The 10 Most Common Leak Spots in your Compressed Air System

The use of compressed air to power production processes is common across most manufacturing sectors. Production relies heavily upon this “fourth utility” to power their processes. Yet the fact remains that compressed air remains the most misunderstood and abused source of power in manufacturing today.

Compressed air system leaks are our biggest challenge for optimization. They are a wasteful way to add unnecessary demand to these maxed out systems. Operations demand a consistent supply of pressure and capacity in their compressed air systems. They need it; they want it; and when their compressed air systems are no longer capable of delivering, they scream.

So, if you find yourself tasked with troubleshooting your compressed air system for leaks, begin your search with these twelve common problem areas:

Check out our list of the top 10 most likely places to find leaks.

  1. Main Supply Line and Branch Connections

    Main supply lines typically come in two material composites; plastic and metal.

    Plastic pipes are an economical choice for many reasons. Plastic is easy to work with. It is lightweight, easy to cut, and easy to connect. Plastic does not corrode which means there is no worry about bits of rust getting into the compressed air system and fouling things up. Their smooth inner surface provides turbulent free laminar flow which adds efficiency and balance to the overall system.

    Where PVC piping is used, expect some leaks to develop. PVC is not an ideal material as it can’t withstand the high pressure demands of a compressed air supply line. Moreover, it becomes brittle and prone to cracking over time.

    Air leak inspections should focus on connection points and any bends in the pipe. Also check around suspension hangers as these are areas of strain which, when combined with vibration will be the first area where cracking will appear.

    Metal pipes are found in higher budget compressed air systems where the rugged look and feel of steel is preferred over the cheapness of plastic. However durable, steel pipes present their own challenges.

    Steel is heavier than plastic so stronger anchoring and suspension is required. Most steel pipes are uncoated which leaves them susceptible to corrosion; even if you use a good dryer system to eliminate moisture. Rusty pipes can cause damage to pneumatic equipment and contribute to compressed air system leaks.

    It takes longer to install steel supply lines. Pipes must be cut and welded, and more manpower is required to lift them into place. Threaded connectors, even when carefully installed, will eventually leak.

    Air leak inspections should focus on branch connections, 90-degree elbows, as well as any welded joints.

  2. Quick Coupler

    The quick connect/disconnect coupler is a common component used for branching in to compressed air system distribution lines. They are fast and easy means of connecting pneumatic lines and tools. They feature an automatic internal shut-off valve which allows lines to be connected without the need for separate ball valves.

    Quick couplers are primary sources of compressed air system leaks. The cause of failure can be a damaged O-ring, poor workmanship during installation, or misuse by operators. Focus your attention on these couplers when inspecting your compressed air system. They are easily replaced on the fl

  3. Filters

    Compressor manufacturers recommend using filtration at various points throughout the compressed air system to remove contaminants like pipe scale, corrosion, oil, and moisture.

    Filter bodies consist of both an air inlet and outlet port. These are prone to corrosion as well as thread damage when hoses or pipes are connected in a careless manner. This is the first area to inspect for leaks.

    A spinning baffle or coalescing element remove moisture from the air which settles at the bottom and can be emptied by simply opening and closing the drain port. It is common to detect the ultrasonic hiss of an air leak from the drain valve.

  4. Pneumatic Cylinders

    Pneumatic cylinders are utilized in many automated processes as well as on packaging and conveying lines to direct the flow of product through your facility. They are viewed as a low-cost solution and are easily exchanged when they reach end of life. However, they are subjected to constant movement as well as vibrations and eventually they will wear out.

    The first place to search for leaks is where the ram shaft exits the cylinder body. The rod seal continuously wears against the shaft and eventually fails. An ultrasound detector easily spots these external leaks from safe distances. Since cylinders are used to actuate machinery always use caution and follow safety procedures when performing inspections. If necessary, request a lockout during a shutdown to more closely inspect a suspected leaker.

  5. Dryer Assembly

    Water vapour in your compressed air system is a by-product of the compression process. As air is compressed its temperature rises which creates moisture which is released as the air cools during distribution through the plant. Dryer assemblies are used to remove moisture from compressed air systems which could otherwise foul pneumatic tools and corrode steel lines and tanks.

    Regardless of the type of dryer assembly used, they are all prone to leaks and should be a top priority for ultrasound inspections.

  6. Pressure Regulators

    Not all pneumatic tools are designed to operate at high distribution pressure levels. For this reason, regulators are used to control the pressures delivered to ancillary equipment. An internal diaphragm keeps compressed air from leaking out of the regulator.

    Because pressure levels are always changing, the diaphragm is forced to constantly flex. Contaminants like oil, dirt, rust, and moisture cause its rubbery consistency to become rigid. This combined onslaught eventually cracks the diaphragm allowing the regulator to leak expensive compressed air.

  7. Rubber Pipes

    Rubber pipes, air lines, and hoses are the most common method for branching into distribution lines within compressed air systems. It is typical to see these hoses dragged across the shop floor, driven over by lift trucks, pinched, slit, cracked, and otherwise abused. When not in use they should be stored on spring retained hose reels.

    No matter how or where they are in your facility, rubber air lines and hoses must be at the top of the list for leak surveyors.

  8. Lubricator Assemblies

    Pneumatic tools require lubrication in small doses. Lubricator assemblies send oil into the compressed air line in small atomized bursts. This component benefits pneumatic cylinders, valves, and other end use tools.

  9. Isolation Valves

    Isolation valves are usually installed downstream of the filter/regulator/lubricator (FLR) assemblies. These simple valves allow operators to control the flow of compressed air to pneumatic tools and ancillary equipment. They are a critical safety component in any compressed air powered process.

    Leak inspections should focus on the valve seat handle mechanism where the packing wears from continuous use. Often these leaks can be repaired by simple tightening with a wrench.

    Thread leaks from poor installation techniques are also common.

  10. Automatic Drain Traps

    Moisture is a common problem in all compressed air systems. Many mechanical systems are utilized to remove moisture and condensate to prevent corrosion, fouling, and extend useful life.

    Receivers, separators, filters, and regulators all require moisture removal. Automatic drain valves are either timer operated or actuate when the water column reaches a set height and releases a ball from its seat to allow water to flow. Once the water level drops, the ball re-seats to stop the flow of air.

    Common leak points are inlet/outlet lines and drain valves.


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