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BS ISO 9869-1:2014 pdf free

BS ISO 9869-1:2014 pdf free.Thermal insulation – Building elements
The HFM is a transducer giving an electrical signal which is a direct function of the heat flow transmitted through it.
Most HFMs are thin, thermally resistive plates with temperature sensors arranged in such a way that the electrical signal given by the sensors is directly related to the heat flow through the plate (see Figure 1). The essential properties of an HFM are that it should have a low thermal resistance in order to minimize the perturbation caused by the HFM, and a high enough sensitivity to give a sufficiently large signal for the lowest heat flow rates measured. Recent HFMs are very thin, with low thermal resistance, and highly sensitive. If the thermal resistance of the HFM is low enough, the effects of perturbation of the surface heat flow by positioning the HFM is negligible. The heat flow rate is influenced by building elements and the difference between indoor and outdoor temperature. Therefore, HFM with an appropriate sensitivity shall be selected in consideration of these influences (see Annex E).
NOTE More detailed information on the structure and calibration of HFMs can be found in IS0 8301:1991.
Temperature sensors are transducers giving an electrical signal which is a monotonic function of its temperature.
The effects of the heat flow going through the sensor and on other physical quantities, such as stresses, electromagnetic radiation on the signal have to be taken into account (see Clause 5).
Suitable surface temperature sensors (for R- or A-value measurements) are thin thermocouples and flat resistance thermometers. It is possible, for the conductance measurements, for one or several sensors to be incorporated within one side of the HFM, the side which will be in contact with the surface of the element being measured.
Environmental (ambient) temperature sensors (for U-value measurements) shall be chosen according to the temperature to be measured. For example, if the U-value is defined by the ratio of density of heat flow rate to the air temperature difference, air temperature sensors are to be used. These sensors are shielded against solar and thermal radiation and are ventilated. Other sensors may measure the so-called sol-air temperature, the comfort temperature etc. (see Annex A).BS ISO 9869-1 pdf download.

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