ISO 16840-12:2021 PDF

Wheelchair seating — Part 12: Envelopment and immersion characterization of seat cushions using a dual semispherical indenter

First page of standard ISO 16840-12:2021

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Title (English):

ISO 16840-12:2021

Wheelchair seating — Part 12: Envelopment and immersion characterization of seat cushions using a dual semispherical indenter

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 15
Publication date:: November 3, 2021
Edition:: ISO IS 16840 edition 1 version 1
ICS:: 11.180.10

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Description (English):

This document specifies apparatus, test methods, and disclosure requirements for characterization of wheelchair seat cushion immersion and envelopment properties using indenters instrumented with pressure sensors. This document expands the characterization of products intended to manage tissue integrity (ISO 16840‑2) and provides a standardized indenter for other wheelchair seating tests. It does not provide information specific to cushion performance for a particular individual user, nor is it intended to characterize envelopment or immersion under higher loading conditions, nor to assess the weight capacity of a cushion. This document includes a method that is specific to 220 mm and 255 mm indenters. Dimensions are provided for a 380 mm indenter to allow for extension of the method to larger patient simulation.

Technical details

Technical committee: ISO/TC 173/SC 1 - Wheelchairs
SKU: ISO 16840-12:2021

Abstract

Overview

ISO 16840-12:2021 - Wheelchair seating, Part 12: Envelopment and immersion characterization of seat cushions using a dual semispherical indenter - defines apparatus, test methods and disclosure requirements to quantify how wheelchair seat cushions envelop and allow immersion of body shapes using instrumented indenters. The standard specifies a dual semispherical indenter with embedded pressure sensors, test setups, loading protocols, calculations (envelopment and immersion), and reporting requirements. It supports characterization of cushions intended to manage tissue integrity and provides a standardized indenter for other wheelchair-seating tests.

Key topics and requirements

Scope and limitations
- Characterizes immersion and envelopment properties for typical user sizes; not intended to predict performance for an individual user, to assess weight capacity, or to characterize behavior under higher loading conditions.
- Methods specific to 220 mm and 255 mm indenters; dimensions provided for a 380 mm indenter for larger simulations.
Indenter construction
- Dual semispherical indenter made from rigid material (e.g., hardwood) with specified surface finish (approximate N7) and dimensional tolerances (±0.5 mm).
- Components include trochanter bar, trochanter blocks, semispherical halves and sensor locations at multiple elevations to simulate ischial tuberosities and greater trochanters.
Instrumentation
- Requirements for pressure sensors, timer, loading equipment and a rigid support board.
- Sensors positioned to record pressure across elevations; sensing surfaces flush with the indenter surface.
Test method
- Procedures for cushion preparation, preconditioning, setting datum heights, thickness measurement, load application and data collection.
- Defined calculations for envelopment (contact area or conformity) and immersion (penetration depth relative to a datum).
Reporting and quality
- Test report content requirements and guidance on estimating measurement uncertainty (informative Annex A).

Applications and users

Who uses it
- Cushion designers and manufacturers validating immersion/envelopment design features.
- Clinical researchers and rehabilitation engineers comparing cushion constructions (foam, fluid, hybrid) for tissue integrity performance.
- Test labs and standards bodies conducting repeatable, comparable cushion evaluations.
Practical applications
- Quantifying how a cushion redistributes pressure and conforms to buttock geometry.
- Comparing products intended to reduce pressure-related tissue damage and inform product development, QA and marketing claims (within the scope limits).

Related standards

ISO 16840 series (wheelchair seating) - this part complements ISO 16840-2 (products intended to manage tissue integrity).
ISO 1302 - referenced for surface texture specification.

Keywords: ISO 16840-12:2021, wheelchair seating, cushion testing, indenter, envelopment, immersion, pressure sensors, trochanter, tissue integrity.

Related standards

Mentioned in the description and other ISO standards

Abstract

Overview

Key topics and requirements

Scope and limitations
- Characterizes immersion and envelopment properties for typical user sizes; not intended to predict performance for an individual user, to assess weight capacity, or to characterize behavior under higher loading conditions.
- Methods specific to 220 mm and 255 mm indenters; dimensions provided for a 380 mm indenter for larger simulations.
Indenter construction
- Dual semispherical indenter made from rigid material (e.g., hardwood) with specified surface finish (approximate N7) and dimensional tolerances (±0.5 mm).
- Components include trochanter bar, trochanter blocks, semispherical halves and sensor locations at multiple elevations to simulate ischial tuberosities and greater trochanters.
Instrumentation
- Requirements for pressure sensors, timer, loading equipment and a rigid support board.
- Sensors positioned to record pressure across elevations; sensing surfaces flush with the indenter surface.
Test method
- Procedures for cushion preparation, preconditioning, setting datum heights, thickness measurement, load application and data collection.
- Defined calculations for envelopment (contact area or conformity) and immersion (penetration depth relative to a datum).
Reporting and quality
- Test report content requirements and guidance on estimating measurement uncertainty (informative Annex A).

Applications and users

Who uses it
- Cushion designers and manufacturers validating immersion/envelopment design features.
- Clinical researchers and rehabilitation engineers comparing cushion constructions (foam, fluid, hybrid) for tissue integrity performance.
- Test labs and standards bodies conducting repeatable, comparable cushion evaluations.
Practical applications
- Quantifying how a cushion redistributes pressure and conforms to buttock geometry.
- Comparing products intended to reduce pressure-related tissue damage and inform product development, QA and marketing claims (within the scope limits).

Related standards

ISO 16840 series (wheelchair seating) - this part complements ISO 16840-2 (products intended to manage tissue integrity).
ISO 1302 - referenced for surface texture specification.

Keywords: ISO 16840-12:2021, wheelchair seating, cushion testing, indenter, envelopment, immersion, pressure sensors, trochanter, tissue integrity.

ISO 16840-12:2021 PDF

Technical details

Abstract

Overview

Key topics and requirements

Applications and users

Related standards

Related standards

Abstract

Overview

Key topics and requirements

Applications and users

Related standards

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