tracer gas

Describes a photo-electric technique for instant determination of contaminant concentration in wind tunnel studies of stack gas dispersion. A roving sensor is used to measure the light scattered by the particles of oily aerosol representing theprototype stack effluent. The minature probe has a noise level of only one hundred thousandth of the full linear range of the output signal for a time constant of 5s. Device is also suitablefor measurement of fluctuating flow properties, such as turbulence, where a high frequency response is required.

Reports investigation of the relative effectiveness of wall gratings and flues as means of naturally ventilating unheated closed rooms. Ventilation rates of several rooms were measured using carbon dioxide as tracer gas and wind speed and direction were recorded. Presents results and finds for the flue, ventilation increased with wind speed irrespective of direction. For grating, ventilation rate increases slowly with size of grating and is dependent on both wind speed and direction. Concludes flue with base opening of 15 sq.ins. is as efficacious as grating having 50 sq.ins.

Describes the basis of operation of electron absorption detector and the nature and causes of the erroneous and anomalous responses it may generate. Suggests pulse sampling technique asan alternative method of analysis. This retains the sensitivity of the simple low potential ion chamber method, but is substantially free of errors and anomolous responses. Describes the basis of this improved method and gives an account of the technique for its use in quantitative and qualitative analysis.

Reports 312 measurements of ventilation rate in 31 rooms in old and new blocks of flats, 3 villa residences and a modern university building, made using coal gas as a tracer. Describes buildings and gives main results. Examines effect on air change rate of sealing flues and gratings, opening windows and weather conditions. Finds outside wind speed has most influence on ventilation rate. Discusses recommended standards of air supply.

Presents results of measurements of ventilation rate and window air leakage made in blocks of flats in Sweden. Describes measurement of ventilation rate using nitrous oxide as a tracer gas and pressurization tests on windows. Gives graphical results of tests. Finds that the majority of windows do not satisfy 1975swedish building code. Reports measurements of air leakage of windows before and after renewal of draught excluders. Concludes that old windows can be made relatively draught-free and that this is not expensive or time consuming.

Describes method of measuring air flow in mines using nitrous oxide as a tracer gas. Examines two methods of measuring airflow, releasing a continuous stream of a gas and releasing a known quantity of gas. Describes laboratory study andunderground tests of method. Concludes that technique is reliable and accurate.

Gives formula for calculating air-change-rate from decay rate of a tracer gas. Discusses different tracer gases and detecting instruments. Describes portable meter used to measure the concentration of helium. Discusses its performance and describes the experimental procedure.

Reports investigation of air infiltration in two residences using helium as a tracer gas. Describes the residences, instrumentation and test procedure. Gives results of decay rate of tracer gas and measured infiltration rates. Summarizes test conditions in tables of temperature, wind speed and direction, internal to external pressure differences and height of the neutral zone. Concludes that in houses with warm-air heating systems a single helium analyzing cell in the return air-stream would provide a satisfactory indication of house infiltration rate.

Describes experimental studies of the natural ventilation of four similar houses with different ventilating systems. Describes houses and gives experimental procedure and results of measurements of air-change-rates using hydrogen as a tracer gas.Shows variation in air-change-rates are due mainly to changes in wind speed and that wind direction and temperature difference are secondary factors. Estimates rate of heat loss as a functionof wind speed. Discusses relationship between measured pressure differences and wind speed and direction.

Reports tests made on a mobile home to evaluate its thermal performance. Describes home, instrumentation and test procedure. Gives energy consumption as a function of indoor-outdoor temperature difference. Finds that oversized heating plant resulted in low seasonal operating efficiency. Air infiltration was measured using pressurization technique and SF6 as a tracer gas. The latter showed that operation of the heating plant induced higher air infiltration rates. Reports thermographic survey of interior surfaces which showed air paths formed by wrinkles in the surface insulation.