Sweating Manikin Tests
TPACC’s advanced “Newton” type sweating manikin systems are used to evaluate whole garments systems (or components of garment systems) for heat and moisture management related to garment insulation and breathability. By measuring these values on a human form, garments are able to be evaluated as they would be worn in the field. Effects of fit, garment construction and design (including trapped air layers) are thus accounted for.
For these reasons, manikin heat loss measurements are much better approximations for realistic human heat loss than measurements made on the material system alone. Also, measurements can be calculated for individual zones or groups of zones, thus giving the ability to isolate effects of garment fit, design and layering. In addition, the manikin is articulated and has a movement system designed to emulate the pumping action created by walking.
The manikin consists of several features designed to work together to evaluate clothing comfort and/or heat stress. Housed in a climate-controlled chamber, the manikin surface is divided into separate sections, each of which has its own sweating, heating, and temperature measuring system. With the exception of a small portion of the face, the whole manikin surface continuously sweats.
Using a pump, preheated water is supplied from a reservoir located outside of the environmental chamber. An internal sweat control system distributes moisture to the “sweat glands” distributed 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 gland is individually calibrated and the calibration values are used by the control software to maintain the sweat rate of each body section.
Water exuding from each simulated sweat gland is absorbed by a custom made body suit. This specialty designed suit acts as the manikin’s ‘skin’ during sweating tests. It is form-fitted to the manikin to eliminate air gaps and provides wicking action to evenly distribute moisture across the entire manikin surface.
Continuous temperature control for the various body 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. Temperature controls are adjustable, by the operator, for each heater control.
Insulation and breathability of garment systems are measured following ASTM F 1291 Standard Method for Measuring the Thermal Insulation of Clothing Using a Heated Manikin and ASTM F 2370 Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin, 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.
Since different fabric layers and reinforcements are used in clothing systems, resultant data from sweating manikin tests provide a powerful basis for understanding how to optimize the materials and clothing design to maximize heat loss from the full ensemble.
The sweating thermal manikin is also used in either a dry or sweating state for specialized measurements according the following standards:
- ASTM F 2371 – Standard Test Method for Measuring the Heat Removal Rate of Personal Cooling Systems Using a Sweating Heated Manikin
- ASTM F 1720 – Standard Test Method for Measuring Thermal Insulation of Sleeping Bags Using a Heated Manikin
- ASTM F 2732 – Standard Practice for Determining the Temperature Ratings for Cold Weather Protective Clothing
- ISO 15831 – Clothing. Physiological Effects. Measurement of thermal insulation by means of a thermal manikin
- EN 13537 – Requirements for Sleeping Bags