ASTM F2894-21

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: F2894 − 19 F2894 − 21
Standard Test Method for
Evaluation of Materials, Protective Clothing, and Equipment
for Heat Resistance Using a Hot Air Circulating Oven
This standard is issued under the fixed designation F2894; 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 test method covers quantitative measurements and subjective observations that characterize the performance for
evaluating the heat resistance of materials, protective clothing, and equipment when exposed in a hot air circulating oven.
1.2 This test method is intended to evaluate physical changes in materials, protective clothing, and equipment at a specified heat
exposure.
1.2.1 The specified heat exposure in the hot air circulating oven is a combination of convective heat and radiant heat.
1.3 Materials, protective clothing, and equipment are evaluated for visible changes or subjected to a material property
measurement following a specified heat exposure.
1.3.1 This test method is not to be used for the evaluation of sticking. An acceptable method for evaluating sticking of fabrics is
described in NFPA 1975, Sections 7.2.1 and 8.3. The NFPA 1975 test method evaluates the thermal stability of specimens by
assessing the blocking of folded specimens placed between glass plates, under a specified weight, inside an oven meeting the same
characteristics of the oven used in this test method.
1.4 This test method enables the quantitative measurement of dimensional change that occurs as a result of a specified heat
exposure in a hot air circulating oven.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to
other units that are commonly used for thermal testing.
1.6 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.
NOTE 1—Flame-resistant and heat-resistant materials are described in a range of different standards and meet a range of different requirements. For
materials tested in accordance with this test method, the applicable standard shall be used to establish preconditioning, conditioning, and testing conditions
and requirements.
1.7 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.
This test method is under the jurisdiction of ASTM Committee F23 on Personal Protective Clothing and Equipment and is the direct responsibility of Subcommittee
F23.80 on Flame and Thermal.
Current edition approved April 1, 2019July 15, 2021. Published April 2019August 2021. Originally approved in 2011. Last previous edition approved in 20142019 as
F2894 – 14.F2894 – 19. DOI:10.1520/F2894-19.DOI:10.1520/F2894-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2894 − 21
2. Referenced Documents
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D1776/D1776M Practice for Conditioning and Testing Textiles
D7571 Specification for Retained Sewn Seam Strength After Exposures to Hot Air and Open Flame
E145 Specification for Gravity-Convection and Forced-Ventilation Ovens
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
F1494 Terminology Relating to Protective Clothing
2.2 AATCC Standard:
Test Method 135 Dimensional Changes in Automatic Home Laundering of Woven and Knit Fabrics
2.3 NFPA Standard:
NFPA 1975 Standard on Station/Work Uniforms for Fire and Emergency Services
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, use the following documents: if the terms are related to textiles, refer to
Terminology D123; if the terms are related to protective clothing, refer to Terminology F1494.
3.1.2 convective heat, n—heat transferred by the motion of a fluid.
3.1.3 degradation, n—a deleterious change in one or more properties of a material.
3.1.3.1 Discussion—
In thermal testing of materials, protective clothing, and equipment, degradation is a material response evidenced by a change in
either or both the visual properties and the performance properties of the test specimen.
3.1.3.2 Discussion—
Degradation generally is associated with a chemical composition change that can result in a change in a visual property, for
example, color, or it can result in a change in a performance property including but not limited to strength, hand, flammability,
penetration resistance, water repellency, and air permeability. A test specimen that changes in one property does not necessarily
change in other properties. Evidence of degradation in performance properties usually requires additional measurements related
to properties of specific interest. Discoloration is a visible material response related to degradation. When discoloration is observed,
it shall be reported.
3.1.4 dimensional change, n—a generic term for change in length or width of a specimen subjected to specified conditions.
3.1.4.1 Discussion—
Dimensional change is usually expressed as a percentage of the original dimension. Positive values for dimensional change indicate
growth, while negative values for dimensional change indicate shrinkage.
3.1.5 distortion, n—in thermal testing of equipment, a specimen response evidenced by a change in its original shape.
3.1.5.1 Discussion—
This type of observation is generally applied to equipment items such as protective helmets, and is based on the placement of the
item on a specific holding device placed in the oven, such as a head form, and the measurement of the specimen relative to the
holding device.
3.1.6 functionality, n—in thermal testing of protective clothing and equipment, the continued utility of the test item as determined
by an assessment of its capability to function after the heat exposure in the same manner as before its exposure to heat.
3.1.6.1 Discussion—
This type of assessment is generally applied to items of hardware or to portions of or complete protective clothing and equipment
items.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Association of Textile Chemists and Colorists (AATCC), P.O. Box 12215, Research Triangle Park, NC 27709, http://www.aatcc.org.
Available from National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA 02169-7471, http://www.nfpa.org.
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3.1.7 ignition, n—the initiation of combustion.
3.1.8 protective clothing, n—an item of clothing that is specifically designed and constructed for the intended purpose of isolating
all or part of the body from a potential hazard; or, isolating the external environment from contamination by the wearer of the
clothing.
3.1.9 protective equipment, n—a non-clothing item of equipment that is specifically designed and constructed for the intended
purpose of isolating all or part of the body from a potential hazard; or, isolating the external environment from contamination by
the user of the equipment.
3.1.10 radiant heat, n—heat communicated by energy propagated through space and transmitted by electromagnetic waves.
3.2 Definitions of Terms Related to Thermal Testing of Materials, Protective Clothing, and Equipment:
3.2.1 deformation, n—in thermal testing of materials, protective clothing, and equipment, a material response evidenced by a
change in shape of the test specimen that is irreversible at room temperature.
3.2.1.1 Discussion—
A change in shape caused by the specified heat exposure such as distortion of woven or non-woven fabrics or curling of knit fabrics
shall not be identified as deformation as long as these changes are reversible at room temperature.
3.2.2 delamination, n—in thermal testing of materials, protective clothing, and equipment, a material response evidenced by the
separation of two of more layers of the test specimen in whole or in part.
3.2.3 dripping, n—in thermal testing of materials, protective clothing, and equipment, a response evidenced by flowing of the
polymer and by the formation of droplets from the flowing material.
3.2.4 flaking, n—in thermal testing of materials, protective clothing, and equipment, a material response evidenced by the
unassisted loss of visible particles of material from the test specimen when the test specimen is removed from the oven for
inspection.
3.2.4.1 Discussion—
The specimen shall not be abraded, flexed, or impacted to generate flaking.
3.2.5 hole formation, n—in thermal testing of materials, protective clothing, and equipment, the appearance of a visible aperture
during the test exposure.
3.2.5.1 Discussion—
The specimen is considered to exhibit hole formation when a visible hole is produced as a result of the thermal exposure that is
approximately 3 mm (0.12 in.) in diameter or greater, or if the hole is rectangular in shape approximately 3 mm (0.12 in.) in width
and length or greater. Single threads across the hole do not reduce the size of the hole for the purposes of this test method.
3.2.6 melting, n—in thermal testing of materials, protective clothing, and equipment, the liquefaction of material under the
influence of heat.
3.2.6.1 Discussion—
Melting is determined visually by a change in the material physical appearance such as fusing of fibers or the evidence of material
flowing.
3.2.7 separation, n—in thermal testing of materials, protective clothing, and equipment, a material response evidenced by splitting
or delaminating.
3.2.8 splitting, n—in thermal testing of materials, protective clothing, and equipment, a material response evidenced by the test
specimen breaking into two or more pieces in whole or in part.
4. Summary of Test Method
4.1 The test method evaluates the heat resistance of materials, protective clothing, and equipment using a hot air circulating oven.
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4.2 Specimens shall be exposed in the test oven at a specified temperature for a specified oven exposure time as required by the
applicable material or product specification.
4.2.1 If no material or end product specification requirements for the oven temperature and oven exposure time are provided, the
oven temperature shall be 260 +8/–0 °C (500 +14/–0 °F) and the oven exposure time shall be 5 min +15/–0 s.
4.3 Following heat exposure, the test specimen is removed and examined for evidence of one or more of the following phenomena:
ignition, melting, dripping, separation, etc.; see 11.5.
4.4 If specified, test specimens are evaluated for dimensional change as a result of the convective heat exposure.
5. Significance and Use
5.1 This test method is used to evaluate the heat resistance of materials, clothing, and equipment when exposed to heat in a hot
air circulating oven. The principal findings of this test method are observations of the specimen response to the heat exposure.
5.1.1 The majority of procedures specified in this test method apply to the evaluation of flat material specimens.
5.1.2 When evaluating non-flat materials, alternative procedures are required for mounting specimens and interpreting the effects
of the heat exposure.
5.2 If specified, this test method is used for the measurement of material dimensional change following a convective heat exposure
in a hot air circulating oven.
5.3 This test method is not intended to simulate the actual exposure of material, clothing, or equipment in high-heat conditions
such as a fire environment.
6. Apparatus
6.1 Test Oven—The test oven shall be a horizontal-flow circulating oven with minimum interior dimensions of 610 mm by 610
mm by 610 mm such that a specimen can be suspended and be positioned at least 50 mm (2 in.) from any interior oven surface
or other specimen.
6.1.1 The test oven shall have an air velocity of 0.5 to 1.5 m ⁄s at the standard temperature and pressure of 21 °C at local
atmospheric pressure,ambient temperature and atmospheric pressure, with the heating elements off, measured at the geometric
center point of the oven.
6.1.2 The test oven shall be equipped with an oven-sensing thermocouple which is used as part of the oven temperature control
mechanism.
6.1.2.1 The oven-sensing thermocouple shall be positioned so that it is level with the horizontal centerline of a mounted sample
specimen, and the oven-sensing thermocouple shall be equidistant between the vertical centerline of a mounted specimen
positioned in the middle of the oven and the oven wall where the airflow enters the oven test chamber.
6.1.2.2 The oven-sensing thermocouple shall be an exposed bead, Type J or Type K, No. 30 AWG thermocouple.
6.2 Specimen Mounting—Metal hooks or clamps shall be used to suspend the specimens in the oven.
6.2.1 If the specimens are too large to be suspended, a suitable insulating form shall be placed in the center of the oven and the
specimen shall rest on the insulating form. Ceramic has been found to be an effective material for this form.
6.2.2 In the testing of some items, such as individual pieces of hardware, loops of heat-resistant thread are used to suspend the
specimen.
3 1
6.3 Optional Stretching Frame—The optional stretching frame, Fig. 1, consists of a rigid board, 9.5 6 3 mm ( ⁄8 6 ⁄8 in.) thick,
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FIG. 1 Schematic of Optional Stretching Frame for Knit Material Specimens
with uniformly spaced pins along the perimeter at intervals of 25 6 3 mm (1 6 ⁄8 in.) to secure knit materials. The pins shall
3 1
protrude 19 6 3 mm ( ⁄4 6 ⁄8 in.) from the surface of the board, shall have a shank diameter of 2.5 6 0.5 mm (0.1 6 0.02 in.),
and shall be drawn to a sharply pointed tip. Construct the stretching frame with a length and width at least large enough to
accommodate the test specimen size specified in 9.1.1 and 9.1.2 so that the pins are located 38 6 12.5 mm (1.5 6 0.5 in.) inward
from the edges of the test specimen.
6.3.1 The optional stretching frame is permitted to be used before the knit specimen is placed in the oven for marking the specimen
for dimensional change determination. The stretching frame is not used while the knit specimen is exposed in the oven. The
optional stretching frame is also permitted to be used for a specified period of time after heat exposure in the oven to return knit
specimens to their original dimensions. See 9.3.1 and 11.6.1.
7. Hazards
7.1 Normal precautions shall be taken for working around hot surfaces and flaming, melting, or dripping test specimens.
7.2 The oven shall be properly vented to ensure that harmful vapors and gases are evacuated from the laboratory.
7.3 Special care shall be exercised when using the optional stretching frame. The optional stretching frame contains a series of
sharp pins, which have the potential to present a puncture hazard when not handled properly.
8. Preconditioning of Test Samples
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8.1 Material samples not obtained from garments for preconditioning shall be at least 1 m (1.2 yd ) to ensure sufficient material
for the test specimen size requirements in 9.1.1 and 9.1.2. The material sample shall be representative of the material utilized in
the construction of the protective clothing end product.
8.1.1 If the material width is less than 1 m (1.1 yd), the sample shall be the full width of the material, and the length of the sample
shall be sufficient to meet the test specimen size requirements of 9.1.1 or 9.1.2.
8.1.2 Precondition samples of protective clothing as complete items.
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8.1.3 Precondition samples of protective equipment as complete items.
8.2 Precondition samples as required by the applicable material or end product specification.
8.2.1 If no mat
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