breaking strength information for all components used in life safety applications.

Applications

ASTM F2491-20 is widely applied in a variety of technical rescue and safety contexts. Typical applications include:

• Rigging Systems: Establishing safe working loads for ropes, carabiners, anchors, pulleys, and harnesses in rope rescue systems.
• Confined Space Rescue: Applying safety factors when assembling entry/retrieval systems in hazardous environments.
• Urban Search and Rescue (USAR): Assessing equipment performance under unpredictable loads and conditions.
• Training & Operational Planning: Providing rescue teams, safety managers, and engineers a framework to evaluate and document equipment choices and system configurations.

This standard is essential for those who design, inspect, approve, or use rescue systems-ensuring that both component and system-level safety factors are rigorously evaluated and appropriately documented.

Related Standards

Professionals using ASTM F2491-20 may also reference related standards and best practices to ensure comprehensive safety and performance:

• ASTM F1740: Standard Guide for Inspection of Nylon, Polyester, and Polyolefin Webbing Products for Elongation and Strength.
• NFPA 1983: Standard on Life Safety Rope and Equipment for Emergency Services (National Fire Protection Association).
• ISO 22159: Personal Fall-Arrest Systems.
• OSHA Regulations: Particularly those related to confined space and fall protection.

By following ASTM F2491-20, users contribute to a safer, more effective rescue environment and benefit from a unified, evidence-based approach to technical rescue system safety factors. Always ensure the current version of the standard is consulted for the most up-to-date information and requirements.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2491 − 20
Standard Guide for
Determining Safety Factors for Technical Rescue Systems
and Equipment
This standard is issued under the fixed designation F2491; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.5 system, n—a group of components integrally con-
nected for the purpose of accomplishing work.
1.1 This guide covers the general concept of determining
2.1.6 system safety factor, n—the ratio of the load at which
safety factors for technical rescue equipment and systems.
something in the system will fail and the load that is planned
1.2 The values stated in SI units are to be regarded as
to be applied to the system.
standard. No other units of measurement are included in this
2.1.7 user, n—a person, agency, or representative who has
standard.
authority to make safety-related decisions for rescue applica-
1.3 In the event of any conflict between the text of this guide
tions as discussed herein.
and any references cited, the text of this guide takes preference.
1.4 This standard does not purport to address all of the
3. Significance and Use
safety concerns, if any, associated with its use. It is the
3.1 This guide may be used to provide a consistent method
responsibility of the user of this standard to establish appro-
for determining load ratios for technical rescue equipment and
priate safety, health, and environmental practices and deter-
systems.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor- 3.2 Use of this guide will help to maintain clearer, more
dance with internationally recognized principles on standard- consistent calculation and reporting of load ratios.
ization established in the Decision on Principles for the
3.3 It should be acknowledged that, while component load
Development of International Standards, Guides and Recom-
ratios are fairly straightforward to calculate, they are of limited
mendations issued by the World Trade Organization Technical
value for estimating system load ratios. System load ratios are
Barriers to Trade (TBT) Committee.
usually desired for field applications, but are more difficult to
calculate accurately.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
4. Component Safety Factor
2.1.1 component, n—an individual piece of equipment in its
4.1 Component safety factor refers to the ratio between the
usable form, but unconnected and unencumbered by other
breaking strength of the item and the load that the item is
pieces of equipment in a system.
intended to suspend.
2.1.2 force multiplying situation, n—a situation where the
4.2 Various safety factors may be used for different reasons
rigging causes a force on a component to be greater than
for a particular piece of equipment.
caused by the load.
4.2.1 A manufacturer may or may not have a specified
2.1.3 safety factor, n—ratio between a specified breaking
design factor, representing the ratio between the breaking
strength and an anticipated load.
strength of the product and the working load (that is, the load
2.1.4 strength reduction situation, n—a situation where the
that the product is designed to carry on a normal basis).
rigging of the system causes a component to not perform at its
4.2.2 Users of equipment may specify a component safety
minimum breaking strength.An example would be a carabiner
factor for equipment that will help them to maintain system
with tri-axial forces.
safety factors that are acceptable within their own scope.
4.2.3 The component safety factor specified by an equip-
ment user shall be no lower than that specified by the
This guide is under the jurisdiction of ASTM Committee F32 on Search and
manufacturer, if the manufacturer specifies this information.
Rescue and is the direct responsibility of Subcommittee F32.01 on Equipment,
Testing, and Maintenance.
4.3 Component safety factor is applicable only to the
Current edition approved April 1, 2020
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F2491 − 05 (Reapproved 2015) F2491 − 20
Standard Guide for
Determining Load RatiosSafety Factors for Technical
Rescue Systems and Equipment
This standard is issued under the fixed designation F2491; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers the general concept of determining load ratiossafety factors for technical rescue equipment and systems.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 In the event of any conflict between the text of this guide and any references cited, the text of this guide takes preference.
1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all
of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate
safety safety, health, and healthenvironmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
2.1.1 component, n—an individual piece of equipment in its usable form, but unconnected and unencumbered by other pieces
of equipment in a system.
2.1.2 force multiplying situation, n—a situation where the rigging causes a force on a component to be greater than caused by
the load.
2.1.3 load ratio,safety factor, n—ratio between a specified breaking strength and an anticipated load.
2.1.4 strength reduction situation, n—a situation where the rigging of the system causes a component to not perform at its
minimum breaking strength. An example would be a carabiner with tri-axial forces.
2.1.5 system, n—a group of components integrally connected for the purpose of accomplishing work.
2.1.6 system safety factor, n—the ratio of the load at which something in the system will fail and the load that is planned to be
applied to the system.
2.1.7 user, n—a person, agency, or representative who has authority to make safety-related decisions for rescue applications as
discussed herein.
3. Significance and Use
3.1 This guide may be used to provide a consistent method for determining load ratios for technical rescue equipment and
systems.
3.2 Use of this guide will help to maintain clearer, more consistent calculation and reporting of load ratios.
3.3 It should be acknowledged that, while component load ratios are fairly straightforward to calculate, they are of limited value
for estimating system load ratios. System load ratios are usually desired for field applications, but are more difficult to calculate
accurately.
This guide is under the jurisdiction of ASTM Committee F32 on Search and Rescue and is the direct responsibility of Subcommittee F32.01 on Equipment, Testing, and
Maintenance.
Current edition approved Dec. 1, 2015April 1, 2020. Published December 2015June 2020. Originally approved in 2005. Last previous edition approved in 20102015 as
ɛ
F2491–05(2010)F2491–05(2015). 1. DOI: 10.1520/F2491-05R15.10.1520/F2491-20.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2491 − 20
4. Load RatioComponent Safety Factor
4.1 Load ratio Component safety factor refers to the ratio between the breaking strength of the item and the load that the item
is intended to suspend.
4.2 Various load ratiossafety factors may be used for different reasons for a particular piece of equipment.
4.2.1 A manufacturer may or may not have a specified design factor, representing the ratio between the breaking strength of the
product and the working load (that is, the load that the product is design
...