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Review and Evaluation of Thermal Sensors for Use in Testing Firefighters Protective Clothing. Annual Report.


pdf icon Review and Evaluation of Thermal Sensors for Use in Testing Firefighters Protective Clothing. Annual Report. (9614 K)
Barker, R. L.; Hamouda, H.; Shalev, I.; Johnson, J.

NIST GCR 99-773; Annual Report; 72 p. March 1999.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900.
Website: http://www.ntis.gov
Order number: PB99-140527

Keywords:

fire fighters; protective clothing; sensors; turnout coats; heat flux; heat sinks; measuring instruments

Abstract:

The Center for Research on Textile Protection and Comfort (T-PACC) at North Carolina State University conducted a project which had, as its primary objective, the selection and evaluation of sensors that can be used to measure heat transferred through firefighter protective clothing materials, with the ultimate goal of applying this knowledge base to the development of rugged, and dependable laboratory benchtop and fire scene specific sensor technology. The purpose of this final report is to summarize the findings of this project and to recommend future directions in protection measuring heat flux sensor development. Non-cooled sensor technology was initially investigated for this application. A review of state-of-the-art surface heat flux measuring devices confirmed the existence of a variety of sensor options, including devices that utilize buried thermocouple transducers, slug or heat capacitance calorimeters, thin foil or Gordon transducers, wafer type thermocouple transducers and suspended disk thermocouple transducers. Based on stated applications and instrumental needs, four different thermal sensors were selected for comparative testing and evaluation by this program. A fifth sensor called "Pyrocal", built at NCSU, was included in this project in order to address the disadvantages encountered in the available sensors. The Pyrocal sensor is smaller and far less bulky than the TPP calorimeter having less heat loss and more rapid response times. Pyrocal has the additional advantage of possessing a small mass in comparison to the TPP calorimeter (1.3 grams vs. 17.9 grams). This is an important consideration, since the smaller mass of the Pyrocal sensor significantly reduced heat sink effects associated with the use of the TPP calorimeter. This contributed to improve the accuracy of the bench top TPP tests when used in sample mounting configurations that require intimate contact between the thermal sensor and the test fabric. Although other existing non-cooled sensors that utilize surface mounted thermocouples (ThermoMan(r) and Alberta type) performed comparatively well in our thermal tests, they lacked the durability in use that can be expected from the Pyrocal device. Most significantly, the Pyrocal sensor overcomes a significant drawback associated with existing sensors. It does not require an inverse heat transfer calculation to estimate heat flux. This avoids errors associated with thermocouple location, and the mathematics of the heat transfer calculations. Direct heat flux measurements, using the Pyrocal sensor, circumvent these errors and provide a more accurate direct reading.