July 2007 : FDA PowerGuard Guardian Out Performs the Competition

July 2007 : FDA PowerGuard Guardian Out Performs the Competition

As de-dusting regulations have tightened over the last several years, coal fired power generation stations, coal handling facilities and coal mining companies have turned to installing chemical dust suppressant sprays on their conveyor systems to reduce coal dust. While these spray systems are effective, the use of some of these products has been devastating to conveyor belt life.

Surprisingly, there are still several smaller belt manufacturers who promote their products as “unaffected” by dust suppressants, but the facts prove otherwise. For nearly four years Fenner Dunlop and our network of distributors have sought to educate end users about the negative effects these chemicals have on rubber compound conveyor belting, while developing new products to extend belt life when exposed to these leaching agents. Extensive lab testing as well as real world studies have proven that some de-dusting agents extract plasticizers from rubber compound covers. The results often lead to premature cover deterioration in the form of cover hardening, cracking, cover chunking and belt curl.

Fenner Dunlop’s PowerGuard Guardian cover compounds are specifically formulated to retard the negative effects of chemical dust suppressants. Guardian AR is designed for those applications requiring additional abrasive resistance. Both compounds are fire retardant. To further protect the end user’s conveyor belt investment and to guard against potential belt curl, both are offered with a minimum bottom cover thickness of 3/32″.

How effective are Fenner Dunlop’s Guardian compounds in actual applications? To find out, FDA and a representative from Bi-State Rubber, a Fenner Dunlop TCSD distributor based in Fenton, MO, visited a barge coal loading facility on the Illinois River utilizing Fenner Dunlop Guardian belt on one 60″ conveyor and a belt from a domestic belting manufacturer from the south on a twin 60″ conveyor. Each system is 410′ long (830′ of belt in each system) splitting 1300 TPH of 2″ x 0″ clean coal. Both systems convey approximately 550,000 tons per year. The facility has been using dust suppressing chemicals for about 5 years. Sprays are located at the tail and drive end of both systems. A mix ratio of 1.5% to 2% chemical to water is applied.

A Fenner Dunlop 3 ply 600 belt with fire retardant first generation Guardian covers was installed in January 2004 on the south side conveyor. In February, 2005, over a year later, a 3 ply fire retardant belt from this same domestic belting manufacturer was installed on the twin north side conveyor. Chemical dust suppressants have been sprayed on the coal conveyed on both systems since belt installation.

To measure the potential deterioration (hardening) of both belts, durometer readings were taken at equal spacing along 300′ of exposed belt in each conveyor. At each location, three readings were taken in the coal loading areas and 2 readings were made on the bottom cover. Conveyor belt covers from most domestic manufacturers average 65 durometer when new. Conveyor belt will often require replacement when their cover durometer readings reach into the low to mid-90s.

Sample Durometer Readings
Fenner Dunlop
Cover Guardian MSHA Other Domestic Belting Manufacturer
Top 72     74     71 83   86   84
Bottom 76    74 84    85
Top 72     75     70 85     85     83
Bottom 76    76 82    84
Top 72     75     73 80     80     85
Bottom 78    76 85    82
Top 75     72     73 81     82     84
Bottom 76    75 85    84
Ave. Durometer 74 83
Belt Age 35 Months 23 Months

The Fenner Dunlop Guardian belt is clearly out-performing the other brand. At the current rate of durometer creep, it’s safe to assume the other domestic belting manufacturer’s belt is dramatically affected by dust suppressants and will fail due to cover deterioration years before the Guardian belt, possibly within the next 12 to 18 months.

The maintenance manager at this facility indicated other problems with his other domestic belting manufacturer’s belt including belt slip at start up – he felt due to hardening covers. The belt was also experiencing ply separation with stringing along the edges.


This case study confirms FDA’s scientifically backed claim that a specifically formulated cover compound is required to guard against the devastating effects of de-dusting agents.

While this end user may have “saved” a few cents per foot on the initial investment for the other domestic belting manufacturer’s belt with generic covers, he actually wasted thousands of dollars on a product that will require replacement years before the Fenner Dunlop PowerGuard Guardian belt.


Originally posted on the Fenner Dunlop website. Written by: Jerry Lovitz – Territory Sales Manager for the Midwest and Southeastern USA

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