## What are permeation devices?

Dynacal permeation devices are small, inert capsules containing a pure chemical compound in a two phase equilibrium between its gas phase and its liquid or solid phase. At a constant temperature, the device emits the compound through its permeable portion at a constant rate.

### What is a permeation device used for?

It is used as a reference for the calibration of instruments in the field of gas chromatography, verifying the accuracy of analytical data generated from air pollution monitoring, industrial hygiene surveys, odor survey programs, and tracer studies, and in other instruments that measure gas concentrations.

#### What are permeation tubes?

A permeation tube is a sealed cylinder of a permeable material (such as PTFE) with an analyte of interest inside. The analyte will very slowly permeate through the walls of the tube, at a rate governed by temperature and tube geometry.

How permeation tubes work?

KIN-TEK Trace Source™ permeation tubes use a permeable membrane to dispense a small flow of chemical vapor. A very small but stable flow (nanograms-per-minute) of analyte vapor is emitted through the tube wall at constant temperature. The emission rate of the tube is determined by measuring the rate of weight loss.

What is the theory of permeation?

In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (such as a liquid, gas, or vapor) through a solid. It is directly related to the concentration gradient of the permeate, a material’s intrinsic permeability, and the materials’ mass diffusivity.

## How is permeation rate calculated?

Flux or permeation rate is the volume of liquid flowing through the membrane per unit area and per unit time and is generally expressed in terms of L m−2 h−1 and the permeability by L m−2 h−1 bar−1.

### What is the difference between diffusivity and permeability?

in a porous medium, the effective diffusivity is the molecular diffusivity divided by the tortuosity. The permeability does depend on the tortuosity, i.e. the effective length for a flow path for the same pressure drop, but also on many other geometric factors of the pore space such as effective cross section to flow.

#### How do you do permeation?

The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface.

What is permeation rate?

What is permeability in mass transfer?

## How do you stop permeation?

CO permeation can be reduced by:

1. Maintain tube temperature below 300F.
2. Increase wall thickness.
3. Burn-in tubing for 7 days.
4. Use alternative inert materials such as SilcoNert® 2000 lined stainless steel tubing.