Obiettivo THE MEASUREMENT OF AIR INFILTRATION IS NORMALLY DONE BY BRINGING TRACER GAS IN THE BUILDING AND MEASURE THE TRACER GAS LEVEL AS A FUNCTION OF TIME. THE TRACER GAS DETECTION METHOD WHICH IS MOST OFTEN USED, IS INFRARED GAS ANALYSIS. HERE SAMPLES OF AIR ARE TAKEN TO A GAS ANALYSER TO DETERMINE THE AMOUNT OF TRACER GAS. IN LARGE BUILDINGS A LARGE NUMBER OF DETECTION STATIONS IS REQUIRED DUE TO LOCALLY VARYING INFILTRATION, TEMPERATURE GRADIENTS WHICH CAUSE RECIRCULATION OF AIR, BAD MIXING OF THE TRACER GAS ETC. THIS RESULTS IN LONG AND COMPLICATED DUCTING BETWEEN THE SAMPLING STATIONS AND THE CENTRAL GAS ANALYSER. MOREOVER EACH MEASUREMENT TAKES ABOUT 2 MINUTES THIS MEANS FOR THE CASE OF 10 SAMPLING STATIONS THAT EACH STATION IS SERVED ONLY ONCE IN 20 MINUTES. OTHER DETECTION METHODS HAVE THEREFORE BEEN EXPLORED : THE FIRST METHOD DEALS WITH THE ABSORPTION OF LASER LIGHT OF A CERTAIN FREQUENCY BY THE TRACER GAS WHICH IS DETECTED AND COMPARED WITH THE REFERENCE SIGNAL OF A LASER WHICH IS SLIGHTLY DETUNED SO THAT FOR THIS FREQUENCY NO ABSORPTION TAKES PLACE. THIS SYSTEM GIVES THE AVERAGE TRACER GAS CONCENTRATION ALONG THE LASER BEAM. IF THE CONCENTRATION IS INHOMOGENEOUS THIS METHOD CANNOT GIVE DETAILED INFORMATION ON THE CONCENTRATIONS. A ADDITIONAL DRAWBACK IS THE COST OF THE SYSTEM WHICH AMOUNTS TO UKL 50 000. THE SECOND DETECTION METHOD IS A FUEL CELL ANALYTICAL DETECTOR. HERE THE TRACER GAS IS ETHANOL. IT SERVES AS A FUEL IN THE FUEL CELL AND GIVES AN ELECTRICAL CURRENT WHICH IS A MEASURE FOR THE ETHANOL CONCENTRATION IN THE AIR. CONCENTRATIONS AS SMALL AS 1 PPM CAN BE MEASURED. THIS METHOD IS VERY SUITABLE FOR LARGE MULTICELL BUILDINGS. THE TRACER GAS CONCENTRATIONS CAN BE MEASURED RAPIDLY SO THAT MANY DETECTORS CAN BE SERVED IN A VERY SHORT TIME. THE COST OF THIS SYSTEM WAS ABOUT EQUAL TO THAT OF THE INFRARED GAS ANALYSER BUT THE FUEL CELL SYSTEM HAD A NUMBER OF SIGNIFICANT TECHNICAL PROBLEMS. IT WAS THEREFORE CONCLUDED THAT THE CONVENTIONAL INFRARED GAS ANALYSER IS STILL THE BEST CHOICE. AIR TIGHTNESS MEASUREMENTS HAVE BEEN CARRIED OUT IN TWO LARGE BUILDINGS, WITH A SYSTEM OF 30 MEASURING POINTS AND 3 GAS ANALYSERS. Programma(i) PRE-ENNONUC 2C - Energy research and development programme (EEC), 1979-1983 Argomento(i) Data not available Invito a presentare proposte Data not available Meccanismo di finanziamento Data not available Coordinatore Building Services Research and Information Association (BSRIA) Contributo UE Nessun dato Indirizzo Old Bracknell Lane West RG12 7AH Bracknell Regno Unito Mostra sulla mappa Costo totale Nessun dato
