Compressed air represents one of the largest opportunities for immediate energy savings, which accounts for an average of 15% of an industrial facility’s electrical consumption. In fact, over a 10-year period, electricity can make up 76% of the total compressed air system costs.
Monitoring compressed air usage, identifying compressed air waste and inefficiencies, and making investments in new compressed air equipment – including piping – are tangible ways businesses can cut their operating costs by lowering their electricity bill.
Installing Wireless Monitoring Sensors
The right approach to eliminating efficiencies can pay dividends. It’s not uncommon to see typical savings of up to 30% of the energy input to the air compressor. These savings are achievable through initially selecting the most efficient type of air compressor, ensuring the correct air system design and ongoing efficient operation and good maintenance. It also includes maximizing the use of the latest technologies available and also ensuring attention is paid to the simple measures of keeping leakage rates to a minimum.
An excellent place to start is to monitor compressed air usage, which is especially important since proper layout of the compressed system and piping material is often ignored. When this happens it causes the air compressor to work overtime and consume energy unnecessarily.
Pay attention to piping material in a compressed air system to identify areas for improved efficiencies.
Monitoring sensors should be installed to identify where the problem areas are and give a quantifiable data on what needs corrected before any system modifications take place.
The type of monitoring sensor used depends on personal preference. Data can be collected using the traditional analog style sensor, or a wireless sensor that reports data to a cloud-based monitoring platform. Sensor style aside, pressure, humidity, and flow should be collected to create a full health profile of the compressed air system.
Some wireless sensors specifically designed for compressed air system monitoring not only provide the appropriate measurements but also report key data to cloud-based monitoring platforms and access at all times to real-time data. In addition, the latest technology automatically alerts users to readings that fall outside a desired performance band.
Often the best advice is to have a trained compressed air expert identify what sensors are required and where they need to be placed as part of compressed air system assessment.
Humidity sensors in compressed air pipelines alert users to excess moisture in the system.
Monitor and Measure System Pressure
Having an inefficient compressed air system could be costing tens or even hundreds of thousands of dollars in wasted energy per year. These inefficiencies result from several causes, including:
- Inadequately sized piping
- Internal corrosion of the distribution piping
- Too many elbows
- Reductions in pipe diameter
- Wrong sized compressor
- Lack of compressed air storage
Air leaks are often a main source of energy loss in a compressed air system. For instance, a 14.5 psi pressure drop uses 10% additional energy. Also, every 2 psi of compressed air generated equals 1% of a system’s total energy cost.
Any of these issues will cause the air compressor to work overtime, shortening its life expectancy – all of which supports the need for monitoring and measuring compressed air system pressures. Taking pressure readings throughout the compressed air system at key locations: the compressor room, point of use, and the distribution piping will identify if and where these issues exist in the system. Without collecting pressure data at these points, a pressure profile cannot be done to identify the area of pressure drop.
Humidity Readings Uncover Issues with Moisture
The level of humidity must also be monitored and measured. Excess moisture corrodes pipes and damages internal components of machinery, increasing maintenance costs and causing production downtime. In certain applications, the excess moisture can cause product damage resulting in rework and scrap. Moisture also breeds harmful bacteria that will contaminate the finished goods.
Humidity sensors can prevent these issues. Taking humidity readings from the compressed air lines in the compressor room and point of use will determine if a system is operating at peak efficiency. High levels of humidity in a compressed air system can indicate either a problem with the dryer, condensate removal system, or simply the location of the air compressor and dryer.
Flow Sensor Data Can Reveal Multiple Issues
The need to record system airflow cannot be understated. A common cause of inefficient air systems is clogged piping. In traditional piping materials, the interior will corrode over time, restricting the flow of air. Undersized piping will also cause inefficiencies. In some cases, the pipe was sized correctly for the original demand, but as the facility grew in air demand, the piping system became too small to deliver the correct air pressure to the point if use.
Leaks also cause compressed air system inefficiencies. Leaks are mainly seen in older pipes, but newer installations can still leak as well. Eventually, threaded connections start to separate, creating a path for air to escape from the distribution network. Installation mistakes will also lead to leaks, as well as the potential for serious injuries. Aside from measuring and monitoring it’s also important to assemble the system to the manufacturer’s specifications when attaching connectors to avoid leaks and potential injury.
Placing flow sensors at the correct locations in a compressed air system will identify potential leaks, unnecessary or inappropriate uses of compressed air, and the demand of the entire facility and each individual department. The best way to check for system leaks is to monitor the artificial demand of air during idle (no production) times. The higher the artificial demand, the more leaks exist in the system.
Analyzing the data also determines the health of the piping. The interior of pipes will corrode and create blockages without ever showing signs on the outside. An area with poor flow readings means the pipe has begun to corrode.
The Ins and Outs of Proper System Layout
After collecting pressure, humidity, and flow data of your compressed air system, an analysis and redesign of the new system can begin. Making layout modifications can reduce pressure drop, increase flow, and provide better quality of air.
The results may show that new equipment and new piping will be required. A properly designed, maintained and energy efficient compressed air system could save thousands of dollars each year. It will also minimize the risk of lost production by increasing the reliability of supply and improve the strength and safety aspect of operating a pressurized system.
The first step of system redesign is to survey the layout of the pipe system. During your survey look for the following trouble areas.
- Too many elbows
- Abrupt changes in airflow
- Excessive lengths of pipe
- Non-isolated lengths of unused compressed air piping
- Under or Over sized piping
Too many elbows many not be an obvious cause, but the shape of the elbow causes the air to abruptly change direction, losing flow. A way around using too many elbows is to bend the pipe. All diameters (1/2” to 6”) of Parker’s Transair aluminum piping, for example, can be bent due to the Qualicoat-certified finish. Some types of piping can be bent using a conduit bender. For the larger diameters, the pipe needs to be packed with sand prior to bending.
Piping that can be easily bent helps avoid too many elbows in a compressed air system.
Proper support is another key factor in the design of the piping layout. If not supported properly, excessive lengths of pipe will start to sag overtime. This sagging will create sharp bends that compressed air slams into and reduces the flow. When hanging compressed air piping, always use the recommended number of hangers. Some piping allows users to reduce the number of hangers needed. Due to the lightweight aluminum construction, a 20-foot section of Transair, for example, requires only two hangers, versus four or more with traditional systems.
Reducing the sag in piping also eliminates excess moisture from building up in the pipe and causing corrosion and blockage. Piping made of high-grade aluminum alloys used in some piping creates a natural resistance to corrosion in the pipe’s interior. Piping is also available with a strong external barrier to protect against environmental factors that can cause damage to the exterior of the piping.
The Advantages of Aluminum Piping
Replacing worn, steel or copper pipe with aluminum pipe is a good approach for correcting the issues of a compressed air system. Copper and black iron have been the preferred choice for compressed air systems due to the low material costs. However, threaded joints often serve as a source of leakage. To compensate for these leaks, the air compressor starts to work overtime to maintain the necessary flow. This overtime work reduces the life of the air compressor and causes premature failures in the equipment.
Traditional metal systems are also more susceptible to corrosion. Interior corrosion causes scaling and pitting on the inside of the compressed air piping. As the corrosion particles build, blockages in the pipe start to occur, causing more occurrences of pressure drop in the system. The particles can also dislodge and travel to the point of use, causing significant damage to the equipment.
Additionally, the traditional metal systems require specialized labor to install. Due to the need to solder copper pipe, a fire watcher is required to be on-site as the piping is installed. The weight of the pipe also requires additional safety features to me in place. Steel pipe needs to be lifted into place with a pipe lull, but some piping is light enough for one or two workers to move into place just using a scissor lift. Also available is quick connection technology, which eliminates the need for specialized installation labor.
About the Author
Keith Harger is an applications engineer with Parker Hannifin, Parker Fluid System Connectors Division – Transair, tel: 269-760-7570, email: firstname.lastname@example.org.
About Parker Hannifin Transair Piping
With 22 years of experience and over 750,000 installations worldwide, Parker Hannifin’s Transair aluminum pipe system has become the trusted brand for compressed air, vacuum, and inert gas applications. To help with the design of compressed air systems, Parker Transair has developed a suite of tools, including design software, CAD files, energy savings calculator, flow calculator, and BIM design files. For more information, visit www.parker.com/transair.
All photos courtesy of Parker Hannifin.
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