CONDENSATION CONTROL The following technical characteristics are applicable when considering the right thermal and acoustic insulation products for HVAC-R, process and industrial pipe and ductwork systems: Thermal conductivity is a key characteristic of insulation and is a property of the material itself - independent of the material thickness. Thermal conductivity is stated in W/(m • K) and measures the heat in joules which, per unit of time, flows through 1m3 of a material (heat flow density). This is measured at a temperature difference of 1K and denotes the property of a material's ability to conduct heat. At a given temperature and relative humidity, air contains a defined amount of water vapour. When air begins to cool water vapour starts to condense and eventually reaches 100% saturation - known as the ‘dew point’ temperature. The higher the humidity level, the sooner the point of saturation is reached, even if the air only cools by a small amount. When the dew point is reached moisture is released in the form of droplets as it makes contact with cold surfaces. For this reason pipework and services operating at below-ambient temperatures attract condensation. So whereas hot installations (heating and hot-water pipes) are mainly insulated to save energy, cold systems (such as the chilled-water pipes of air-conditioning systems or the suction lines of commercial freezers) principally need protection against condensation. To prevent condensation, the insulation thicknesses used on cold pipes must be sufficient to ensure that the temperature on the surface of the insulation material never falls below the dew point. When selecting and determining the thickness of low-temperature insulation, it is also necessary to bear in mind that over the equipment service life, energy losses can increase dramatically as a result of moisture penetration. Technical considerations THERMAL CONDUCTIVITY A reliable insulation system must therefore provide protection against moisture penetration since with every % volume increase of moisture content, the thermal conductivity of insulation increases and the thermal performance deteriorates. The results are not only higher energy losses, but also a drop in the surface temperature meaning condensation occurs more readily. It is only possible to guarantee that the surface temperature remains above the dew point (even after many years of operation) if the thermal conductivity of the insulation material does not deteriorate as a result of moisture penetration. ArmaFlex materials are perfectly suited to refrigeration and cold applications since the closed cell structure provides an integral vapour barrier against moisture ingress. ArmaFlex does not require any additional vapour barrier due to its high water vapour resistance value of µ ≥10,000 (equivalent to a static air layer 100m wide). For example, a material with a high thermal conductivity, such as copper, has a value of approximately 400 W/(m • K), compared to a low thermal conductivity material such as AF/Armaflex Class O at 0.033 W/(m • K) at 0 °C. The lower a material‘s thermal conductivity value is, the longer it takes heat to transfer through it and the greater the insulative properties. 13