Damper Application and News

Edition 2

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Welcome to the second edition of Damper Application and News.  This newsletter is for the users and suppliers of dampers and equipment for flue and process gases. 

In this edition we are trying out a new format.  Click on the headlines below to take you to the full text.



First Edition Response

There were many new subscribers to the newsletter joining the over 800 already receiving it.  If you know of anyone that might benefit, please forward a copy of the newsletter to them.

Welcome Our First Sponsor – High Temp Bearings, Inc.

High Temp Bearings, Inc. specializes in providing solutions to high temperature bearing applications. Formed in 2001, it is a leading supplier of carbon sleeve bearings to the Power Industry.  Their success is based on a simple plan, providing quality products at a competitive price and backing it up with available inventory.

To compliment their carbon sleeve bearing product, High Temp Bearings, Inc. has a full line of mounted ball bearings, split housed tapered roller bearings, rod end bearings, shaft collars and other related products. Their bearing products accommodate shaft sizes from 1/2" to over 14".

Newly offered is their NT self aligning bearings.  Please see the new product highlight below for more information.

Visit their web site for more information at http://www.hightempbearings.com/.

New Product Highlight - NT Bearing Technology

Until now, damper companies and others, had to rely on self-aligning graphite sleeve bearings for their high temperature and/or low maintenance bearing needs.  There have been many cases where these bearings seized or froze in the field, preventing operation of the equipment.   The HTB Corporation did extensive case studies investigating the causes of damper shaft seizures and then developed a product engineered to address these issues, the NT bearing.

The heart of the NT bearing is a modified PTFE composite system that is designed to offer all of the well established, low friction, excellent corrosion resistance, and high temperature performance of PTFE but with greatly enhanced mechanical properties.   PTFE and its composites have been well established in critical applications ranging from high pressure gaskets to harsh chemical processing and handling.

The NT, self aligning sleeve bearing is a complete replacement for non-precision, intermittent and continuously operating systems utilizing graphite at continuous temperatures up to 500 F˚ and speeds less than 100 RPM's.  This is idea for louver, butterfly and guillotine dampers, as well as many other applications.

The patent pending NT bearing sleeve offers the following features:

  • Continuous operating temperature of 500 F˚ with intermittent service up to 630 F˚.

  • Enables the use of carbon steel shafting where stainless was required to prevent binding with graphite bushings.

  • Has extreme resistance to chemical and environmental attack and will not cause other materials to corrode.

  • Eliminates the risk of seizing due to contaminate build up in the shaft to bearing interface.

  • Has a very low coefficient of friction (0.06-0.360), and significantly reduces the force required to actuate a loaded shaft versus graphite.

  • Has been engineered to resist cold flow at elevated temperatures

  • Electrically non-conductive.

  • FDA approved material for direct food contact.

  • No change in installation or housings from traditional graphite sleeve bearings.

  • Maintenance free design.

  • Available in any standard bearing size and housing.

  • Cost effective replacement for graphite.

Housing configurations are pillow block, 2 bolt flange, and 4 bolt flange.  These accommodate shaft sizes from 1" to 3" as well as metric 25mm to 78mm.  Contact HTB for other sizes.

Visit the NT Bearing Technology web site for additional information including Chemical capabilities, Mechanical Properties, Thermal Properties and Case Study at http://www.getthecarbonout.com/.

Common Failures in Dampers

Reliable dampers are important to the operation of power and process systems.  There are many variables in damper and manufacture which ultimately determines the success or failure in a specific installation.  In order to have confidence in the proper selection of damper equipment, it is important to understand where problems have occurred and to see how damper manufacturers address these areas.  One of the most common reason for failure, is the use of dampers under-designed for the actual application they are being used for.  Clear definition of the operating conditions need to be provided in your request for quotes.

Louver Problems:

  • Linkage misadjusted or losses by vibration.

  • Lightweight link bars prone to buckling.

  • Bearing fouled with flyash causing binding. 

  • Bearing/Shaft thermo expansion binding. 

  • Leakage though poor packing glands.

  • Actuator undersized for actual service conditions.
  • Non-Repeatable limit switches, gear failures, burned-out motors.
  • Flyash build-up causing obstruction in seal areas.
  • Over-rotation of blades causing poor sealing.
  • Blade ends jamming against side frames.
  • Distortion and warping caused by heat or pressure.
  • Poor performance.

Guillotine Problems:

  • Jamming and unreliable operation from undersized actuator.

  • Failed chain, Buckled jackscrews, cracked bearings due to undersized drives.
  • Sprocket and bearing failure.
  • Gas leakage in ambient and system due to deteriorated seals.
  • Blade binding and jamming.
  • Particulate build-up preventing complete cycling.


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Everyone knows the old adage "you get what you pay for".  However, you certainly don't want to buy more than you need.  A good quality damper will last the life of the plant with minimum maintenance.  A few basic steps will insure your get the right damper:

Step 1 - Provide accurate operating and design conditions.  Indicate if it is a clean system or if it has flyash or other particulate in it.  Include all upset conditions.

Step 2 - Determine the level of performance needed: speed, frequency of operations and allowable leakage.  Higher performance costs more and is usually harder to maintain. 

Step 3 - Select equipment best suited for the application better.  For example, louvers for control and guillotines for isolation.

Your damper manufacturer can help you summarize criteria and develop a successful purchase and installation.

News Release and Articles Welcomed

If anyone has any ideas, news releases, or wish to contribute an article please send it to Damper Don

I would also like to recognize individuals who contribute to this industry and perhaps are in the background by giving them a spot light in this newsletter.  If you have a vendor or fellow employee you would like to see recognized, please send us an email.

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