Permeation Tubes
Why use Permeation Tubes?
The purpose of a calibration gas standard is to establish accurate reference points for the verification of an analysis. Static mixtures in gas cylinders are unreliable and inaccurate at the levels (ppm-ppb) that analytical technology now demands. In gas cylinders containing low level mixtures, the trace components adsorb onto the cylinder walls causing the standard to be inaccurate and unreliable. Also, if the analyte is polar or reactive, establishing a reliableF reference point using gas cylinder mixture is impossible. The Permeation Tube Method solves these problems.
We can also supply a range of Refillable Diffusion Tubes and these can be used for compounds with low vapour pressure and for custom applications.
Accuracy
Trace Source TM Permeation Tubes are reliable and accurate. They are certified gravimetrically and are traceable to N.I.S.T. Because the calibration standard delivered by the permeation tube method is used fresh, eliminating the adsorption problems and the problems caused by polar and highly reactive compounds that are inherent in gas systems.
Compliance
Many of our customers are increasingly concerned about compliance issues, OSHA, ISO 9000, GMP, and other industry requirements. Addressing these concern, KIN-TEK furnishes a certificate documenting traceability to N.I.S.T. with every certified Trace Source TM Permeation Tubes. Each perm tube is numbered and its emission rate is kept on file at KIN-TEK for up to 5 years. In addition to this KIN-TEK also offers an instrument Performance Validation Program.
Safety
Trace Source TM Permeation Tubes are very small compared to high pressure gas cylinders. Because they are so small (only about the size of a pencil), they contain only a fraction of the volume of toxic chemical contained in a gas cylinder. They are constructed of unbreakable material thus limiting the possibility of exposure. They eliminate the danger of handling high pressure cylinders, again because they are so small, are not breakable, have no valves and are not under very high pressure. Permeation tubes do not require special equipment to handle them or transport them.
Savings
One Trace Source TM Permeation Tube can replace as many as 10 gas cylinders. When used in a KIN-TEK Gas Standards Generator, one Trace Source TM Permeation Tube can deliver 10 or more different calibration concentrations. Plus, this can be done with accuracy traceable to N.I.S.T.
What are Trace SourceTM Permeation Tubes?
Trace SourceTM Permeation Tubes are small devices that have a permeable membrane and are filled with a pure chemical analyte. When held at a constant temperature, these devices emit a small stable flow of chemical vapor that is measured in nanograms or nanoliters per minute. Trace SourceTM Permeation Tubes are used in KIN-TEK Gas Standards Generators to create traceable calibration standards. Each certified permeation tube is serial numbered and the certification data is kept on file for 5 years.
How Do Trace SourceTM Permeation Tubes Work?
The emission rate of a permeation tube is dependent on four factors:
- physical characteristics of its permeable membrane,
- permeability of its chemical analyte through the membrane,
- temperature of the permeation tube and
- the partial pressure across its permeable membrane.
What types of Permeation tubes are available?
There are two basic categories of Trace SourceTM Permeation Tubes, Disposable Permeation Tubes and Refillable Tubes
Trace Source™ Disposable Permeation Tubes
Trace Source™ Disposable Permeation Tubes are polymer membranes about the size of a pencil containing the liquid phase of the component compound. These tubes are popular because they are so small and convenient to use. Plus, after all the compound has permeated out, the empty tube can be disposed of easily.
Trace Source™ Refillable Permeation Tubes
These tubes offer a broader concentration range than the Trace Source™ Disposable Permeation Tubes and are recommended for long-term use and special applications requiring a broad range of calibration points. Trace Source™ Refillable Permeation Tubes are available for chemicals not suitable for Disposable Permeation Tubes such as CO, CO2, NO2, methane, ethane, arsine & phosphine, etc.
Trace Source Refillable™ Gas Filled Permeation Tubes are refilled with the component gas periodically using the controls in a KIN-TEK Gas Standards Generator.
