Permeation Tubes – An Overview

The purpose of a gas standard is to establish accurate reference points for the verification of an analysis.

• Static mixtures in gas cylinders are often unreliable and inaccurate at the levels (ppm to ppb) that analytical technology now demands.
• In gas cylinders containing low level mixtures, the trace components often adsorb to, or react with, the cylinder walls causing the standard to be inaccurate and unreliable.
• Also, it may be impossible to get a matrix gas that is completely free of the trace component, thus making it impossible to get a true reference point with a cylinder mixture.

These problems are solved by using permeation tubes in lieu of gas cylinders.

 

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Types of KIN-TEK Trace Source™ Permeation Tubes

KIN-TEK manufacturers permeation tubes in two basic types – disposable and refillable – for over 500 chemicals.

Disposable Tubes

Disposable Permeation tubes are tubular devices about the size of a pencil with liquid component compound sealed inside. The component compound slowly permeates through the tubing wall creating a very small flow of component vapor. Disposable tubes have a finite operating life and are discarded at the end of that life. They are primarily used to make lower and medium concentration mixtures.

Refillable Tubes

Refillable Permeation tubes generally offer a broader range of concentration than disposable tubes. They are often recommended for long-term service and for applications requiring a broad range of calibration points.

Refillable tubes are used for higher concentration mixtures. They are also used for high pressure gas components (CH₄, C₂H₄, O₂, H₂, etc.) where the gas must be frequently replenished. KIN-TEK offers factory refill and recertification services; however, some tubes may be refilled by the customer (with appropriate safety measures in place).

High emission tubes in gas service are refilled in-situ, using controls in various models of KIN-TEK Gas Standards Generators.

 

To learn more, read “Permeation Tubes: A simple Path to Very Complex Gas Mixtures.” and “How Permeation Tubes Work.“