THE FLOW OF HEAVY GASES THROUGH SMALL ORIFICES INCLUDING COMPARISON BETWEEN OXYGEN AND PERFLUOROPROPANE C3F8 AND PERFLUOROBUTANE C4F10 STUDIES ON THE FLOW RATES OF PEHFLUOROBUTANE AND PERFLUOROPROPANE OCTOFLUOROBUTANE

Journal/Book: Reprinted from The American Journal of the Medical Sciences Vol. 243 No. 1 January 1962. 1962;

Abstract: PRESBYTEHIAN HOSPITAL NEW YORK Summary. The flow of heavy gases through the restricted orifice of a standard regulator was similar to that expected by the formula of effusion or turbulent viscosity. Thus the relation of flow of oxygen to C3F8 and C4F10 was as 2.71 to 1 and 2.99 to 1. The theoretically derived flow rate would be 2.42 to 1 for C3F8 and 2.73 to 1 for C4F10. The discrepancy appeared to be due to temperature changes when the hydrocarbon compounds changed from a liquid to a gaseous state. The volume of air drawn through the carburetor of a nebulizer was 4.3 L. a minute per L. of oxygen as compared to 9.0 L. of air a minute per L. of C3F8.The volume of water nebulized at a constant flow of oxygen and octofluorobutane C3F8 increased in the proportion of 1 to 2.36 with the carburetor of the nebulizer closed and 1 to 3.13 with the carburetor open. These results manifest the greater drag effect an a water solution nebulized by a high-density gas such as C3F8. Under these circumstances a more dense aerosol would be produced. Provided that the velocity of flow of the gas from the lungs was not unduly low a physical propellant effect an mucus would be expected. The reduction in expiratory maximal breathing flow rates produced by heavy gas mixtures to some extent counteracts the physical advantage of increased density of the heavy gases. The use of a highdensity gas and a mechanically induced cough such as provided by the exsufflator would appear to induce a more pronounced expulsive effect an retained bronchial secretions than the use of either procedure by itself. ___MH

Zurück | Weiter