What are the differences between online, inline, atline, and offline analyses?

Laser diffraction particle size analysis can be carried out in different processing locations, which can be classified as online, inline, atline, and offline measurements.

Online

The sample is extracted from the process line in a statistically representative way and introduced to the measurement zone via a sample inlet tube. The measurement conditions are similar to those of the process line. After the measurement, the sample can be drained as waste or introduced back to the process line. This method is primarily used for dense phase flow where there is a high concentration of particles in air or water.

Inline

The particle size analyzer is integrated into the process line, where the particle size analysis is implemented under the process conditions. After the measurement, the sample moves forward continuously along the flow. This was the original method for real-time particle size analysis and was only performed on processes or applications with a very low concentration of particles in air or water, called lean phase flow.

Atline

The sample is extracted from the process line and introduced manually or automatically to a laser diffraction particle size analyzer in its vicinity. The measurement is carried out by process engineers. The sample can be prepared again before the measurement. This can be an ideal method for applications where there are multiple process lines that all need to be monitored in sequence but without feedback control for optimization.

Offline

The sample is extracted from the process line and measured with a laser diffraction particle size analyzer in the laboratory a distance away from the process line. The sample can be prepared again before the measurement.

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