“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:
When I see turbulent flow vs. laminar flow I vaguely remember my fluid dynamics class at the University of Cincinnati. A lot of times when one thinks about the flow of a liquid or compressed gas within a pipe they want to believe that it is always going to be laminar flow. This, however, is not true and there is quite a bit of science that goes into this. Rather than me start with Reynolds number and go through flow within pipes I have found this amazing video from a Mechanical Engineering Professor in California. Luckily for us, they bookmarked some of the major sections. Watch from around the 12:00 mark until around the 20:00 mark. This is the good stuff.
The difference between entrance flow, turbulent flow and laminar flow is shown ideally at around the 20:00 mark. This length of piping that is required in order to achieve laminar flow is one of the main reasons our Digital Flowmeters are required to be installed within a rigid straight section of pipe that has no fittings or bends for 30 diameters in length of the pipe upstream with 5 diameters of pipe in length downstream.
This is so the meter is able to measure the flow of compressed air at the most accurate location due to the fully developed laminar flow. As long as the pipe is straight and does not change diameter, temperature, or have fittings within it then the mass, velocity, Q value all stay the same. The only variable that will change is the pressure over the length of the pipe when it is given a considerable length.
Another great visualization of laminar vs. turbulent flow, check out this great video.
If you would like to discuss the laminar and turbulent flow please contact an Application Engineer.
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 Second Step to optimize your compressed air system is to Find and fix leaks in your compressed air system. The reason leaks are important to find and fix is because they can account for 20-30% of a compressors total output. A compressed air leak fixing process can save 10-20% of that lost volume.
Unintentional leaks will result in increased maintenance issues and can be found in any part of a compressed air system. Leaks can be found at a poorly sealed fitting, quick disconnects and even right through old or poorly maintained supply piping. Good practice will be to develop an ongoing leak detection program.
The critical steps needed for an effective leak detection program are as follows:
Get a foundation (baseline) for your compressed air use so you have something to compare once you begin eliminating leaks. This will allow you to quantify the savings.
Estimate how much air you are currently losing to air leaks. This can be done by using one of two methods.
Load/Unload systems, where T= Time fully loaded and t=Time fully unloaded:
Leakage percent = T x 100
(T + t)
Systems with other controls where V=cubic feet, P1 and P2=PSIG, and T=minutes
Leakage = V x (P1-P2) x 1.25
T x 14.7
Know your cost of compressed air so you can provide effectiveness of the leak fixing process.
Find, Document and Fix the leaks. Start by fixing the worst offenders, fix the largest leaks. Document both the leaks found and the leaks fixed which can help illustrate problem areas or repeat offenders, which could indicate other problems within the system.
Compare the baseline to your final results.
Repeat. We know you didn’t want to hear this but it will be necessary to continue an efficient compressed air system in your plant.