When evaluating processes that utilize compressed air and adhering to the Six Steps to Compressed Air Optimization, intermediate storage proves to be a critical role coming in at step number five. Intermediate storage tanks may already be in place within your facility and often times can be implemented as modifications to aid existing lines that are struggling to maintain proper availability of compressed air to keep the line at peak performance.
When determining whether or not a production line or point of use compressed air operation would benefit from a receiver tank/intermediate storage we would want to evaluate whether the demand for compressed air is intermittent. Think of a receiver tank as a capacitor in an electrical circuit or a surge tank in a water piping system. These both store up energy or water respectively to deliver to during a short high demand period then slowly charge back up from the main system and prepare for the next high demand. If you look from the supply point it will see a very flattened demand curve, if you look from the application side it still shows a wave of peak use to no use.
One of the key factors in intermediate storage of compressed air is to appropriately size the tank for the supply side of the system as well as the demand of the application. The good news is there are equations for this. To determine the capacity, use the equation shown below which is slightly different from sizing your main compressed air storage tank. The formulate shown below is an example.
V – Volume of receiver tank (ft3 / cubic feet)
T – Time interval (minutes)
C – Air demand for system (cubic feet per minute)
Cap – Supply value of inlet pipe (cubic feet per minute)
Pa – Absolute atmospheric pressure (PSIA)
P1 – Header Pressure (PSIG)
P2 – Regulated Pressure (PSIG)
One of the main factors when sizing point of use intermediate storage is, they are being supplied air by smaller branch lines which cannot carry large capacities of air. That limits your Cap value. The only way to decrease the V solution is to increase your Cap. The other key point is to ensure that all restrictions feeding into the tank and from the tank to your point of use are minimized in order to maintain peak performance.
The history of automated controls can be traced back to inventors in ancient Greece & Egypt, who sought ways to keep more accurate track of time than afforded by sundials and hourglasses. Their efforts, dating as far back as 300BC, produced devices actuated by water flow, which is actually quite reliable and repeatable: a set amount of water will flow via gravity through a fixed conduit in the exact same amount of time, every time. These were in fairly common use until the invention of the mechanical clock in the 14th century.
The Industrial Revolution grew the need for automated processes exponentially…the need to control objects or tooling in motion, fluid flow, temperature, and pressure, just to name a few. As time passed, the sky was literally the limit: modern aircraft & spacecraft rely on a staggering amount of automated processes from production to operation.
All throughout history, though, the benefits of automation remain the same: making processes more efficient. That’s where the EXAIR EFC Electronic Flow Control comes in, for automating processes involving compressed air use, by turning air flow off when it’s not needed. In fact, not only do they provide simple on/off control to blow only when a part is “seen” by the photoelectric sensor, there are eight distinct modes to incorporate delay on or off, flicker on or off, signal on/off delay, interval, or “One-Shot,” where the sensor detects the part, delays opening the valve per the timer setting, and blows for one second.
The EXAIR EFC Electronic Flow Control is a true “plug and play” solution for automating a compressed air application. Mount the sensor, plumb the valve, plug it in, and you’re ready to go. There’s no complicated PLC wiring or programming, although the aforementioned mode selections do offer a great deal of flexibility other than “on when the sensor sees it; off when it doesn’t” operation, if desired. Here are some prime examples of that flexibility, and the monetary benefits due to the compressed air consumption savings:
(Left) On/Off Delay setting used in tank refurbishment application to operate a “halo” of Super Air Knives for blow off as tanks exit oven where old paint is burnt off – $3,393 annual air savings. (Center) Interval setting actuates a Super Ion Air Knife for flat panel display dust blow off/static elimination – $2,045 annual air savings. (Right) Interval setting actuates a “halo” of Super Ion Air Knives to clean & remove static charge from plastic automotive bumper covers prior to painting – $5012 annual savings.
All compressed air systems will have some amount of leakage. It is a good idea to set up a Leak Prevention Program. Keeping the leakage losses to a minimum will save on compressed air generation costs, and reduce compressor operation time which can extend its life and lower maintenance costs.
The Compressed Air Challenge estimates an individual compressed air leak can cost thousands of dollars per year when using $0.07/kWh.
1/16″ diameter hole in excess of $700/year
1/8″ hole in excess of $2900/year
1/4″ hole in excess of $11,735 per year
There are generally two types of leak prevention programs:
Leak Tag type programs
Seek-and-Repair type programs
Of the two types, the easiest would be the Seek-and-Repair method. It involves finding leaks and then repairing them immediately. For the Leak Tag method, a leak is identified, tagged, and then logged for repair at the next opportune time.
A successful Leak Prevention Program consists of several important components:
Document your Starting Compressed Air Use – knowing the initial compressed air usage will allow for comparison after the program has been followed for measured improvement.
Establishment of initial leak loss – See this blog for more details.
Determine the cost of air leaks – One of the most important components of the program. The cost of leaks can be used to track the savings as well as promote the importance of the program. Also a tool to obtain the needed resources to perform the program.
Find the leaks – Leaks can be found using many methods. Most common is the use of an Ultrasonic Leak Detector, like the EXAIRModel 9061. See this blog for more details. An inexpensive handheld meter will locate a leak and indicate the size of the leak.
Record the leaks – Note the location and type, its size, and estimated cost. Leak tags can be used, but a master leak list is best. Under Seek-and-Repair type, leaks should still be noted in order to track the number and effectiveness of the program.
Plan to repairs leaks – Make this a priority and prioritize the leaks. Typically fix the biggest leaks first, unless operations prevent access to these leaks until a suitable time.
Record the repairs – By putting a cost with each leak and keeping track of the total savings, it is possible to provide proof of the program effectiveness and garner additional support for keeping the program going. Also, it is possible to find trends and recurring problems that will need a more permanent solution.
Compare and publish results – Comparing the original baseline to the current system results will provide a measure of the effectiveness of the program and the calculate a cost savings. The results are to be shared with management to validate the program and ensure the program will continue.
Repeat As Needed – If the results are not satisfactory, perform the process again. Also, new leaks can develop, so a periodic review should be performed to achieve and maintain maximum system efficiency.
An effective compressed air system leak prevention and repair program is critical in sustaining the efficiency, reliability, and cost effectiveness of an compressed air system.
If you have questions about a Leak Prevention Program or any of the 16 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.
“You can’t manage what you don’t measure” is a well-known axiom in engineering & process improvement circles. We talk to callers every day who are keen on conserving compressed air use in their facilities by making a few tweaks, considering a complete overhaul, or more often, some point in between. Bottom line (literally) is, compressed air isn’t cheap, so small gains in efficiency can add up. And large gains can be complete game-changers…following our Six Steps To Optimizing Your Compressed Air System has resulted in users being able to shut down 50 and 100 HP air compressors, saving thousands of dollar A MONTH in operating costs.
Step #1 is measurement, and that’s where the EXAIR Digital Flowmeter comes in. They’re easy to install, highly accurate, extremely reliable, and available for just about any size pipe used for compressed air distribution. They can output a 4-20mA signal straight from their PCB board, or serial comms (RS485) through an optional control board. USB Data Loggers and Summing Remote Displays have proven to be value-added accessories for data management as well.
If you want to go wireless, we can do that too: using ZigBee mesh network protocol, a radio module is installed in the Digital Flowmeter with wireless gateway to transmit data to an Ethernet connected gateway. The transmitting range is 100 ft (30 meters,) and the data can be passed from one radio module to another, allowing for multiple Digital Flowmeter installations to extend the distance over which they can communicate with the computer you’re using for central monitoring. Advantages include:
Since air compressors use a lot of electricity to make compressed air, it is important to use the compressed air as efficiently as possible. EXAIR has six simple steps to optimize your compressed air system. Following these steps will help you to cut electrical costs, reduce overhead, and improve your bottom line. In this blog, I will cover the first step – Measure the air consumption to find sources that use a lot of compressed air.
Information is important to diagnose wasteful and problematic areas within your compressed air system. To measure air consumption, flow meters are used to find the volume or mass of compressed air per unit of time. Flow rates are very useful data points to find problems like leaks, over-use in blow-offs, waste calculations, and comparison analysis.
There are many different types of flow meters. Many of them entail a breakdown of your current compressed air lines by cutting, welding, or dismantling for installation. This will add cost in downtime and maintenance staff. But, not with the EXAIR Digital Flowmeters. In this blog, I will share the features and benefits of the Digital Flowmeters including options for you to start measuring and optimizing your compressed air system in Step 1.
Overall, it only takes a few minutes to install and start measuring. The installation kit comes with a drill bit and a drill guide to properly locate the two holes on the pipe. The Digital Flowmeter uses a clamp to mount to the pipe and to seal the area around the probes. Once it is powered, the unit is ready to measure the air flow inside the pipe with a large LED display. The display can be customized to show flow readings in three different units; SCFM, M3/hr or M3/min; and, it can display the Daily Usage and Cumulative Usage.
To get started, the EXAIR Digital Flowmeter is a thermal dispersion device that can accurately measure compressed air flows. They use two sensing probes for comparative analysis. One probe is a temperature sensing probe, and the other is a flow-sensing probe. By comparing these, the Digital Flowmeter can measure precisely the mass air flow without needing to be recalibrated. They are a cost-effective, accurate, and simple way to measure compressed air flows.
EXAIR stocks a large volume of Digital Flowmeters to ship same day for U.S. and Canadian customers. We also offer a 30-day unconditional guarantee to try them out. We stock meters for pipe diameters from ½” NPT to 4″ NPT Schedule 40 black pipe. EXAIR can also offers flow meters up to 8″ NPT black pipe; copper pipes with diameters from 3/4″ to 4″, and aluminum pipes with diameters ranging from 40mm to 101mm. If you have another type of piping for your compressed air system, you can give us the material, O.D. or I.D., and wall thickness. We may still be able to get a Digital Flowmeter for you.
For measuring, all the units come standard with a 4 – 20mA analog output. Per your request, we can change this signal to a serial output for RS-485 or Ethernet connections. What more can we offer with the EXAIR Digital Flowmeter? Options. Options upgrade the flow meters to better suit your application. Here is a list below:
USB Data Logger: This option allows for a recording of the flow information. With a software download, you can setup the USB Data Logger to record the flows from once a second (roughly 9 hours of storage) to every 12 hours. After the data points are recorded, you can then download the information into the software to review. Then the information can be uploaded into an Excel program to do further analysis.
Summing Remote: With compressed air pipes running along the ceiling and walls, reading the Digital Flowmeter may be difficult. The Summing Remote has a 50-foot (15 meter) cable to bring the LED display into viewing. The Summing Remote is powered by the Digital Flowmeter, and it can be positioned at eye level, inside managers’ rooms, or around large equipment for monitoring.
Wireless Capability: Our latest Digital Flowmeter now has wireless capabilities. They use a Zigbee® communications to pick up flow readings from other flow meters and the Gateway. The Gateway can detect over 100 Digital Flowmeters in your facility. From the Gateway, the information is transferred through a LAN. You can record and analyze the flow information from each meter on the network with our EXAIR® Logger Software. You can set limits to send warnings when your compressed air system is using too much or too little of compressed air. This technology makes it very easy for measuring your compressed air system in the entire facility without having to be there.
Hot Tap Digital Flowmeter: This option is a great way to install a Digital Flowmeter to the pipe without shutting down the compressed air line. We offer this option for 2″ and larger flow meters for steel and copper pipes. It gives a quick and easy way to attach if you have a 24-hour operation or a critical process that needs to continue to run.
Pressure Sensing Digital Flowmeter: If you would like to know the compressed air flow and the air pressure, this option will be able to do this. They are available with the Digital Flowmeters for steel and copper pipes that are 2″ and larger, and for the aluminum piping that is 50mm and larger. This option can display pressure units in either PSI or Bar right on the same LED display that shows the flow readings.
Block-Off Rings: If you want to move your Digital Flowmeter, the Block-Off Rings will be able to cover the openings in your compressed air pipe. They seal around the drilled opening when the Digital Flowmeter is removed from the pipe. They are reusable; so, they can be removed if you want to remount the Digital Flowmeter in the same spot. If you want to use one flow meter in different locations, the Block-Off Rings allow you do this.
When you need to analyze your pneumatic components, flow is an important point in diagnosing the overall “health” of your compressed air system. The EXAIR Digital Flowmeter can give you that important data point. With optimization, you can cut your energy consumption, improve pneumatic efficiencies, and save yourself money. This blog is an overview of Step 1 of six steps. You may have more questions; and, that is great! You can find them in other EXAIR blogs, or you can contact an Application Engineer at EXAIR.
The Electronic Flow Control, or EFC, is an EXAIR Optimization product to reduce air consumption in your facility. Saving this electricity that is used to make compressed air will save you money and will help you to “Go Green”. The EFC has 8 different modes that uses a timing sequence with a Photoelectric Sensor to turn on/off a solenoid valve. In this video, I will go through each mode to demonstrate how the Electronic Flow Control will perform.
The 5th step in the 6 steps to optimizing your compressed air system highlights the use of intermediate storage of compressed air near the point of use. Secondary, or intermediate Receiver tanks are installed in the distribution system to provide a source of compressed air close to the point of use, rather than relying on the output of the compressor.
Compressed air receiver tanks are an integral part to many compressed air distribution systems. Compressed air is stored at a high pressure after drying and filtration, but just upstream of point of use devices. The receiver tank is charged to a pressure higher than what is needed by the system, creating a favorable pressure differential to release compressed air when needed.
Think of a compressed air receiver tank as a “battery”. It stores the compressed air energy within a system to be used in periods of peak demand, helping to maintain a stable compressed air pressure. This improves the overall performance of the compressed air system and helps to prevent pressure drop.
They can be strategically placed to provide a source of compressed air to intermittent high volume compressed air applications. Rather than having to pull from the compressor, a receiver tank can be sized to provide the short-term volume of air for a particular application. In a previous post, we’ve highlighted how to calculate the necessary receiver tank based on the air consumption and duration of the application.
EXAIR offers from stock a 60-gallon receiver tank designed specifically for these higher-usage intermittent types of applications. Model 9500-60 can be installed near the point of high demand so that you have an additional supply of compressed air available for a short duration. The tank comes with mounting feet and is designed to stand up vertically, saving floor space. The tank meets American Society of Mechanical Engineers (ASME) pressure vessel code.
If you have an application in your facility that’s draining your compressed air system, a receiver tank could be the ideal solution. Give us a call and one of our Application Engineers will be happy to help evaluate your process and determine the most suitably sized receiver tank.