ASTM F2491-05(2015)
(Guide)Standard Guide for Determining Load Ratios for Technical Rescue Systems and Equipment
Standard Guide for Determining Load Ratios for Technical Rescue Systems and Equipment
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 load ratios 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: F2491 − 05 (Reapproved 2015)
Standard Guide for
Determining Load Ratios for Technical Rescue Systems and
1
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 2.1.7 user, n—a person, agency, or representative who has
authority to make safety-related decisions for rescue applica-
1.1 This guide covers the general concept of determining
tions as discussed herein.
load ratios for technical rescue equipment and systems.
3. Significance and Use
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3.1 This guide may be used to provide a consistent method
standard.
for determining load ratios for technical rescue equipment and
systems.
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.
3.2 Use of this guide will help to maintain clearer, more
consistent calculation and reporting of load ratios.
1.4 This standard may involve hazardous materials,
operations, and equipment. This standard does not purport to
3.3 It should be acknowledged that, while component load
address all of the safety concerns, if any, associated with its
ratios are fairly straightforward to calculate, they are of limited
use. It is the responsibility of the user of this standard to
value for estimating system load ratios. System load ratios are
establish appropriate safety and health practices and deter-
usually desired for field applications, but are more difficult to
mine the applicability of regulatory limitations prior to use.
calculate accurately.
4. Load Ratio
2. Terminology
4.1 Load ratio refers to the ratio between the breaking
2.1 Definitions of Terms Specific to This Standard:
strength of the item and the load that the item is intended to
2.1.1 component, n—an individual piece of equipment in its
suspend.
usable form, but unconnected and unencumbered by other
pieces of equipment in a system.
4.2 Various load ratios may be used for different reasons for
a particular piece of equipment.
2.1.2 force multiplying situation, n—a situation where the
4.2.1 A manufacturer may or may not have a specified
rigging causes a force on a component to be greater than
design factor, representing the ratio between the breaking
caused by the load.
strength of the product and the working load (that is, the load
2.1.3 load ratio, n—ratio between a specified breaking
that the product is designed to carry on a normal basis).
strength and an anticipated load.
4.2.2 Users of equipment may specify a load ratio for
2.1.4 strength reduction situation, n—a situation where the
equipment that will help them to maintain system safety factors
rigging of the system causes a component to not perform at its
that are acceptable within their own scope.
minimum breaking strength.An example would be a carabiner
4.2.3 The load ratio specified by an equipment user shall be
with tri-axial forces.
no lower than that specified by the manufacturer, if the
2.1.5 system, n—a group of components integrally con-
manufacturer specifies this information.
nected for the purpose of accomplishing work.
4.3 Load ratio is applicable only to the component, and does
2.1.6 system safety factor, n—the ratio of the load at which
not address how this component affects or is affected by other
something in the system will fail and the load that is planned
components in a system.
to be applied to the system.
4.4 Load ratios, when used, should always be determined
using minimum breaking strength as the foundation (rather
1
This guide is under the jurisdiction of ASTM Committee F32 on Search and
than average or maximum or other)
Rescue and is the direct responsibility of Subcommittee F32.01 on Equipment,
Testing, and Maintenance.
5. System Safety Factor
Current edition approved Dec. 1, 2015. Published December 2015. Originally
ɛ
5.1 System safety factor refers to the ratio between the
approved in 2005. Last previous edition approved in 2010 as F2491–05(2010) 1.
DOI: 10.1520/F2491-05R15. strength of the calculated weakest point in a system and the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
F2491 − 05 (2015)
anticipated load. This is to say that the weak point in a system 5.4.1.3 Directional loading.
is however many times stronger than the load that will be 5.4.1.4 Rigging angles.
placed on the system. 5.4.1.5 Variations in the load mass (that is, a
...
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.
´1
Designation: F2491 − 05 (Reapproved 2010) F2491 − 05 (Reapproved 2015)
Standard Guide for
Determining Load Ratios for Technical Rescue Systems and
1
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
ε NOTE—Editorial changes were made in 1.2, 2.1.6, 5.1, and 5.3.1 in December 2010.
1. Scope
1.1 This guide covers the general concept of determining load ratios 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 and health practices and determine the applicability of regulatory limitations prior to use.
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, 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.
4. Load Ratio
4.1 Load ratio 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 ratios may be used for different reasons for a particular piece of equipment.
1
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, 2010Dec. 1, 2015. Published March 2011December 2015. Originally approved in 2005. Last previous edition approved in 20052010 as
ɛ
F2491F2491–05(2010) –05.1. DOI: 10.1520/F2491-05R10e1.10.1520/F2491-05R15.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
F2491 − 05 (2015)
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 designed to carry on a normal basis).
4.2.2 Users of equipment may specify a load ratio for equipment that will help them to maintain system safety factors that are
acceptable within their own scope.
4.2.3 The load ratio specified by an equipment user shall be no lower than that specified by the manufacturer, if the manufacturer
specifies this information.
4.3 Load ratio is applicable only to the component, and does not address how this component affects or is affected by other
components in a system.
4.4 Load ratios, when used, should always be determined using minimum breaking strength
...
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