Agitation – Reducing Agitation Stroke Requirement

The preceding blog described the benefit of part agitation in a cleaning process.  But, it is not always possible to provide adequate part agitation with a simple agitation of the part parallel to its central axis.  With a little creativity, it is possible to provide effective agitation of even very long parts.  In fact, there may be a surprising benefit of changing the orientation of a part to reduce the stroke required for its agitation.

Using a tube open on both ends for an example as we did in the previous blog, it is clear that to provide sufficient agitation stroke parallel to the axis of the part to both completely immerse it in and completely remove it from the cleaning liquid would require a tank depth sufficiently in excess of the length of the tube to allow for the agitation mechanism.  But, what if you have a tube that is 30 feet long?  Very few equipment manufactures would consider making a tank 30 feet deep, not to mention that to accommodate the agitation would require a 60+ foot high ceiling in the building housing the equipment.  The simple solution (which sounds like a “no-brain-er” but is often overlooked as an alternative) is to position the part on an angle as shown below.

Illustration of the effect of re-orienting a part on stroke length requirement.

By changing the orientation of a part, the agitation stroke amplitude required to completely fill and drain the part can be significantly reduced.

Positioning a part on an angle reduces the agitation stroke required to completely fill and drain the part significantly.  If I were a mathematician I would go through all the trigonometry to figure out what the reduction would be for a particular angle – but a mathematician I am not!  Suffice to say re-orienting the part for cleaning may provide a voila moment.

The following video illustrates the effect of placing a tube on an angle for cleaning.

Now for the surprise.  When the part is placed on an angle for agitation the speed of flow through the part as it is agitated is increased.  As an example, if a tube is agitated parallel to its axis with a 2″ per second stroke the speed of motion of the liquid within the tube is 2″ per second.  If, however, the same tube is placed at a 45 degree angle and the vertical agitation is at a speed of 2″ per second the speed of flow through the tube as it fills and empties is  2.828″ per second (OK, so I do know a little trigonometry – but don’t tell anybody).  An even more shallow angle will increase the rate of flow even more.  Faster flow can, in fact, enhance cleaning!  There may, therefore, be an added benefit to re-orienting a part for agitation.

There are a lot of things to think about when it comes to agitation.  So far, we haven’t talked about the speed of agitation but that is another significant variable that often isn’t considered.  Agitating a part rapidly by hand in a laboratory test may produce results that a slower agitation provided by a cleaning machine can’t equal.  Agitation speed is a topic for another blog.

–  FJF  –

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