Describes a small calibrated hotbox, developed at Lawrence Berkeley Laboratory for studying methods of improving window performance. Describes the construction and calibration of the box. Discusses measurements of thermal conductance made with the box. Finds the hotbox is reliable with known skin losses and free of systematic errors to at least the 7% level.
Describes some of the problems encountered when the full-scale wind pressure measuring system was set up in an experimental building at the University of Hong Kong. Discusses effects such as excessive damping caused by the air trapped in the pressure- balancing tubings, and the interference between transducers. Describes modifications of the measuring system to overcome these problems.
Considers that air change measurement by means of tracer gas is the best way of measuring natural air infiltration in buildings. In some cases the method can be useful for measuring the ventilating air rate in mechanical systems asno interference with the system is required by the method. Deals with the theory of the method, the handling and measurement of different gases, cost of gas and instruments. Concludes by saying that only very simple instrumentation is required for most of the measurements with satisfactory accuracy.
An anemometer which was developed for indoor climate research has been modified in order to get the same shape of calibration curve for each anemometer. Experiments in a wind tunnel showed that this was the case for more than 80% of a test series of the modified anemometers. The time constant has increased but is still acceptable. Calibration curves and time constants could be predicted by calculation with reasonable accuracy. Some influence of dust particles on the instrument was noticed.
Describes the operating characteristics of a small aspirated concentration sensor based on a hot-film anemometer. Constant aspiration velocity past the sensor produces a linear output over a wide range of tracer gas concentrations, and a useful bandwidth of 0-500 Hz. A simple experimental technique for dynamic calibration is presented, with frequency response inferred from a model of the effects of molecular diffusion and hot-film response.
An automated air infiltration measurement system for large buildings isdescribed. The system consists of a micro-computer, electron capture gaschromatograph, a ten port sampling manifold, and five tracer gas injectionunits. The system controls the injection and sampling of tracer gas in amulti-zone building, calculates the air infiltration rates of each zone, andmeasures the on-time of events such as HVAC fan operation, exhaust fan operation,and door/window openings.
Describes the development of an anemometer for the measurement of rapidly fluctuating air flows. Describes the B.R.E. shielded hot wire anemometer. Discusses modifications made to this anemometer to improve its response by using different shields and moving sensor wires closer together. Outlines system for processing signals from the anemometer using a micro-computer. Gives results of performance tests. Gives simple applications of theinstrument.
Reports tests of a scintillation counter to detect Ra 222 in air and water. The counter consists of a spherical cavity coated with ZnS(Ag) powder, built in a lucite cylinder whose external surfaces, excepting the window which is put in contact with a photomultiplier, are made reflective with a special paint. The performance of the detector has been analysed with respect to size,efficiency, background, constant activity and constant concentration in the sample. Finds that for liquid samples, two different values for the diameter, 5 cm. and 7.5 cm.
Reports study of the emanating power of radon from building materials. Samples of material were placed in an air-tight glass container and the radon diffusing from the sample was measured in an electrostatically operated cylindrical steel chamber in which alpha particle scintillations were counted.< Gives main results for different building materials in the form of anemanation coefficient, defined as the ratio of migrating 222Rn to the 226Ra content in the sample. Materials tested were fly-ash, slag, by-product gypsum, red brick, silicon brick, portland cement, and soil.
Describes a method of measuring airborne concentrations of radon daughters which distinguishes between the different isotopes. At the place of sampling, air is flowed through a millipore filter for five to ten minutes at approximately 12 litres per minute. The filter is counted during the period 2 to 12 minutes post sampling; the counts are integrated over each of four regions of energy and a second count made for the same regions during the period 15 to 30 minutes post sampling. Results are analysed by a BASIC computer program.
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