Protective Clothing Testing

Aerosol Challenge Test Capabilities

Wind tunnel aerosol facility for protective garment research and testing
Wind tunnel aerosol facility for protective garment research and testing

RTI offers extensive and unique capabilities to support aerosol challenge research and testing of chemical protective fabrics and ensembles.

  • Recognized leadership and expertise in aerosol challenge tests of protective garments. RTI developed the aerosol systems and swatch test methodologies now specified for aerosol challenge tests by the Department of Defense (DoD) and the National Fire Protection Association (NFPA).
  • Full-scale aerosol exposure chamber/wind tunnel for human-subject testing of chemical protective ensembles under controlled temperature, relative humidity, wind speed, and aerosol conditions. Direct quantification of aerosol deposition on skin and clothing.
  • DoD TOP 10-2-022 and NFPA 1994 Class 4 particle inward leakage test.
  • Swatch test apparatus for the aerosol challenge of fabric samples. Operates at controlled temperature and humidity conditions (typically 90°F and 60% RH), constant 0.1 inch H2O pressure drop and constant face velocity modes.
  • Capability to generate and measure a wide range of fluorescently tagged challenge aerosols.
  • Separate bioaerosol test facilities where fabric samples can be evaluated.

Full-Scale Testing of Chemical Protective Garments

Full-scale aerosol challenge tests of military and first responder protective garments are performed in RTI's wind tunnel aerosol exposure facility. The open-jet recirculating wind tunnel contains a 7-ft diameter, 40-hp vane-axial fan centrally located in a 28-ft x 50-ft sealed room. Wind speeds up to 40 mph may be achieved within the 6-ft diameter test section. Upon exiting the test section, the air freely expands into the room and recirculates back to the fan intake. To facilitate operations, the test section is mounted on a raised platform providing access from below; overhead access is also available. Adjoining the wind tunnel are control room, doffing area, and sampling room. Donning and garment storage areas are located apart from the wind tunnel.

To allow for testing over a range of ambient conditions, the wind tunnel is equipped with cooling, heating, and humidity controls. Temperatures from approximately 0 to 45°C and relative humidities from approximately 20% to 85% may be achieved. The ventilation systems of the wind tunnel include a recirculating, high-efficiency filtration system for the removal of aerosol from the wind tunnel atmosphere and an ambient air purging system.

Aerosol Preparation and Generation

RTI has extensive expertise in the preparation and analysis of solid and liquid phase fluorescently tagged challenge aerosols to support protective garment research and testing. The use of fluorescent tracers allows accurate measurement of aerosol deposition on skin and clothing and minimizes background interference (e.g., from ambient aerosol, shed clothing fibers, and carbon dust).

Aerosol Swatch Testing

Preparing a fabric sample for an aerosol swatch test
Preparing a fabric sample
for an aerosol swatch test

RTI offers a quality-built, dedicated test apparatus for measuring the aerosol penetration of fabric swatches (see sample report) over the particle diameter size range from 10 – 5,000 nm (0.01 to 5 µm). The system is constructed of polished stainless steel (providing a smooth static-free duct), is temperature and humidity controlled for operation over a wide range of conditions (typically 90°F and 60% RH), and is designed to operate in both constant pressure drop (e.g., 0.1 inch H2O) and constant face velocity modes.

The challenge aerosol is either oil or salt generated with a nebulizer or nanometer silica generated by high-temperature reaction. Aerosol concentration measurements are made with a scanning mobility particle sizer (SMPS) or a high-resolution optical particle counter (OPC) depending on the particle size range of interest. Flow rate through the swatch is measured with a laminar flow element and the pressure drop is measured with a micromanometer.