PLASTIC ENCLOSURE

550 255 42A PLASTIC ENCLOSURE is usually found carrying low-pressure air or water on the rig. Think pilot air lines for controls, maybe a water spray line for dust suppression at the bit, or even a simple drain line for condensation. It's not for your main hydraulic circuits, obviously; it's designed for those lighter duties where you need flexibility and a bit of chemical resistance without the heavy-duty pressure rating. It just moves the necessary fluids from point A to point B to keep things like your air-over-hydraulic valves or water injection working right.

When this hose starts to go bad, you’ll usually notice a few things. If it's an air line, you might get sluggish controls, maybe a delay in a cylinder actuating, or even a constant hiss if it’s chafed through somewhere. For water, you'll just see drips, or a puddle forming under the rig, which can sometimes trigger a low-level alarm if it's a critical cooling or dust suppression line. The plastic can get brittle over time with heat and vibration, leading to cracks, or it can get pinched and restrict flow, causing all sorts of weird behavior downstream.

Replacing one of these isn't rocket science, but you gotta make sure you route it properly. Don't just yank the old one out and shove the new one in without checking for pinch points or areas where it might rub against a frame member or another hose. That's usually what kills them prematurely. Also, when you're putting on the fittings, don't overtighten the plastic compression fittings; they'll crack, and you’ll be back doing the job again next week. Just snug them up until they seal.