1. Choosing line sizes that are too small for the desired air flow. This includes the interconnecting piping from compressor discharge to the header and the distribution lines conveying air to production areas and within the equipment found there. Undersized piping restricts the flow and reduces the discharge pressure, thereby robbing the user of expensive compressed air power. Small piping exacerbates poor piping practices by increasing velocity and turbulence-induced back pressure.
2. Undersizing the compressor. This common practice leads to higher maintenance costs as well as premature failure. Sizing the entire system with an understanding of expected air flow demand is critical.
3. Not managing air demand during peak periods. Designers need to make sure to include a pressure drop on key pieces of equipment.
4. Failure to use recovery systems. Using systems that simply exhaust compressed air to atmosphere are highly inefficient. Building systems that can reclaim the energy spent in making high energy compressed air make the above two mistakes easier to overcome.
5. Insufficient storage. The value of an appropriately sized air reservoir is often underestimated. These tanks provide a first stage of moisture separation to help maintain compressed air quality. However, their primary function is storing and delivering compressed air to help meet periods of peak demand and to prevent excessive compressor cycling. Smaller tanks may also be required close to machines or areas where air flow demands may spike or be intermittent.
6. Not taking measures to isolate pressure fluctuations from pressure and flow sensitive need areas. Make sure to add surge tanks and staged regulation.
7. Improper routing. A piping system with tight turns and tee unions may cause pressure loss through turbulence. You want to run the piping as straight and smooth as possible. Care should also be taken about the environment where the piping is routed. You want the air to stay cool to prevent condensation, so the pipes need to be insulated if they must run into a hot room or near a heat source. One of the simplest fixes in a compressed air system is to replace tee connections with directional angle entry connections. In a piping system where a feed line of compressed air is trying to feed into another air line, the turbulence caused by a 90° entry can cause a 3 to 5 psi pressure loss, which increases the operating costs. The back pressure from these tight turns can send a false unload signal to the controls, causing premature unloading or extra compressors to be on line. Using a 30° to 45° directional angle entry instead of a tee will eliminate this pressure loss.
Many thanks to Michael Guelker, Product Manager, Pneumatic Actuators for Festo Corp.; Bimba Mfg.’s engineering team; and Todd Bordewyk, Director of Engineering and Quality for Humphrey Products, for their contributions to this article.
Filed Under: Actuators, Pneumatic Tips, Linear motion • slides, Pneumatic equipment + components