With Guarded Hot Pipe
With guarded hot pipe according to DIN EN ISO 8497, ASTM C 534, DIN EN 1946-5
Devices with guarded hot pipe are used by the industry for quality control and monitoring in the area of production as well as by testing and research institutions. Due to the high measuring accuracy they are ideally suited for reference measurements and external quality control.
All TLR devices from TAURUS Instruments use measuring tubes of various diameters with two symmetrically arranged active guard pipes on either end according to EN ISO 8497, section 7.3, figure 1. This method is a direct stationary method during which a power equivalent to the heat flow is supplied to the heating pipe.
Schematic diagram of guarded hot pipe method:
Calculation of thermal conductivity:
The thermal conductivity λ is calculated as follows:
|λ= (U · I · d) / (A · ΔT)||U:
|voltage of heating pipe in [V]
current of heating pipe in [A]
sample thickness in [m]
measuring area in [m²]
temperature difference in [K]
The thermal conductivity lambda is calculated from the electrical power that is supplied to the heating pipe (power = voltage x current), the sample dimensions (thickness, area) and the temperature difference. The result is a material constant that is valid irrespective of the dimensions of the sample. The thermal resistance is the reciprocal of the thermal conductivity (1 / λ).
Field of application:
Determining the thermal conductivity and thermal resistance of pipe insulation materials.