Common Compressed Air Service Questions, Answered
We’ve all been there…the heart of your air system and possibly your facility – the air compressor – is acting strange and you aren’t sure why. Possibly it’s losing pressure or perhaps you’ve noticed that it’s running more often than usual. Unexpected breakdowns and issues can wreak havoc on operations and production, so it’s best not to ignore the telltale signs of trouble. Instead, determining the root cause of common air compressor issues before they escalate into a catastrophic failure can help avoid costly repairs and lost production time. To that end, below we troubleshoot potential causes of some common air compressor service issues so you can find the problem, fix it and get back to producing product.
Answer: The loss of air pressure between the compressor and the point of use may be a common occurrence in air systems, but it is one you want to avoid because unstable pressure means the compressor is working harder to push the air through the system, which uses more electricity. Pressure drops can also lead to situations where tools and equipment are not receiving enough air to power their operation, creating production inefficiencies.
So, if your compressed air system pressure has decreased, an inspection of the compressor is warranted. It could be a plugged inlet filter or separator element, malfunctioning inlet valve or a control problem on the compressor itself, all of which require service.
Another cause may be related to the addition of new production equipment. If this is the case, you may be exceeding the capabilities of the compressor and it simply can’t keep up with peak demand any longer. In this situation, further investigation and, possibly, an air system study may be needed to confirm and determine the correct course of action to remedy the situation.
Additionally, anything that causes a leak or restriction between the air compressor and the point of use could be the cause of pressure drop and the root cause can usually be found in either the air distribution system or related auxiliary equipment.
The air distribution system includes piping, tubes and hoses through which the compressed air travels to the point-of-use equipment it powers. If there is an obstruction or leak within the air distribution system, it can result in pressure drop. Piping that is undersized or poorly laid out will also result in loss of pressure throughout the system. Inspection of the distribution system may reveal a blockage caused by dirt, corrosion or rust particles, which should be remedied and the root cause of the blockage (such as changing a filter that was overloaded with dirt and dust) should be addressed. Leak detection tools will help maintenance technicians identify and repair leaks in the distribution system, which, once repaired, will restore pressure if leakage was indeed the issue.
If neither of these issues is causing the pressure drop, examine the design of the distribution system. Undersized or complex routing of pipes, hoses or tubing may be the culprit. Undersized fittings and quick-disconnect couplers on hose drops used to supply compressed air to machines are also common causes of pressure drop at the point of use. Identifying and correcting distribution system restrictions and leaks will help restore efficient operation and reduce the workload on the compressor.
Finally, compressed air treatment equipment such as dryers, filters and drains may also be potential sources of pressure drop. As inline filters become loaded with the particulate and oils they are meant to remove from the system, pressure drop will increase. Regularly inspecting and changing filter elements will help alleviate any pressure drop associated with dirty filters. Low pressure drop mist eliminator type filters with a 10-year element life expectancy are also a good option to consider. Air dryers must be sized properly and in accordance with the CFM, pressure and temperature of the air system. Automatic drains should also be inspected regularly as a drain that is stuck open or an electronic timer drain that is opening more often than necessary will cause pressure loss. In some cases, energy-efficient, zero-air loss automatic drains should be considered. If you determine that pressure drop is occurring within the air treatment equipment, properly sized replacements will also help reduce the workload on the compressor and restore efficient operation.
Answer: Air compressors work hard to pressurize and move air, but they can generate a lot of heat in the process, thus the need for lubrication, which often also serves as a coolant for the compressor. If the heat is not removed due to a plugged cooler, incorrect lubrication or contaminated lubricant, compressor gears, seals and bearings will fail prematurely. Lubricants can become contaminated due to clogged filters, intake air contamination or high moisture content in the system. For this reason, periodic testing of the oil for contamination is a must if you want to prevent unplanned downtime. It’s also a warranty requirement for most compressor manufacturers.
When you run an oil analysis on your air compressor, you are looking for wear metals, contaminants and degradation that may be present in your lubricant. This provides valuable information regarding the wear rate and overall condition of the unit and helps identify potential problems at an early stage and plan condition-based maintenance to help avoid clogged coolers and/or premature air-end failure, which can lead to unscheduled downtime.
In addition, common oil analysis tests include viscosity, since variations in viscosity usually indicate potential problems. Water contamination such as moisture in the system leads to corrosion and wear; IR and TAN tests allow you to see if the oil is being degraded due to acid formation from moisture or heat; particulate count and classification point out if there are external contaminants in the system; and elemental analysis can determine where particulates are coming from and whether the oil’s additives have been depleted.
A professional oil analysis report will include a list of all the metals, contaminants and additives found in the sample along with information about the level of risk for each contaminant or issue and will typically categorize findings into “normal,” “needs monitoring,” “abnormal” and “critical.” This information can then be used to correct high-priority issues before catastrophic failure and add less pressing problems into planned maintenance schedules.
Answer: As described earlier in the pressure drop discussion, if the compressor is running more often than usual, an inspection of the compressor may be necessary, plant demand may have increased due to additional equipment that was recently added, there may be a problem with controls or a restriction or new leaks may have developed. If the compressor will not shut off when it should, there are many possible causes, including a faulty pressure sensor or switch, which could lead to relief valve blow off; a dirty inlet filter; malfunctioning inlet valve or controls; compressor wear and tear; or increased plant demand.
Troubleshooting these and other issues when you first notice them is far wiser than letting them go. If you require further troubleshooting assistance or have other maintenance-related inquiries, please reach out to a representative at JHFOSTER.