Simple Procedure for Preparing Dilute Concentrations of Ethylene in Air or Oxygen in High Pressure Cylinders1

Abstract

Abstract Investigations employing gases other than air, e.g. mixtures of O2, CO2, N2, C2H4, etc., in dynamic systems usually employ gas mixtures prepared in high pressure cylinders or by elaborate metering devices and mixing chambers using component gases from high pressure sources (1, 2, 3). Both systems require analysis of the resultant mixture to confirm that the composition is within the desired range. Physiological investigations often require thousands of liters of unique and portable gas mixtures. Commercially prepared mixtures in high pressure cylinders are expensive and metering systems are cumbersome. We have devised a simple method for rapidly preparing (ca. 10 min) dilute (μl/liter) gas mixtures in portable laboratory-owned cylinders at pressures of ca. 140 kg/cm2 (2000 psi). This method can also be used to prepare gas mixtures in percentage composition at lower pressures, ca. 70 kg/cm2 (1000 psi). This method uses a pressure differential between 2 cylinders of compressed gas to inject a known quantity of another gas from a connecting manifold into the lower pressure cylinder.