ISO 16840 Wheelchair Seating Arrangement

The “ISO 16840 Wheelchair Seating Arrangement” standard, published by the International Organization for Standardization (ISO), consists of the following sub-sections published under the same title:

The standard “ISO 16840-1 Part 1: Vocabulary, reference axis rule and dimensions for body segments, posture and posture support surfaces” applies to seating arrangements designed to provide posture support in wheelchairs. This standard includes:
A global coordinate system that allows the posture of a person sitting in a wheelchair to be determined and recorded.
Standard terms and definitions used to describe both the posture and anthropometric characteristics of a person in a wheelchair.
Terms and definitions used to describe the dimensions, location, and orientation of seating support surfaces that together form the body support system.

The ISO 16840-1 standard does not specify any method for measuring a person's sitting posture or define terms for dynamic physiological movements (such as flexion or extension).

The standard “ISO 16840-2 Part 2: Determination of physical and mechanical properties of seat cushions designed to manage tissue integrity” describes the apparatus, test methods, and requirements for wheelchair cushions designed to maintain tissue integrity and prevent tissue trauma.

Test conditions simulate symmetrical anatomy and posture and do not represent cushion performance for specific individual users. Loads are designed to represent loads seen below the pelvis of a 50th percentile wheelchair user and are not intended to evaluate the weight capacity of the cushion or characterize the cushion under bariatric loads. It is possible that not all test methods are applicable to current and future cushion technologies. It does not include test methods or requirements for determining the fire resistance of cushions.

The ISO 16840-2 standard describes procedures for measuring the following:

Loaded contour depth and overload deflection: How deeply a mattress deforms under the user's weight and its response to overloads indicates its pressure distribution capacity.
Wrapping properties: The ability of the mat to conform to the shape of the body and reduce peak pressure on bony prominences.
Interface pressure distribution: Mapping pressure points to assess the risk of tissue damage.
Recovery properties: How quickly a cushion returns to its original shape after a load is removed is crucial for dynamic use.
Hysteresis: Energy loss during compression cycles, reflecting a shift in durability and comfort over time.

These tests use standardized loading tools, such as anthropometric indentations that mimic human hips, to simulate real-world conditions.

The standard “ISO 16840-3 Part 3: Determination of static, impact and repetitive load resistance for posture support devices” describes the requirements for static, impact and repetitive load resistance for posture support devices with associated mounting hardware, designed for use with an unspecified wheelchair seating system. This standard provides test methods for determining whether a product meets the minimum performance requirements before being made available for use.

This standard includes test sets for specific posture support devices. The test methods can be used to verify a manufacturer's claims that a product meets the requirements of this standard. This standard does not apply to posture support devices designed to fail under certain static, dynamic, or repetitive loads.

The ISO 16840-3 standard focuses on determining the mechanical strength of posture support devices under three types of loading conditions (static, impact, and repetitive fatigue). While it applies to components such as seat cushions, backrests, pelvic belts, and other supports designed to maintain posture in wheelchairs, its principles can be extended to other seating systems as well.

This standard primarily describes the following tests:

Static load test
Impact load test
Repetitive load (fatigue) test
The standard “ISO 16840-4 Part 4: Seating systems for motor vehicles” describes the design and performance, instructions and warnings, and test methods and requirements for product marking and labeling of seating systems designed for use as forward-facing seats in a motor vehicle when fitted to a manual or motorized wheelchair. This standard evaluates the frontal impact resistance performance of complete seating systems used by adults or children weighing 22 kg or more.

This standard applies only to complete wheelchair seating systems, including fastening hardware, designed for use with a wheelchair base that meets the ISO 7176-19 standard performance requirements and has fastening points for use with four-point, strap-type fasteners.

The test methods described in this standard are:
Dynamic crash test: Simulates frontal collisions using a sled test that applies force to a wheelchair or seating system mounted on a test rig. Measurements include structural integrity and displacement of the user dummy.
Static load test: Evaluates the durability of connection points (e.g., seat-frame connections) under continuous loads.
Compatibility test: Ensures that posture support devices integrate with wheelchair restraint and occupant protection systems without compromising the holding function.
The standard “ISO 16840-6 Part 6: Simulated use of seat cushions and determination of changes in their properties” describes the equipment, test methods, and requirements for creating aging effects in a seat cushion that mimic the effects of aging seen in use. It also provides methods for determining changes in the physical and mechanical properties of seat cushions based on their age and use. This standard offers a range of tests that simulate wear and tear that can be useful for verifying warranty claims and providing information about product, lifespan, and performance limitations associated with product use.

The test methods described in this standard are:

Aging protocols: Standardized cycles equivalent to 1-3 years of use (e.g., 50.000 compressions at 300-500 N), with optional exposure to sweat simulants (according to ISO 16840-11 standard).
Feature assessment: Post-simulation retesting according to ISO 16840-2 standard measures changes in contour depth, hysteresis, and interfacial pressure.
Durability measures: Quantifies degradation, such as a 15% decrease in envelope size after simulated aging.
The ISO 16840-9 Part 9: Clinical interface pressure mapping guidelines for seating standard is designed to guide users in performing tasks that are directly involved in the clinical use of interface pressure mapping or that are synergistic with its use in a comprehensive wheelchair seating assessment.

This standard does not cover other aspects of the clinical evaluation process (e.g., taking a medical history) or the prescribing or treatment process that might result from an evaluation.

This standard represents the latest state of interface pressure mapping experiences in a sitting scenario. Many of the principles addressed can be generalized to, for example, whole-body (in bed) or foot assessments.

The ISO 16840-9 standard emphasizes static posture and anthropometric data, focusing on clinical measurements of wheelchair users while seated in their devices. It is particularly relevant for individuals with limited mobility (e.g., spinal cord injury) who require seating systems for postural support.

ISO 16840-10 Part 10: "Ignition resistance of posture support devices - Requirements and test method" describes the requirements and test methods for evaluating the ignition resistance of integrated or non-integrated components of a wheelchair designed to maintain tissue integrity or provide posture support, against combustion equivalent to a cigarette burn. The electronic ignition source is also a simulation of other potential environmental ignition hazards.

The tests only measure the ignition resistance of the parts being tested, not the flammability of the entire wheelchair. This provides an indication, but it cannot guarantee the ignition behavior of the wheelchair's assembled devices.

ISO 16840-11 Part 11: Determination of the distribution characteristics of sensible perspiration in seat cushions describes a method for determining the distribution characteristics of simulated sensible perspiration exposure in wheelchair seat cushions under test conditions that simulate body load on support surfaces with flat and contoured profiles. The test method is applicable to a wide variety of seat cushion materials and constructions used worldwide.

This testing method aims to determine how the mattress handles a liquid load. It is not intended to determine how the mattress reacts to continuous liquid or vapor release.

ISO 16840-12 Part 12: Characterization of the immersion and wrapping of seat cushions using double hemispherical recesses describes the equipment, test methods, and requirements for characterizing the immersion and wrapping properties of wheelchair seat cushions using recesses equipped with pressure sensors.

This standard expands the characterization of products intended to manage fabric integrity and provides a standard indentation for other wheelchair seating tests. It does not provide information specific to cushion performance for a particular user, nor is it intended to characterize wrapping or plunging under higher loading conditions or to evaluate a cushion's weight capacity.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "ISO 16840 Wheelchair Seating Arrangement" standard.