A permeation tube is a fluororesin tube that contains high-grade liquefied gas. When the tube is exposed to a certain temperature, liquefied gas penetrates the tube wall by osmosis in time-increments enabling a specific quantity of gas to be retained in the tube . Consequently, a carrier gas flowing at a constant speed (for calibration purposes) can be continuously generated by keeping the tube at a fixed temperature and infusing a constant quantity of dilution gas. This method is highly reliable because the concentration of the calibration gas is determined by calculating the decrease in weight of the permeation tube and the quantity of dilution gas. This dynamic method also enables highly reactive gases such as chlorine, hydrogen sulphide or ammonia to be generated. As shown in the table below, there are many different kinds of permeation tubes and they are widely used because they can provide a stable supply of calibration gas.
Gastec PD-1B-2 Permeater
A permeation tube is a fluororesin tube that contains high-grade liquefied gas
- Highly reliable because concentration levels are determined by calculating weight loss based on
- Many types (both organic and inorganic) of low-concentration calibration gases) can be generated
- Gas for calibration of all organic solvents (as long as they are stable in their liquid state or at normal temperatures) can be generated
- Gas for calibration can be generated continuously for longer periods of time
- Calibration gas can be easily generated in a wide range of concentrations
A diffusion tube is a glass tube that consists of a liquid containing portion and a diffusing portion with a uniform inner diametre. 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.
|Target gas to be generated||Permeation tube method: As a characteristic of the gas, the boiling point ranges between -60 and +30℃. In addition, the stable, high purity material used for the permeation tube enable the calibration gas to be generated.
Diffusion tube method: As characteristics of the liquid, the vapour pressure over the temperature range of 25-50℃ lies within the range of 5-400 mmHg. In addition, the stable, high purity material used for the permeation tube enables calibration gas to be generated.
|Accuracy of the generated gas||+/- 3%|
|Flow adjustment range||0.2-10L/min (Tapered tube 0.2-2L/min, 1-10L/min)|
|Temperature setting||5-step setting: 25, 30, 35, 40, 50ºC (When the difference between room temperature and the set temperature is 3ºC or less, cooling with city water or some other method is necessary.)|
|Temperature setting accuracy||+/- 0.15ºC|
|Dimensions||301(H) x 306(W) x 270(D)mm|
|Power supply, Max power consumption||AC100V 50/60Hz 180W|
|Dilute gas, Standard gas connection port||Tubes of O. D. 6 mm, and I. D. 4 mm|
Datasheet : Gastec PD-1B-2 Permeater