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Field Test of Tracer Gas Method for Measurement of the Transfer of Compounds between Dry Cleaning Establishments and Adjacent Appartments English summaryThis project is the second phase in the development of a diffusive tracer gas method for measurement of compound transfer and air movement between adjacent rooms in a building. The method’s primary objective is application for assessment of the impacts from a dry-cleaning establishments’ operation to a superjacent apartment; however, the method will also be usable in other contexts. Collection and analytical methods were developed and the method’s performance was tested under laboratory conditions during the initial phase of the project (The Danish Environmental Protection Agency 2002a). The aim with the second phase is to test the method under realistic conditions in the field and to collect the first information on the extent of air transfer between a dry cleaning establishment and a superjacent apartment. Determination of tracer gasses and cleaning fluids’ diffusion velocity through an intact concrete slab was conducted as part of the method testing. A difference of approximately 50% was noted when the tracer gasses PP2 and PP3 were compared with tetrachloroethylene and 30% when the comparison was made in relation to a hydrocarbon (decane). The laboratory tests also indicate that up to 30% of tracer gas as well tetrachloroethylene are deposited in the concrete slab. The liberation of decane (hydrocarbon) was up to 60%. However, the field tests indicated that the diffusive transport composed an insignificant contribution to the total compound transfer between the dry-cleaning establishment and the apartment. Therefore suggested that there no compensation is necessary for differences in the diffusion velocity or adsorption when calculating the transfer of contaminations between the dry cleaning establishment and the apartment on the basis of tracer gas concentrations. If the diffusive contribution at any given time is more significant as regards interior requirements for the dry-cleaning establishment, this item should be reassessed. Tetrachloroethylene diffused through the concrete slab with a velocity more than 50% greater than the tracer gasses. Correspondingly the diffusion velocity for the applied hydrocarbon (decane) was approximately 30% less than the corresponding tracer gasses. Furthermore, the laboratory tests indicated that the transfer through the concrete slab was very speedy and gave rise to a situation where stationary transfer through a floor would adjust quickly. This caused an assessment that one could set up samplers a few days after setting-up tracer gas sources at field measurements. The field tests were carried out at three locations in the Copenhagen area. The testing stations were selected where, as far as possible there was no diffusion through any media other than the floor. This was done e.g. to ensure that there was no traffic between the dry cleaning establishment and the apartment through internal stairs. The test locations were also selected because no or limited preventive measures were taken at the time of the test, such as sealing visible open lead pipes to avoid diffusion to the superjacent apartment. Thus diffusion-tight membranes or low-pressure ventilated ceilings were not mounted in any of the locations. Two tracer gasses designated PP2 and PP3I were used in the tests. Tracer gas sources were mounted at three places in the dry-cleaning establishment and the superjacent apartment respectively. A number of samplers were placed two days after mounting the tracer gas sources in the dry-cleaning establishment, as well as the apartment. Samplers were mounted in six and twelve positions in the dry cleaning establishment and the apartment respectively in order to assess the vertical and horizontal variations in the tracer gas concentration. Measurement results indicated that the tracer gas diffused evenly in the locations and that the extent of the measurement positions could be reduced in future. A total of 55 double determinations were carried out during the test period. Analysis of the results shows an excellent method repeatability (sampling and analysis) corresponding to a relative standard deviation of 8% on the double determinations. Uncertainty of the calculated flux is estimated at 25%. The initial measurement results of the compound transfer between the dry cleaning establishment and the apartment showed that there might be considerable variations between measurements within short time. Thus variations of 3-5 times were found when the measurements over 14 days were carried out at 14-day intervals in the same location. The cause is presumably due to outside climatic conditions that influence the air movements in the building. It has proved impossible to obtain tests of the variation in air movements between storeys; however, experience from the Danish Building Research Institute ("By og Byg ") and Risø research facility indicates that these are not unrealistic variations. It is most likely that future interior requirements at the cleaning establishments, such as mounting of diffusive tight membranes or low-pressure ventilated ceilings, will reduce the time-related variation. The method allows direct measurement and calculation of the actual transfer of contamination between a dry-cleaning establishment and an apartment. The extent of this contribution to the apartment’s space concentration of cleaning fluid vapours is inversely proportional with the actual air change in the apartment above the dry-cleaning establishment. The following is suggested: When applying the method at future measurements, building code requirements of an air change of 0.5 times per hour should be used as a common calculation and assessment basis for apartments in multi-storey buildings. Thus the measurement method developed seems to be successfully applicable under realistic conditions for assessing the dispersion of contamination from a dry-cleaning establishment to a superjacent apartment. When assessing the results note that the measurements are for single points in time (over a period of 14 days) and that there may be significant time-related variations. The test results were used to determine the test circumstances for future application of the method: Samplers could be mounted 48 hours after placing the tracer gas sources in the dry-cleaning establishment and the apartment. Three tracer gas sources were used for the tests in the dry cleaning establishment and the apartment. This number should be maintained in future use of the method. Furthermore, in future use it is recommended that the samplers be placed evenly dispersed with four in the dry-cleaning establishment and three in the apartment – all 1.7 m over the floor. Sampler and tracer gas sources must be placed allowing free air movement to pass. Placement in corners should therefore be avoided. In connection with the project’s forthcoming third phase, supplementing the tracer gas measurements with simultaneous measurements for cleaning fluid vapours in dry-cleaning establishments and apartments should be considered, partly to enhance the results of the method, and partly to gather more information as the extent of internal contribution in apartments
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