ISO 16840-11:2022

Overview

ISO 16840-11:2022 specifies a laboratory test method to determine the dissipation characteristics of sensible perspiration into wheelchair seat cushions. The standard defines the required test apparatus, controlled test environment, and a repeatable measurement procedure that simulates a single bolus of liquid perspiration between a buttock-shaped indenter and the cushion. The method is intended to evaluate how a cushion and cover system handles a liquid load (sensible perspiration), not continuous vapour release, and is applicable to a wide variety of cushion materials and constructions.

Keywords: ISO 16840-11:2022, wheelchair seating, dissipation characteristics, sensible perspiration, seat cushion test, PRCLI, impedance measurement

Key Topics and Technical Requirements

• Test principle: deliver a discrete liquid bolus and monitor changing electrical impedance at electrodes near the discharge point to infer liquid dissipation into cover and cushion.
• Test apparatus elements:
  • Perspiration Rigid Cushion Loading Indenter (PRCLI) shaped per ISO 16840-2 contours, with temperature control at 35 °C ± 0.1 °C.
  • Discharge mechanism: release 10 ml ± 1 ml of 0.01 % NaCl solution via a 2 mm ± 0.2 mm hole within 1 s.
  • Sensing system: two round stainless-steel electrodes (10–15 mm diameter, ~0.1 mm thick) placed 10 mm ± 1 mm from the discharge hole.
  • Impedance measurement: range 0.001 MΩ to 1.0 MΩ, sampling rate 1 Hz, AC measurement to avoid electrode electrolysis.
• Test environment: 23 °C ± 2 °C and 50 % ± 5 % RH (ISO 554).
• Test procedure highlights:
  • Precondition cushions 24 h in test environment.
  • Apply vertical load 500 N ± 10 N with PRCLI.
  • Start impedance recording at 1 Hz; inject solution after 1 min; continue recording for at least 1 hour (longer if dissipation is slow).
  • Repeat on three identical cushions and report impedance vs time and PRCLI heating power.
• Reporting: includes test conditions, photos, impedance graphs, numerical impedance table, and test lab accreditation details.

Applications and Who Uses It

• Cushion and cover manufacturers: validate product moisture-handling claims and compare designs.
• Testing laboratories and certification bodies: perform standardized tests for product data sheets and procurement.
• Rehabilitation engineers, clinicians, and researchers: understand moisture dissipation behavior as it relates to comfort and skin health (note: ISO states results are not clinically validated to claim prevention of pressure injuries).
• Procurement and quality assurance teams: specify cushions that meet required dissipation performance for specific user needs.

Related Standards

• ISO 16840-2:2018 - referenced for RCLI contour and related cushion physical/mechanical test methods.
• ISO 554 - standard atmospheres for conditioning and testing (temperature and humidity).

This standard supports objective, repeatable evaluation of how wheelchair cushions manage sensible perspiration - a key factor for user comfort and skin integrity assessments in product development and testing.