Air Monitors can supply and maintain your gas cylinder requirements, including regulators, fittings and tubing. We work with all of the leading gas manufacturers to deliver many specialist gas mixtures, some from our own stock at short notice. Call us for a quote on any gas, any mixture, any size.
Permeation tubes are made by sealing a liquid chemical in a tube made of fuoroplastic, nylon or silicon rubber depending on the permeant substance. It is essential that a liquid part is maintained in equilibrium with the gaseous part permeating through the plastic. The permeation rate is a function of temperature and to ensure stability of weight loss the temperature in the chamber containing the device must be better than 0.1 oC. The permeation rate remains constant until the liquid has been exhausted. In order to generate a concentration of gas in a calibration system the permeation chamber is purged with a low flow of pure gas. The diluent air flow can be varied to produce a series of different concentrations for e.g. linearity testing. The concentration of the gas standard generated in the system is calculated knowing the permeation rate of the tube and the sum of the purge and diluent gas flow. Many gases are available including NO2, SO2, Formaldehyde etc.
AMBIENT GAS CALIBRATORS
Gas calibration systems designed to dilute or generate gases as they are required for on demand automated calibration systems. These systems use bottled gas at higher concentrations and then dilute them to the required ppb concentrations with zero air. They also feature optional ozone generators, gas phase titration, photometers and permeation ovens.
See also gas mixing and dilution systems