Chassis Components, Fire Department, Special Operations Hazmat

Maintaining CAFS

Issue 4 and Volume 12.

If the best advice for maintaining today’s CAF systems sounds a little simple, that’s because it is. It boils down to three words: run the system.

“You run the truck,” says Ray Frey, sales engineer with Waterous Arizona, Peoria, Ariz. “You theoretically run the pump. Run the system.”

Beyond that, CAF systems require the attention and maintenance common with any mechanical system. Filters and fluid levels need to be regularly checked; the system itself needs to be serviced periodically; and just like saws, generators, or power units, it’s a good idea to give regular once-overs before they are needed on a call.

“It’s no different than anything else,” Frey said. “It’s no different than their saws, their pressure relief valves. If you don’t take them out and check them, they don’t work.

Clarence Grady, foam system manager with Pierce Manufacturing, Appleton, Wis., agreed.

“The machinery does need to be run,” he said, “and whether you make foam with it or, particularly with the compressor, just develop a way of just moving the air, that’s the best thing you can do for it.”

For example, bringing the compressor up to temperature and running it for a short period – 5 to 10 minutes – burns the condensate out of the unit, Grady said. Turning on the foam proportioner also helps.

“The idea being that the concentrates can get waxy,” Grady said. “It’s not very heavy, but it starts to form. If you use the system periodically, [the wax] doesn’t have a chance to form if you can move it along and get some fresh stuff in there.”

He recommends running the system’s foam proportioner 30 to 60 seconds at least and at least once a week.

Maintenance Issues

“If you move it a little bit, then that (waxy buildup) either moves on down or doesn’t form, and you don’t see the build up and causing a plug up,” he said.

Other maintenance items to consider: try not to mix brands of foam. Some brands, particularly higher-end brands, are more compatible than others; check and, if needed, clean the unit’s “Y” strainers, which strain the foam as it moves along the system.

Particularly on a new truck, Grady said, check the strainers frequently, as tank shavings and other debris from the manufacturing process can find its way into the system. Additionally, strainers on systems used in wildland applications may require more attention because they can be impaired by leaves, pine needles, small rocks and other debris. Strainers can also get particularly dirty if drafting from a water supply.

“It depends on your department and the type of water they have in the community,” Frey said. “Departments, if they’ve got dirty water, they know it.”

Filters should also be regularly checked and changed, if needed. “It does no good for a department to invest $30,000 in a system and then not take care of it,” Frey said.

CAF systems typically include three types of filters: air, oil and the coalescer filter, which removes oil mist from the compressed air generated by the compressor. Keep an eye on filters early in the system’s use, then they can be changed as the unit is serviced. Coalescer filters, for example, can go two or three years between changes, but may need more frequent changes in areas of high humidity.

Departments will also need to pay attention to the system’s compressor. The compressor – typically a rotary-screw unit – is one of the CAF system’s main components. To drive out any condensate that may accumulate in the compressor, Grady recommends periodically starting the unit, bringing it up to temperature, then running it for a short period.

“The systems are made to run for thousands of hours,” Frey said. “Run it.

Grady said it’s good to routinely flow air through the compressor, although he cautioned against running daily as the tendency is not let it run long enough to burn out condensate. “That (condensate) is the biggest thing that gets to a rotary-screw type compressor,” he said.

It should go without saying that the system’s fluid levels be checked routinely as fluids are critical to any mechanical operating system. For CAFS, these generally include hydraulic fluids used in the compressors and other oils used to lubricate the system.

With the compressors, be sure to use an anti-foaming hydraulic oil, Grady said, cautioning that some brands indicate they are, but in reality they’re not.

Frey recommends paid firefighters make those checks daily. Volunteers should do it weekly. That includes checking fluid levels on the foam proportioner and compressor and on an auxiliary engine if one is used to power the compressor.

“Definitely make sure that when you change the oil in any of the systems, double-check, triple-check, whatever it takes, to make sure you have oil in that sump reservoir,” Frey said. “It will weld itself solid. Believe me, 30 to 60 seconds [more use] is all you’re going to get.”

Frey also warns about sump fires. Though rare, they can occur with an uncooled compressor lacking oil. “They’re extremely rare, but that can happen,” he said. “A sump fire due to lack of cooling is most catastrophic. The oil will heat to the point where it will ignite. The fire will literally go through the system.”

The bottom line, Frey and Grady said, is to use and maintain the system.

“Run the system,” Frey said. “I can’t emphasize that enough – to run the system. You’re not going to wear it out.”

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