The Bureau of Mines has s u c c e s s f u l l y used s u l f u r h e x a f l u o r i d e (SF,) a s a t r a c e r gas t o measure mine a i r f lows under c o n d i t i o n s where c o n v e n t i o n a l methods have f a i l e d . SF, was employed e x p e r i m e n t a l l y t o measure a c c u r a t e l y r e c i r c u l a t i o n o f r e t u r n i n t o i n t a k e a i r caused by leakage thro...

We report on the experimental investigation of individual Cs atoms impinging on a dilute cloud of ultracold Rb atoms with variable density. We study the relaxation of the initial nonthermal state and detect the effect of single collisions which has so far eluded observation. We show that, after few collisions, the measured spatial distribution of the tracer atoms is correctly described by a Lan...

A push-pull ventilation system is effective for hazardous material exhaustion. Although a push-pull ventilation system has advantages over a local exhaust hood, some laborious adjustments are required. The pertinence of the adjustments is uncertain because it is difficult to evaluate the performance of a push-pull ventilation system quantitatively. In this study, a measurement of the capture ef...

[1] A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems ...

A transient experimental analysis of a three-phase descendent-cocurrent trickle-bed H2O/CH4Ar/γ-Al2O3 system was made using the stimulus-response technique, with the gas phase as a reference. Methane was used as a tracer and injected into the argon feed and the concentration vs time profiles were obtained at the entrance and exit of the bed, which were maintained at 298K and 1.013 10 Pa. A math...

For a better understanding and description of the mass transport phenomena in dense multiphase gas-solids systems such as fluidized bed reactors, detailed and quantitative experimental data on the concentration profiles is required, which demands advanced non-invasive concentration monitoring techniques with a high spatial and temporal resolution. A novel technique based on the selective detect...

To provide additional validation data for the multizone airflow and contaminant model, CONTAMW, experiments were performed in an occupied 3-story townhouse in Reston, VA. A tracer gas, sulfur hexaflouride (SF6), was manually injected within one room of the house and the concentration of SF6 was measured in each zone. This same process was then recreated in CONTAMW and the resulting predictions ...