Clog Busters

Blinding sandstorms are slowing the U.S.-led advance through Iraq. Soldiers are afraid to stray from their vehicles for fear of getting lost; reduced visibility forces convoys to spend hours traveling just a few kilometers. But what effect has the swirling dirt had on the military machines themselves?

In the 1991 Persian Gulf War, tank operators had to stop to change their engine filters every 10 to 15 miles. It was a time-consuming and potentially risky operation, involving two vehicles and exposing the crew to hostile fire. This time around, that's one problem the Department of Defense hopes it has solved. Most of the M-1 tanks now moving through Iraq are equipped with a self-cleaning filter that can keep going for hundreds of miles without clogging.

The patented filters are made by Donaldson Company, Inc., a Minneapolis-based manufacturer of air cleaners for both military and civilian use. Tom Rice, Donaldson's market manager for defense products, spoke to NEWSWEEK's Arlene Getz about why the filter was designed and how it's holding up to its first conflict.

NEWSWEEK: How are the sandstorms likely to affect the operation of U.S. military vehicles in Iraq?

That dust in the air is more of a problem with visibility rather than with actual operation of the engine, because the engines are equipped with very good filters.

That's a change from the last gulf war, when tank engine filters had to be cleaned as often as every 10 miles.

That's correct--every 10 to 15 miles in the M-1 tanks. Those tanks were designed for conflict in Europe during the Soviet era, [but] all of that equipment ended up being used for the first time in a battle situation in Gulf I. It crystallized the army's thinking about upgrading filtration systems on many of the pieces of equipment that would be operating there. After the [last] gulf war a lot of things happened to improve filtration.

Such as?

In 1995 we started producing a pulse jet self-cleaning air cleaner for the M-1 tank that extends the range at least ten fold. Instead of 15 miles they could go many, many multiples of that because the filters are constantly being cleaned automatically while the vehicles are on the roll. The crew no longer has to get out of the tank and clean those filters.

So that improves the crew's safety?

Exactly. It extends the range of the tank, improves the mission capability of the tank and the crew, it no longer exposes the tank crew to hostile environments, it frees up the crew to do other important tasks, such as eat and rest. There are other obvious improvements too: better fuel mileage with the tank and much better engine performance because you no longer have to pull the filters out to clean them. Every time you do that, you run the risk of dirt or dust being ingested onto the clean side of the filter.

You say the tanks can now go hundreds of miles without having to change their filters. Is that still true in the sandstorm conditions we're seeing at the moment?

In the sandstorms the filters should be operating very well. We actually test those filters for worst-case conditions. The amount of dust that we feed to them is 20 times more severe than zero visibility conditions. The pulse jet systems in these M-1 tanks are designed to be following a lead vehicle that is generating dust and still perform without any problems.

How long did it used to take to change the filters manually?

It used to tie up two vehicles and it would probably take an hour or more. [The reason it tied up] another tank as well was because you're using compressed air from another tank to blow the dirt off the one you're trying to clean.

Do the tanks still have to stop when the filters need cleaning?

No, the tanks which are equipped with the Donaldson PJAC-pulse jet air cleaner-are cleaned automatically, there's no crew interface at all. So there's no crew involvement or decision making at all. It happens completely automatically. There's an electronic monitoring system that tells the system when to start cleaning or when to not clean.

Is this a patented design?

Yes, proprietary to Donaldson.

How much did filter changing slow things up during the last gulf war?

Every time [the crew] had a spare moment, they stopped to clean the filters because they never knew when they were going to have to go many miles forward. It changed how they went into combat during Gulf 1.

Has your system been used in combat before?

This is the first time, as far as I know.

Have you heard how it's holding up?

I have not. [But] I also haven't had any complaints.

What about extreme heat? A lot has been written about how the troops can withstand the high desert temperatures, but we haven't heard much about how military vehicles will stand up to heat.

That's a little bit beyond my area of expertise, but I can tell you that the air cleaner components are designed for the temperatures that are specified by government, both high temperatures and low temperatures.

What's the highest?

About 150 degrees [Fahrenheit].

Does the new system use new technology or just a smarter design?

Both. It's got ultra web nanofiber technology that's part of the filter media. The design uses a back pulse of compressed air to blow the dust off the filters, and that dirt is vacuumed out of the air cleaner and dumped overboard.

I guess you're watching TV pretty closely to see how your design is holding up.

I do watch, and fortunately to this point I haven't seen any photographs or footage of anyone stopping and cleaning their filters. In Gulf 1, there was a lot of news footage with filters actually strapped to the turret of the tank. I haven't seen that this time.