EXAIR’s Digital Flow Meter offers an easy way to measure, monitor and record compressed air consumption. The Digital display shows the current amount of compressed air flow, allowing for tracking to identify costly leaks and/or inefficient air users.
How exactly does the Digital Flow Meter work? The unit falls under the category of Thermal Mass or Thermal Dispersion type flow meters. Below shows the backside of a unit.
Thermal mass flow meters have the advantage of using a simple method of measuring flow without causing a significant pressure drop. The EXAIR units have (2) probes that are inserted through the pipe wall and into the air flow. Each of the probes has a resistance temperature detector (RTD.) One of the probes measures the temperature of the air flow. The other probe is heated to maintain a preset temperature difference from the temperature measured by the first probe. The faster the air flow, the more heat that is required to keep the second probe at the prescribed temperature. From Heat Transfer principles, the heat energy input required to maintain the preset temperature is based on the mass velocity of the air. Using basic physical properties for compressed air, the volumetric rate can be determined (SCFM), and displayed.
It is important to note that the compressed air should be filtered to remove oils, and dried to remove water, as these liquids have different physical properties from air, and will cause erroneous readings.
If you have any questions about the Digital Flow Meter or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
Being an Application Engineer at EXAIR you tend to do a good amount of return on investment (ROI) calculations. This is mainly to tell customers just how fast installing an EXAIR product on their system is going to pay its purchase price back and start saving them money.
In order to do these calculations there are several variables we must know. The list is below.
Current Product Consumption (If this is an unknown, we will test it for free!)
Cost of Compressed Air / 1,000 SCF (This is the most common unknown.)
With these four variables we can calculate the amount of air and the amount of money the EXAIR product will save over an existing non-engineered blowoff. Let me address the two variables which have to come from you, the customer.
Current Product Consumption – If this value is not known please don’t guess at it. We offer a free service which we refer to as our Efficiency Lab where you send us in your existing blowoff device and we will test it for force flow and noise level. If you don’t know what pressure you are operating the piece at we will help you find out how to get that and then we will test our products at the same pressures. This way you get a true apple to apples comparison. Then, once we are done testing, you will get a recommendation from us in a formal report as to what EXAIR product will best replace your existing product. Then we will pay for return shipping of your blowoff device back to you. So, if you don’t know how much air you are currently using then give us a call. We will figure it out for you.
Cost of Compressed Air/ 1,000 SCF – This is more often than not, the unknown variable in the equation. The good news is there is a general standard assumption of twenty-five cents per 1,000 Standard Cubic Feet of compressed air. This works out to be around 8 cents per kW/hr. So even if you don’t know what you pay to compress the air, if you know what you are paying per kilowatt hour for your energy then we can calculate within reason what it costs for you to generate your compressed air. For reference, 8 cents per kilowatt-hour falls between the average US cost per kilowatt hour for commercial end-users (10.7/kWh) and industrial end-users (6.9/kWh).*
The best part of all is…EXAIR has a calculator available right on our website which provides air and dollar savings per minute, hour day and year as well as a payback in days for the EXAIR product purchase. On top of that, any step along the way that you aren’t sure of, we will help you out for free, even testing your product!
In case you would like to see the math, the formula used is below.
Quick Disconnects are a quick and easy solution to hook up devices to your compressed air system. These units can be found in quite a few factories and are more often than not being used incorrectly. I know that on the air compressor in my garage, the only way to hook anything up to it was to use 1/4″ quick disconnects. Chances are they are even a few of them within your facility, assuming you have compressed air available.
When you really look at a quick disconnect though you start to see why it shouldn’t be used to install every compressed air driven device there is. You can see in the pictures below that a 1/4″ quick disconnect that goes to a 3/8″ NPT adapter has a .192″ opening at the small end. A 3/8″ Schedule 40 iron pipe will actually carry a .493″ inner diameter. If you were to use this quick disconnect on something like a 2″ Heavy Duty Line Vac, you will starve it for air due to the limited ability of the small diameter to carry enough air volume. This, in turn, will limit the performance of the Line Vac. This is because the through hole on the quick disconnect cannot pass enough air to feed through to the Line Vac.
On the 1/4″ quick disconnect to a 3/8″ NPT this may not be as large as a problem as the next picture. Below you can see a 1/2″ quick disconnect that is going up to a 3/4″ NPT. a 3/4″NPT Schedule 40 iron pipe is actually a .824″ inner diameter. The quick disconnect at most has a .401″ inner diameter.
Even though you are providing the correct thread size for your connection (a 3/8 MNPT and a 3/4 FNPT respectively in our example) the quick disconnect’s small inside diameter could be too much of a restriction for the volume demanded by an end use product. Due to this restriction point you will see pressure drops in your system when using a device with a properly sized inlet for its demand of compressed air being fed with an improperly sized quick disconnect. This is one of the main reasons one of our first questions in troubleshooting an EXAIR products performance with a customer is whether or not they are using quick disconnects.
With all the talk of conserving energy and lowering our energy consumption going around, optimization of your compressed air system is vital to reducing the consumption your operations use. One of the key ways you can optimize your system is by implementing an Electronic Flow Control wherever possible.
The advantage to using an EFC on your system is you will decrease your air consumption as long as your process can be shut off for even a second or less. Think of the grass in your yard. You don’t water it continuously throughout the day like in the video below.
Come to think of it I’m not sure I have ever seen someone water their lawn quite like that…back to the point. When most people water their lawn they only use the water when the yard needs it or for a set time, this is achieved with devices like the following video portrays.
This is one of the ways to “Optimize” the system so that water is not being wasted. The EXAIR EFC offers the same type of control for your compressed air operations. Whether it is blowing parts off as they come down a conveyor line, sucking up some trim or debris on a given interval, or even ejecting parts from a line, the EFC has dozens of programmable modes and offers the conservation of your compressed air.
For example if you run a conveyor with products that need to be blow off and are 6” long, have a 6” gap between each product you could set the sensor and the timing unit for the EFC to save up to 50% of your compressed air. There have been multiple uses across multiple industries that have saved thousands of dollars for our customers. To check out some of the applications where the EFC has cut air consumption please follow this link.
I recently had a customer contact me asking about some of our products, mainly our small Air Nozzles. When asked what their application was for the nozzles I learned they were trying to reduce their Air consumption and had no idea what their current system was using. I mentioned that we offer the EXAIR Efficiency Lab which is a free service where you can send your existing nozzles or blow off to us and we will evaluate it in our lab then recommend an EXAIR product that will improve the current system.
After explaining this all to the customer they said they are going through an entire system audit and this would be perfect for their needs. I gave them the information and within a few days I had the nozzles, shown below, on my desk with a letter of what application each nozzle has and also what their operating pressure is.
The customer explained to me that they are using the aluminum block in several different applications, one as a blow off, one as a product kicker, and one to help stir up dust so a vacuum can remove it. I then went to the Efficiency Lab and performed a test run on the aluminum block. I performed the test several times at 90 PSIG to ensure my data was legitimate. The block was flowing 19.75 SCFM of compressed air, giving off 103 dBA at three feet away from the block and approximately one pound of force.
I took this information and cross referenced our catalog. With the application descriptions for the block and the flow data I determined that our Adjustable Air Jet Model 6019 would be an easy substitution for their aluminum block. This would keep the one pound of force they were using to help move the product along with blow it off while only using 18 SCFM at 80 PSIG and emit 83 dBA. On top of the fact that our Engineered Adjustable Air Jet meets or exceeds the OSHA requirements for dead ended pressure, which means they will not have the risk of an operator getting injured with the compressed air from the jet.
The second blow off they were using is a copper pipe that has to be manually welded to a fitting. This blow off was used to assist in both part blow off and moving the part down a line. The pipe would consume 8.54 SCFM at 90 PSIG with .5 lbs. of force while emitting 86 dBA. Our comparable nozzle would be the 1110SS which will consume 8.3 SCFM at 80 PSIG with .5 pounds of force and only emit 75 dBA. This nozzle like all of our nozzles meets or exceeds OSHA requirements for dead ended pressure. Also they will still save compressed air while running a lower pressure and noise level.
The final blow off the customer sent is a small inner diameter stainless steel pipe that was consuming 2.14 SCFM at 90 psi while giving off .5 pounds of force and emitting 70 dBA. For a solution to this blow off we suggested our 1010SS Micro Air Nozzle with the pressure regulated down to match similar flow characteristics of the small pipe. This allowed us to maintain performance while still lowering noise and meeting the OSHA dead-end pressure standard.
With several machines in place and dozens of nozzles there is a large potential to cut energy costs along with make the shop quieter and help with OSHA compliance. If you have a blow off system that you aren’t sure if it’s the best method please take the time to look at our Efficiency Lab. We are here to help you with not just new applications but to improve existing ones also.