Maintenance cost, the industry standard is $0.35 cents per gasoline gallon equivalent. The easiest way to think about this is in terms of “fully funded depreciation.” On larger systems the blow-down tanks need to be drained and all oil levels checked every day, plus observations for unusual noise/vibration, visual checks for oil leaks and gas leaks. Some high-end large stations have gas leak detection equipment. Every 50 hours of operation maintenance includes topping off the oil tanks, stage pressure readings and completion of the maintenance logs. Every 200 hours you have oil changes. At 500 hours you have coalescing filter replacements, Compressor Valve checks, intercooler tubing checks and visual inspection of all components. Between 3000 – 8000 hours of operation you can expect to replace the valves, piston rings, crankshaft bearings, etc. All of the items listed are common among all compressor manufacturers but they do vary from model to model.
Any time you have metal-on-metal moving parts, equipment is going to wear out. The industry standard of $0.35 per gge should also cover the owner if there is a catastrophic failure of a major component that needs to be replaced. We bank the 35 cents in separate accounts for each compressor to cover everything from regular maintenance to full replacement. A person would think that those accounts would eventually build up to the point that a facility could eventually stop that portion of the fueling accounting, but the industry knows that the longer a system runs the more maintenance and repairs will be needed. I do not want you to think that CNG fueling stations are always breaking, they don’t. But this is entirely depending on the quality of the routine maintenance. We have systems that have been in place over 25 years and are still running just fine. We also have clients that do “nothing” and wait for the equipment to fail. Experience has taught us that this business model results in very high repair bills and a lot of stress on the manager of the motor pool when they cannot fill up their fleet vehicles because they’re down for days waiting on parts.