Maintenance and Operation Tips for Large Air Compressors
October 1, 2007
Lose air power on a drilling jobsite and work comes to a halt. Thankfully, air compressors are rugged machines that are well equipped to handle the rigorous environments where drilling operations often take place. In order to have continuous and productive drilling, routine maintenance and proper operation are necessary.
Maintaining the Compressor"I don’t think preventive maintenance is taken as seriously as it should be,” cautions David Stahlman, product marketing manager for large air compressors at Ingersoll Rand. “The cost of preventive maintenance will more than pay for itself in longer life of the air compressor.”
As with any piece of equipment, a routine maintenance schedule is a helpful tool to keep track of air compressor upkeep. A majority of the schedule calls for daily, weekly and monthly checks.
Daily checks are critical in making sure the air compressor is able to perform the work for that day, but Stahlman says too often contractors skip this part of maintenance. “Sometimes drilling contractors get so focused on drill productivity that they don’t take 10 minutes before starting work to make sure the compressor is in tip-top shape,” Stahlman observes.
An air compressor not in prime operating condition will consume more fuel. “True productivity means operating all equipment as efficiently as possible to maximize the number of feet drilled per day,” Stahlman says. “When an air compressor is properly maintained, it uses less fuel and is more efficient.”
Check the engine oil dipstick and the compressor oil sight glass on the separator tank daily. These checks make sure that oil is being kept within the proper levels. The engine and the compressor use the oil as cooling media and a lubrication source.
Other daily checks include monitoring the level of radiator coolant, making sure all gauges and lamps are in working order and checking the air cleaner service indicators and fuel/water separator drain. Most air compressors in drilling operations have only a small day-fuel tank and get fuel for normal operation from bulk tanks. The small tank should be kept full to avoid any unnecessary shutdowns or risk of getting air into the fuel lines. Drain any water that has collected from the fuel filters and walk around the machine to make sure there are no oil or fuel leaks. The air cleaner pre-cleaner dumps should be cleared if needed. Also, check the radiator cap to make sure it is secure. After all these daily checks are complete, the air compressor is ready to be started for the day.
Each week, there are a few extra checks that should be added to the daily inspection of the machine. Fan belts and alternator belts should be inspected to make sure they are properly set on the machine, and that they do not need to be replaced. Look at the battery connections to make sure they are in working order with a minimal amount of corrosion on the terminals. If the compressor is mounted on wheels, the tires should be examined to make sure they are properly inflated and treads are not worn.
Monthly checks include making sure tire lug nuts are tight, hoses are not frayed and the automatic shutdown system is working properly. The air cleaner system, the exterior of the compressor oil cooler and the engine radiator/oil cooler should be clean and in good working order.
At a minimum of 500 hours, the air filters should be replaced. However, if the air compressor is working in a dirty environment, the filters may need to be replaced before 500 hours and should be checked daily. “The air filters, which have a primary and secondary element, need to be free of as much dust as possible and replaced if they get clogged,” Stahlman stresses. “Keeping clean air going into the engine and the airend is the most critical thing in the maintenance schedule.”
Ingersoll Rand recommends changing the engine oil and filters every 500 hours of use. Other 500-hour maintenance points are inspection of the fasteners and guards, and replacement of the fuel/water filter element and compressor oil filters.
At 2,000 hours, the separator element needs to be replaced. “If the service air starts fogging or oil carries over out of the drill into the pit before 2,000 hours, then the element needs to be replaced,” says Stahlman. “Expensive oil is used in these air compressors, and money is going to be lost if the air/oil separator element is not working properly.”
“Maintaining an air compressor is similar to a car,” notes Stahlman. “It is important to stay ahead of trouble with preventive maintenance to make sure the compressor has a long life.”
Air Compressor OperationNot only is air compressor maintenance important, but correct operation is just as critical in keeping the machine running properly. The most important aspect of air compressor operation is where the machine is placed. Making sure the compressor receives clean, cool air and that hoses from the compressor are as short as possible are considerations in air compressor placement on the job.
“Because drilling environments are dusty, contractors have to watch how an air compressor is positioned next to the drill to prevent dirty air from going across the machine, clogging the heat exchangers and causing premature air intake filter restriction,” says Stahlman.
On most drilling jobsites, there are two compressors providing air. Just as important as keeping dirty air out of the compressors is positioning them so hot air is directed away from the jobsite. “Point the air compressors so they are not facing each other to prevent the air from one compressor from going into the other compressor,” Stahlman recommends. “The best way to position the air compressors is to have them side-by-side or V-shaped, so cool air goes into both; hot air and dust are directed away from the jobsite.”
“Keep hose lengths as short as possible,” advises Stahlman. “There are a couple of reasons for this. First, hoses should not be run over by equipment and people because they could become damaged. Secondly, a longer hose will have more pressure loss before the hose reaches the end of the drill string, which is where it needs to do its work. The air compressor also should have an aftercooler to extend hose life and manage water condensation.”
Service air temperatures of 200 degrees F to 250 degrees F are common in compressors that do not aftercool air in hot environments. Hoses that have hot air running through them will have a shorter life than hoses running air at cooler temperatures. Hot air running through hoses can cause water condensation inside the hose that could enter the down-hole hammer piston. This especially is true on colder days. If the ambient temperature is 40 degrees F and the air running through the hose is 210 degrees F, water condensation practically is assured. “If the air compressor has an aftercooler, the air is cooled before it gets to the hose, most water is extracted at the compressor, and less water creation occurs in the service air,” explains Stahlman. Aftercoolers increase the resale value because they make the air compressor a more versatile machine.
Hoses should be secured as a safety precaution. “Air is power. Use whip checks and make sure the hoses on the ground are protected and constrained so if one does blow, it doesn’t become a safety hazard,” says Stahlman.
Many contractors run an air compressor wide open during operation, even when the drill string is changed. Running an air compressor this way is not a problem, but Stahlman cautions contractors to make sure they have enough engine horsepower for the duty cycle. “Ingersoll Rand has excess engine horsepower built into our units for longer engine life because we know the duty cycle is fairly tough,” he says. “The horsepower rating on the engine is commonly 7 percent to 10 percent higher than what is consumed by the air, fan and the other subsystems. With this horsepower margin available, the engine is not working at its maximum capacity, which helps the user get a longer life out of the engine.”
Another operational tip Stahlman gives contractors is on service valve operation. He suggests that contractors open and close the valve slowly. Opening or closing it too quickly could lift a safety valve and cause the air compressor to lose oil, creating higher operating costs. “Just like in your home, slamming shut water faucets rattles the pipes. In an air compressor, the same thing can occur,” he explains. “Years of this type of activity will cause unnecessary wear and tear on the service air piping system.”
Jobsite TroubleshootingListening to an air compressor seems like an unusual thing to do when troubleshooting, but Stahlman says this is a good way to identify a problem with the bearings. “If the bearings start to go, the whine out of the airend will sound different.”
Not only should contractors listen to their air compressors to make sure they are working properly, but they should feel them as well. “Put a hand on a cool pipe that’s connected to the airend to feel the vibration,” says Stahlman. “If the vibration seems higher than normal, the airend may need to be rebuilt.”
Some foaming of the oil in the sight glass is normal, but excess foaming may be an indication that there may be a damaged tube, incorrect oil was added during maintenance or a problem with other internal compressor parts. Manufacturer-recommended compressor oil needs to be used to prevent foaming and oil carry-over. The oil is optimized for the compressor application with a proper amount of lubrication, additives and heat transfer characteristics.
By taking the time to care for an air compressor, and by setting it up and operating it correctly, drilling contractors can ensure the machine will provide them with many productive hours. Air compressors are durable, reliable products. But like any piece of construction equipment, they require preventive maintenance and proper operation to have a long life. Taking the preventive maintenance as far as possible will keep uptime at a maximum at the lowest total operating cost. In the end, that’s the goal.