Digital Flowmeters: Converting Them to Serial Communication

Model 9090-DAT

An international customer purchased three Digital Flowmeters, model 9090-DAT in yr2018.  This model number refers to the EXAIR Rev3 Digital Flowmeter with a Datalogger (photo above) for ½” Schedule 40 black pipe.  They used the Datalogger to log flowrates for their blow-molding machines.  A new engineering manager joined their team and was looking for a more “real time” reading of the flowrates.  They could compare flow data results from prior setups to monitor the program for their current blow-molded products with certain materials and sizes.  It was important for quality control to measure and compare the results to verify the proper machine set points.  They contacted EXAIR to see what we could offer.

EXAIR offers a variety of Digital Flowmeters for black pipe, aluminum tubes, and copper pipes.  They can accurately measure compressed air and nitrogen flow by measuring the temperature difference between the two probes.  The display is large for easy reading, and it can be programed for different units like SCFM, M3/hr, and M3/min.  For software data collection, we have the Wireless communication, USB Datalogger, and wire communication.  We also have Hot Tap versions, Pressure measuring, and Remote Display. 

In describing their current programming system, they were using a Modbus RS485 network.  This type of network system uses a “master” device to communicate with multiple “slave” devices.  In this instance, they were going to use a computer as the “master” device to communicate with the Digital Flowmeters.  With this type of serial communication, each Digital Flowmeter would have a particular and exclusive node address.  The master device can “open” the serial communication with that particular Digital Flowmeter and transfer data points of flow measurements.  The serial boards that EXAIR uses can connect to over 100 meters with a total length of 4,000 feet (1,212 meters).

Now, for our customer above, they did not need to purchase different Digital Flowmeters.  EXAIR offers a model 901785 serial communication board to convert the standard Rev3 Digital Flowmeter to connect to Modbus RS485.  They purchased three of them and converted each unit that they had without removing them from the compressed air system.  Since they were using the serial communication to connect to a computer, they requested an Ethernet connection.  EXAIR is able to convert serial communication to either Ethernet or USB connection with a converter.  With the Ethernet converter, they were able to connect directly to their computer.  They downloaded a software program at no charge to start monitoring and collecting flow information from all the digital flowmeters.  This improved the setup times for each machine.  As an extra bonus, they could also determine if they had some pneumatic issues with valves, cylinders, or leaks with the readings from the Digital Flowmeters. 

EXAIR Digital Flowmeters for large pipe

When you need to analyze your pneumatic components, flow is an important point.  The EXAIR Digital Flowmeter can give you that important data point.  You can cut energy consumption, improve pneumatic efficiencies, reduce setup times, and save yourself money.  If you are missing that detail with your pneumatic system, an Application Engineer at EXAIR can help you select the best Digital Flowmeter.  And if in the future you wish to upgrade, we may have a simple solution for you as seen with our international customer above. 

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Find It, Tag It, Fix It: Addressing Parasitic Draw

Leeks, and not the compressed air kind!

Leaks, and not the kind you see on a cooking show, are never good. Before you comment, yes I know the vegetable is spelled leek, that’s just the strength of my dad jokes. The point of this post is actually discussing leaks, mainly of the compressed air variety. All leaks cost. I recently found a leak within my home which was accounting for around a 20% increase in my water bill. Sad to say that it took a few months to locate, and solve the issue. Over the years, I’ve seen many facilities deal with common leak problems like being unable to leave their compressed air pipes energized over night because the parasitic draw will drain the entire system. That’s a problem!

Burst pipes and leaks are ALWAYS costly!

If the leaks are present when nothing is being utilized, then that means parasitic draw is happening on the system. This is when energy that is being converted into compressed air isn’t used but instead, leaking out to atmospheric conditions. These parasitic draws are not always easy to locate, so over the years I’ve had to help a few customers address this problem. One in particular stands out, so I am going to share how we honed in on the leak and ultimately gave them days without a shutdown.

The conversation all started with a customer asking about how our Digital Flowmeters work, and if they could be used to determine which production line is using the most air, and more importantly why their production line shuts down for low air pressure. After I explained how we would select their infeed pipe size as well as size a meter that would fit each machine infeed, we got to talking about the shut down sequence.

The approach they took to solving the issue was to first capture the flowrate of the entire system and then to evaluate the flowrates of each segment of their plant. From there, we would install flowmeters on the higher usage sectors, and drill down to each machine for the finite analysis. They could then go through all the other production lines and generate a full facility consumption profile. To start, they found one packaging line that was using a considerably higher volume of air throughout their first shift than any other line and than any other shift.

Once they started breaking down the high demand production line they found one leg of the production line which had a spike in usage at the same time every day. The trick was they couldn’t find a machine with high usage, that is until they traced all of the piping and found a filter bag house on the roof that had been added to the line at some point. This wasn’t documented and had a piece of pipe that had failed causing an open dump during the cleaning cycle every day at 2:30 in the afternoon.

This was all made possible by setting up multiple flowmeters with wireless capabilities so they could document and compare the usages between machines and production lines ultimately giving them a considerable amount of production time back into the day by fixing a broken pipe that caused daily shutdowns.

If you would like to discuss how to layout a compressed air monitoring system in your facility or the best way to track down the cause of some leaks and high compressed air demand, contact an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Leeks on shelf – Jeffery Martin, CC0, via Wikimedia Commons – retrieved from – https://commons.wikimedia.org/wiki/user:Veronicasgardentracker

Video Blog: How To Remove, or Move, A Digital Flowmeter By Using Block-off Rings

If you need to remove (or move) a Digital Flowmeter, EXAIR has Block-off Rings that are used to safely cover & seal the holes that were drilled in the pipe for installation. Here’s how they work:

If you’ve got any questions about Block-off Rings, Digital Flowmeters, or would like to find out more about EXAIR Corporation can help you get the most out of your compressed air system, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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About Rotary Screw Air Compressors

What is an air compressor? In simple terms it is a machine that increases fluid pressure, it works by changing the volume of air and storing it in a storage tank. Many industries use compressors to increase production and thus has led to the development of many new industries. There are a couple types of air compressors but today I will focus on the Rotary Compressor.

The Rotary Screw Compressor is a very common type of air compressor. This compressor uses dual rotors with meshing lobes that trap air while rotating. The rotation continues to push air toward a discharge port while decreasing the space the air take sup, thus increasing pressure. The rotary compressor has a simple structure with few components and has some clear advantages over other compressors:

  • Longevity
  • When operating, they are quiet
  • Low vibration
  • Continuous operation, or they can match demand

Some disadvantages include:

  • Skilled maintenance required compared to other compressors.
  • They are more expensive than other compressors

There are two types of rotary air compressors. They are oil-injected and oil-free rotary air compressors. Oil-injected rotary screw compressors as the name suggests has oil injected in the compressor element during the air compression. An insignificant amount of oil will escape into the compressed air system also known as “oil carryover”. The use of EXAIRs oil removing filters and filter separators will help remove the oil, moisture and other particulates from the compressed air lines resulting in clean compressed air.

Oil-free rotary screw compressors are similar to the oil-injected compressor but without the use of oil. The oil-free compressors use a two stage system with a cooling process between stages as the compressed air will become extremely hot if not for a cooling process between stages of compression. The oil-free compressors are commonly used in food and medical industries.

EXAIR is here to help with your “Intelligent Compressed Air Products” so please contact us with your compressed air tooling needs.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@EXAIR.com
Twitter: @EXAIR_EK

File:IngersollRand R-series-R110.jpg image is licensed under the Creative Commons Attribution 3.0 License.