Gastec Generating calibration gas with a diffusion tube

Generating calibration gas with a diffusion tube

A diffusion tube is a glass tube that consists of a liquid containing portion and a diffusing portion with a uniform inner diameter. A pure target liquid is put into the liquid container using a glass syringe. The liquid must have a vapour pressure of 5 to 400 mm Hg at 25 to 50ºC (77 to 122ºF) and be highly stable. If this tube is kept at a constant temperature, the liquid evaporates and diffuses at a constant rate.
*1 Although not a common application, gases of substances that are solid at normal temperatures can be generated using gas diffusion tubes. Please contact your licensed GASTEC representative for information regarding specific substances.

*2 This method cannot be applied to substances with extremely high or low vapour pressure or substances with decomposability, corrosiveness, hygroscopicity or polymerizability due to their diffusion rate not being constant.

Diffusion tube


Suitable for continuous generation of single component gases for calibration over sustained periods of time.

Diffusion tube for multiple components


Solvents such as thinner contain multiple components. Previous models permit the generation of single component gases for calibration purposes. However, a multiple component type diffusion tube enables the simultaneous generation of 4 types of gases for calibration. Employing this tube enhances analytical testing.