LOGSTOR ROR A/S, DENMARK / AREA SALES MANAGER of moisture in the insulation, making repairs possible before serious damage has occurred. The technique of the surveillance system is based on embedded, not insulated copper wires. The alarm system records the electric conductivity of the insulation on an ongoing basis. lf moisture penetrates into the insulation, the conductivity increases and a signal is transmitted. Additionally, the alarm system has an integrated function to ensure that the detection system is intact at all time. A signal is transmitted if the electric circuit is disrupted e.g. if the alarm wire is broken. Conclusion District heating distribution systems have developed from the traditional pipe systems insulated with cellular concrete or mineral wool, to modern pre-insulated pipes with insulation material of polyuretane foam and polyethylene jacket pipe. in addition to excellent insulation properties, modern pre-insulated pipe systems have an important emphasis on safety in the systems. A well-developed joint philosophy ensures a high degree of safety in the pipe assemblies. Furthermore, the systems can be monitored to ensure that no moisture penetrates into the insulation foam and thereby deteriorates the insulation properties. When considering the options for renovating existing pipe systems or establishing new distribution networks, the following expenses and savings should be evaluated: □ District heating distribution systems have developed from the traditional pipe systems insulated with cellular concrete or mineral wool, to modern pre-insulated pipes with insulation material of polyuretane foam and polyethylene jacket pipe. in addition to excellent insulation properties, modern pre-insulated pipe systems have an important emphasis on safety in the systems. A well-developed joint philosophy ensures a high degree of safety in the pipe assemblies. 4 2 � ECOGEtmATION WORLO □ Repair Savings Traditional systems have a relatively high damage frequency compared to pre-insulated pipe systems. After 15 years of operation, the damage frequency will rise due to corrosion problems of the systems, while well-operated pre-insulated pipe systems have a service life of 30 years. it is also worth noticing that repair works of underground pipe systems often are an expensive task, due to traffic regulations, excavation costs, repair costs and finally re-establishment costs. Reduced Water Loss The reduced water loss directly results in savings of operating costs. Experience shows that it may lake many days to find a leak in a traditional system. in average, the water loss is approximately 3-5 m3 of heated and treated water per day. Reduced Heat Loss The actual saving is dependent on the dimensions of the pipes, as the heat loss will increase with increasing pipe dimension. However, the heat loss reduction will typically at least be 2530% when choosing pre-insulated pipes instead of traditional systems. The heat loss savings will result in saved fuel as the lost heat now will be led directly to the consumers. Additionally, reduced heat loss might offer the possibility of reducing the flow temperature of the system without affecting the temperature level at the consumer. References: [1] District Heating Handbook EuHP, European District Heating Pipe Manufacturers Association 1997 Peter Randl0v, Ramb0I ISBN 87-90488-00-8 [2] The Long-term lnsulation Properties of Continuously Produced PUR lnsulated Pipes. Christian Ting-Larsen, Technical Manager, L0gst0r R0r NS. [3] Long-term lnsulation Properties of Pre-insulated District Heating Pipes Henning D. Smidt & J0rgen Daugaard Euroheat & Power, Fernvarme lnternational 4-5/1997 [4] lnspirationsskrift til fjernvarmevrerker med ledningsnet 1 betonkanaler. L0gst0r R0r NS [5] EN 253 - Pre-insulated Pipes for District Heating. Pipe Systems of Steel Pipe, Polyurethane Foam and Jacket Pipes of Polyethylene. 2nd Edition 1994 [6] KMR Schadensstatistik 1998 Heiko von Brunn & Siegfried Finkbeiner Euroheat & Power, Fernvarme lnternational 4-5/1999
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