Leaks of compressed air and gases like nitrogen, carbon dioxide and refrigerants can waste significant amounts of energy, e.g., because compressors must run harder to maintain pre-set pressures. In addition, such leaks can pose broader negative impacts — on the overall plant, the environment and, quite possibly, the well-being of the personnel.
Air leaks can compromise the performance of control and pressure-reducing valves that play essential roles in processing and so can cause impacts far from the leaks. At some sites such as biotech facilities, compressed air may regulate ambient humidity and temperature in critical research and production areas; leaks could lead to environmental excursions that ruin months or years of work.
Other gases are quite a bit more expensive than compressed air. As a rule of thumb a nitrogen leak typically is ten times more costly than an air leak. So living with many nitrogen leaks will take a big bite out of your profits. For a volatile gas such as natural gas, identifying and repairing the leak becomes an urgent priority. The potential safety hazard far outweighs actual gas cost. Inert gases such as argon, helium and nitrogen aren’t toxic and don’t burn or explode. However, they can cause injury or death at high concentrations by displacing oxygen in the air. Leaks of carbon dioxide add to the environmental problem of “greenhouse gases” and so may pose regulatory issues in the future.
Clearly, performing leak audits on a regular basis makes sense.
A proper audit looks at all components of a compressed air or gas system. It should validate operation of critical components. It also should scan and leak-test non-critical components such as relief and solenoid valves, flange gaskets, filter/lubricator/regulators, and threaded, welded and quick-connect fittings and devices.
Compressed air systems should supply clean dry air — and this depends upon the condition of drain traps in the condensate system. A trap failing in the closed position causes condensate backup. Air fed to the system will contain water that can harm equipment. A failed-closed trap also can lead to problems from dirt and corrosion. A trap failing in the open position wastes large quantities of energy. Because most traps are piped into discharge manifolds and then to waste drains, it’s not generally visually apparent that they might have failed open.
Valves, solenoids and other sensitive equipment can plug or stick in an open position and eventually fail. Gaskets between banks of solenoids often begin to leak when water hasn’t been drained from the compressed air system. Sometimes oil carried by the air can cause O-ring or gasket failures. Air lines and other equipment outdoors subject to low temperatures can freeze, leading to cracks and permanent damage.
It’s crucial to find and correct leaks before a small problem becomes severe. In our business there’s an old truism: “Everything leaks, it is just a matter of when.”
Doing without a leak identification and repair program will add a hidden cost to production that can negatively impact your company’s competitiveness and profitability. Plus, as we’ve noted, leaks can pose safety and environmental issues.
A number of questions regularly arise about audits. So, let’s answer them right now:
Is an air/gas leak audit cost effective even in a smaller plant? Yes. Leak detection pays off for any size plant. Leaks can represent a proportionately more important impact on competitiveness in smaller plants, and a substantial actual cost in larger plants.
When we perform an audit in a large plant, we typically find losses of $5,000/day to $10,000/day or more from leakage. Once you get a handle on your leaks, it’s not unusual to be able to shut down one compressor.
How often should a leak audit be performed? Conduct one at least yearly; most plants can justify a semi-annual audit — losses uncovered typically pay for the cost of the audit many times over.