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Measurement zone

The flow cell houses the measurement zone of the analyzer. A laser beam shines across the powder stream as it moves through the cell area. The laser shines through glass (or sapphire, for abrasive powder applications) windows with special anti-reflective coatings protect the instrument electronics from the powder stream. There are two windows, one for the transmitter (which houses the laser) and one for the receiver (which houses the photodetectors). An air purge on each window protects them from powder fouling. The window purge is very effective, minimizing the amount of routine maintenance required for the analyzer - in general, typical installations can run for from a week to a month without manual cleaning of the windows.

Malvern can provide two types of flow cell, to be used either in-line or as part of the jetstream eductor process interface:

  • In-line flow cell: there are two variants, 25mm and 50mm. They are useful in smaller pilot/production facilities e.g. small milling facilities. They have a standard build and can be supplied "off-the-shelf"
  • Flange unit: for larger process pipe diameters (i.e.> 50mm), a custom made "flange" unit can be designed and built. These units come with a facility to adjust the optical path-length of the laser beam, so as to minimize the risk of measurement saturation errors.

A special pharmaceutical option is available, where the flow cell is manufactured from solid metal block so as to prevent potential bug traps forming.