Radial seal technology gains in popularity.

A diesel engine needs two things to operate efficiently -- clean fuel and clean air. When trucks equipped with Donaldson Corp.'s RadialSeal air filters first rolled into maintenance facilities two and one-half years ago, it's not unlikely that a cheer went up from the shop floor. Not just because the new design proved to be totally leak free (that level of performance had been expected), but because radial sealing made heavy-duty air-intake systems much easier to service.

Before the arrival of radial seals, the heavy-duty industry worked almost exclusively with axial seal filters. These require more time to install and remove, and there's a greater chance of dirt getting into the engines while they're being serviced. By contrast, the radial seal element can be slipped into a plastic housing, and with minimal pressure the technician can actuate the sealing element.

As the radial seal's popularity swelled, most major filter suppliers offered their own versions.

For instance, Fleetguard's Magnum RS is made with an extra sturdy removal/installation handle. Manufactured with galvanized hot-dip steel, it can withstand a minimum 250-lb. pull. The cartridge's open end now contains a durable polyurethane seal.

Although the configuration of the radial seal has remained largely unchanged since initial introduction, improvements have been made in media material and construction.

A&L Systems distributes Farr's Enginaire precleaners, which are designed to remove 99% of contaminants from the air before it (air or contaminants) reaches the engine, thereby prolonging engine life and reducing maintenance costs. Designed as "problem solvers" and aimed at the segment of the market seeking superior performance, Farr manufactures precleaners suited for almost all types of engine-powered equipment, including on- and-off-road truck use.

Farr also makes the Eco Series, which are said to provide an air cleaning efficiency of 99.9%, as determined by Society of Automotive Engineers (SAE) J726 standard. The Eco units are self-contained and fully disposable and feature a water-resistant, mechanically pleated paper element that provides low duct velocity (4,000-5,000 fpm). This eliminates the problem of pleat bunching and distortion, which can shorten element life.

ACDelco uses Delphi's pleated paper media with oil-wetted resin. This light wetting enables the element to trap 50% more particles than dry filters, the company claims. According to ACDelco, their design traps "at least 99% of all air contaminants of 10 microns in size or larger."

Advanced Maintenance Technologies distributes Racor's Nu-Tech filter, which is said to trap up to eight times more contaminants than the single-stage pleated paper filters. The Nu-Tech filter is water repellent, eliminates soot and salt penetration, and controls related problems such as icing and corrosion. This is accomplished through use of a three-dimensional, triple-stage media treated with a specially formulated viscous-impingement chemical compound.

After testing a radial seal product for use on a wide variety of truck engines, Baldwin Filters announced that the new filter removes 99.94% of contaminants and provides a contaminant-holding capacity of 2,458 grams. Its seal has been laboratory tested to maintain its integrity at extreme temperatures of -20 deg.F to +250 deg.F.

Hastings Filters has recently expanded its line of heavy-duty filters for trucks and off-road equipment. To help maintain pleat spacing and stability, Hastings uses a locked pleat construction and spiral glue binding. Added filtration surface is provided through a special plastisol binder that does not extend into the path of the air flow. The new filters also feature flexible outer edges that allow easy insertion and removal in tight housings. The end cap is reinforced to prevent constant flexing and potential failure during changes in intake pressure.

The Wix Filtration Products Div. of Dana Corp. has developed "skip-a-pleat," a new design that helps the pleats in the filter media stay open to catch a maximum amount of contaminant before the filter reaches an unacceptably high level of restriction. Wix has also developed a new metal end-cap with specially formulated gasket glue to increase adhesion.

The company offers a filter monitor to measure the amount of restriction to the air flow through the air filter housing assembly, which will help determine when to change filters. Wix warns that when air filter restriction gets too high, it can lead to reduced power and increased fuel consumption. The monitor, which "locks up" at the highest restriction measure that occurs during engine operation, shows at a glance when filter service is required. This helps avoid the needless replacement that sometimes happens when a filter looks dirty, but is still working efficiently.