Tuesday, September 3, 2013

Wet Evaporative Type Air Cooled Heat Exchangers

V-belt drives in wet evaporative type air cooled heat exchangers are sometimes converted to synchronous belt drives for more constant fan speed, reduced maintenance and to reduce energy consumption.  While these benefits are often realized from belt drive conversions in many industrial systems, this particular application can be especially challenging.

Wet evaporative air cooled heat exchangers are sometimes structurally compliant allowing drive center distances to flex while in operation.  This allows belts to loosen dynamically resulting in accelerated belt tooth and sprocket groove wear.  Moisture seems to accelerate the rate of wear further with Poly Chain GT Carbon belts.   The first Poly Chain GT Carbon belt may last up to 6 months or so, then 2 to 3 months for the second and then maybe a couple of weeks for the third.  Belt teeth typically wear to a sharp point resembling “shark fins”.  By this time the sprocket grooves are often worn severely as well.

Poly Chain GT Carbon drive system life can be extended up to 12 to 15 months in these adverse applications with nickel plating on the sprocket groove surfaces.  Nickel plating is best applied to fresh cleanly machined sprockets as opposed to sprockets that have been painted or coated previously and then stripped.  In addition, sprocket finish diameters for freshly machined sprockets are corrected to account for the added thickness of nickel plating.  This improves the belt meshing quality reducing component wear.  Our Made-To-Order Metals Group can assist with properly plated sprockets that will perform well.  Contact them at makemymetal@gates.com or at 800-709-6001.

A quick and easy test for structural compliance is to stop the drive system, safely lock it out and then pull or push the belt spans together.  If any shaft or structural movement can be detected, the structure is not adequately sound for synchronous belt drive systems. In these cases V-belt drive systems are probably the better choice.

For further information feel free to contact us at ptpasupport@gates.com or at 303-744-5800. 

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