COVER STORY
ELIMINATING WATER
contamination In the dog days of summer, people often say, “It’s not the heat, it’s the humidity.” This is true – on a hot day, it’s often the humidity that makes us suffer most. Unfortunately, pneumatic machinery also suffers from an increased likelihood of water in its air lines.
How water forms in air lines One of the most prominent triggers for excess water in pneumatic air lines is an increase in temperature. When temperatures rise, water evaporates and increases humidity, meaning there is a higher amount of water particles in the air. Since pneumatics rely on this air, it’s not surprising that systems release a significant amount of water during the hotter months. In fact, a 25-horsepower compressor can release more than 18 gallons of water in one day during the summer. Another trigger for excess water in an air line is fluctuation in air temperature. If the air temperature drops lower than its dew point (the atmospheric temperature at which water droplets can condense), water vapor condenses to form water. At this point, the relative humidity has essentially reached 100%. A typical example of this phenomenon is when, on a hot day, droplets form on a glass with cold drink. The same thing happens in pneumatic systems. Temperature fluctuations in day-to-day operations, or throughout the system itself, could potentially cause a similar “dew” to form within the system. If the air is carrying water vapor and goes from hot to cold within the line, vapor will condense to form water that will likely accumulate throughout the system. 12
NOVEMBER 2020
IN AIR SYSTEMS
By Michael Schapoehler, Product Technology Manager, Airline Hydraulics Corp.
It is a natural occurrence for water to be present in the air and fluctuate between its gas and liquid states. So why is it so harmful to pneumatic processes and machinery?
Bacterial growth. This moisture can also lead to the growth of bacteria and microorganisms in pipes and components. Some of these organisms can survive and multiply in higher temperature ranges, such as 45°C to 90°C (113°F to 194°F); others need lower temperatures, ranging from 25°C to 40°C (77°F to 104°F). However, the one thing they all need is moisture. Pneumatic lines can become breeding grounds for bacteria and mold that can gunk up components and cause health and safety concerns. Pipe scale and rust. Moisture also wreaks havoc on piping through the formation of pipe scale and rust. This buildup accumulates to decrease the pipe’s interior surface area, which increases the pressure loss as air passes through and reduces the system’s overall performance. Over time, the pipe scale and rust detach from the piping, traveling through the pneumatic system and causing further issues. Pneumatic components are intricate, precise, and relied on to make a pneumatic system run properly. When components become clogged with debris, a machine cannot operate at full capacity and may even
Why water must be removed Even a small amount of water within a pneumatic air line can result in big issues. Here are a few problems that occur when excess moisture goes unchecked. Loss of component lubrication. Pneumatic components are prelubricated at the factory. Water in a compressed air system compromises this lubrication and even has the potential to wash it away entirely. Unfortunately, many components rely on this lubrication to function correctly; without it, they are subject to premature wear and failure. It does not take much water to wash away the lubrication from smaller valves typically found in pneumatic systems. Within these components, rubber seals are prone to swelling, stiffening, and deterioration when subject to moisture.
A tiny valve can quickly become clogged with corrosion, rust, or pipe scale from water in an air line, leaving small components vulnerable to premature failure.
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