Sweating manikins. Guarded sweating hot plates measure heat loss only through flat swatches of clothing materials. Sweating manikins are used to measure the heat loss and breathability of full-scale PPE clothing systems. The sweating manikin measures insulation, evaporative resistance, and heat loss using the same principles as the sweating guarded hot plate that is used for both THL and Ret. The difference is that the sweating manikin has a human form that accounts for the air layer between garments and the human body, reinforcements, garment design, and fit. The manikin form consists of 22 separately heated zones. Moisture brought to the manikin’s surface causes it to “sweat,” enabling measurement of a garment’s ability to dissipate evaporative heat. The Newton type manikin is 175 cm in height, with a skin surface area of 1.8 m2, to simulate an adult male. It has 134 sweating holes evenly distributed over the manikin surface.
Sweating manikins are used to measure garment insulation and evaporative resistance according to ASTM FI291, Standard Test Method for Measuring the Thermal Insulation of Clothing Using a Heated Manikin, and ASTM F2370, Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin. Both dynamic and static tests can be conducted of clothing breathability. Dynamic tests involve using an external mechanical drive to “walk the manikin” to create forced convection through body motion. Dynamic manikin tests typically produce larger heat loss through both evaporative heat transfer and dry heat transfer than static manikin tests.
Evaluating heat loss through firefighting elements (gloves, boots, and hoods). Sweating thermal body form instrumentations (hand, foot, and head) is designed to evaluate heat and moisture management properties of glove, boot, and hood systems (Figure B8). These instruments simulate heat and sweat production, making it possible to assess the influence of ensemble elements on the thermal comfort properties for a given environment. Simultaneous heat and moisture transport through the various element systems and variations in these properties over different areas of the body form can be quantified.
The hand, foot, and head manikins operate on the same principles as the sweating manikin system. They consist of several features designed to work together to evaluate comfort and/or heatstress. Housed in a climate-controlled chamber, each body form is divided into separate sections or zones, each of which has its own sweating, heating, and temperature measuring system. Using a pump, preheated water is supplied from a reservoir located outside of the environmental chamber. An internal sweat control system distributes moisture to “sweat glands” across the surface of the manikin. Water supplied to the simulated sweat glands is controlled by operator entry of the desired sweat rate. Each sweat zone is individually calibrated, and the calibration values are used by the control software to maintain the sweat rate of each section.
Continuous temperature control for the hand segments is accomplished by a process control unit that uses analog signal inputs from separate resistance temperature detectors (RTDs). These evenly distributed RTDs are used instead of point sensors because they provide temperature measurements in a manner such that all areas are equally weighted. Distributed over an entire section, each RTD is embedded just below the surface and provides an average temperature for each section. Software establishes any discrepancy between temperature set point and the input signal and adjusts power to section heaters as needed.
Insulation and breathability of each ensemble element are measured following procedures for sweating thermal manikin testing adapted for testing of gloves on a hand manikin (ASTM F3426, Standard Method for Measuring the Thermal Insulation of Clothing Items Using a Heated Manikin Body Forms and ASTM F 3672, Standard Method for Measuring the Evaporative Resistance of Clothing Items Using a Heated Manikin Body Forms, respectively).
Heat Loss Potential (W/m2) is calculated for a standard environment by combining both the dry and sweating components of heat loss measured in their respective states.
Heat Loss
Heat Loss Measured on Protective Elements (Hand, Foot, and Head) . Note: Redder, light colors represent lower heat loss.
