I've been pondering hardware options to filter my onboard compressed air, I think before it goes into the tanks, since chronic high humidity and oily crap are obviously doing a number on my air-packs. My first thought was to use something from the ground-based world of compressed air, like maybe a 'motorguard' toilet-paper style filter. A local vendor suggested I look into DOT-approved standard heavy-truck air-filters, but Google fails me on that score. Anyone have experience with particular filtration devices?
As to the need or validity, maybe... don't rule out mechanical conditions here either. You should get a little something daily, but it shouldn't be that much with no filter.
As for Google failing you, don't look for a filter. What's approved and accepted and semi-standard in the trucking industry does exactly that, but it's called a "dryer". Truck shops, parts stores that deal with truck parts, and even Google are far more familiar with that term. Since it's a retrofit, pretty much anything will fit, and the sky is the limit. Check the install instructions online first. (All the major manufacturers have that). Some have unique install requirements that may or may not meet your needs and/or desires.
This may help. Bendix is a recommendation, but I'm not knocking ANY brand that's out there, they're all good and Bendix is not always the least expensive. When it counts "axles", it's looking for air brakes. You do not have that. Your hydraulic brake booster (airpack) accounts for less than one axle. Use one axle and no lift axles. If you tow trailers, count each axle for full air brakes, or one axle total if it's air over. For the air wipers if you're not afraid of driving in the rain, add another axle. These are not high demand systems at all, if you come up with a 2 it does not mean you are shortchanging yourself, you just can't burn up as much air as a four axle tractor with a four axle trailer, eight axles worth of airbag suspension eighteen brake cans needing to be filled each time you tough the brake pedal, maybe an air ride cab... Air ride anything dumps all the time, they are PIGS and need very large system capacities.
http://www.bendix.com/media/documents/products_1/airtreatment_1/BW2600a.pdf
Also, does the low-air-pressure warning sense directly from the tanks, or is it out on a line somewhere? (I want to be sure that as my filter plugs, I know about it before I lose brakes...)
--Dave
Yes, as does everything else on the truck. It actually does come from "out on a line somewhere", but if you were to rectify that it would still come from "out on another line somewhere", even if it's a line you put in. The tank is in fact no more than a fat section of line. I see exactly where you're going with this, and it's kind of a valid concern, but misguided at the same time. You can not sense the pressure everywhere at once. even if you had a gauge directly screwed into the tank, you can't sense the pressure at the end of the lines that supply the actuators (including the airpack), any of which can "plug" just as easily as any other, including your cab supply.
Lines can be restricted. With the gauge being at the far end of one of the easiest to become restricted, it will be the first place to show problems, and will show problems long before the tank pressure drops. If the tank pressure should drop, the shmutz stuck in a necked down fitting will be stuck from the tank side, so the pressure in the line will be an effective back flush, being in the opposite direction. Even if you could find a permenant blockage that couldn't be backflushed, that cab supply has the highest concentration of "normal leaks" that you'll ever find, demanding constant charging from the tank. If the flow stops, the pressure drops QUICK in that line. I don't think you could do better.
