Permeation Tubes for Light Hydrocarbons

The Kin-Tek (USA) Trace Source 57 Series refillable permeation tubes extend the range of analyte compounds to include light hydrocarbons and other gases with vapour pressures too high for conventional permeation tubes. The 57 Series tubes are used in the Kin-Tek FlexStream calibration gas generator to produce ppm and ppb mixtures directly from pure gases.

Typically permeation tubes contain a liquefied analyte under its vapour pressure at the operating temperature of the permeation tube. This limits the range of compounds available in permeation tubes. 57 Series tubes use only the gas phase of the compound. Controlling the pressure in the tube allows high vapour pressure compounds such as methane, ethane, or ethylene to be dispensed by permeation. Emission rate is proportional to the compound pressure in the tube. For very low emission rates the compound can be sealed in the tube. For higher emission rates tubes should be used with the FlexStream GF Module to allow for compound pressure control and periodic purge and refill.

Mixtures can also be diluted if the tube is certified for each gas in the mixture. Single step dilution ratios of 1000:1 to over 50,000,000:1 can be attained allowing ppb mixtures to be made directly from the pure analyte compound.