Advantages of Thermal Mass or Thermal Dispersion Flow Measurement

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.

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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.

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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.

Advantages

  • Easy to install – No cutting or welding required
  • Summing Remote Display and Data Logger available
  • Sensitive at low flows
  • Rugged, reliable and no moving parts
  • No calibration or set-up required
  • Models from 1/2″ to 4″ schedule 40 iron pipe in stock
  • Short lead time for sizes up to 6″ Schedule 40 iron pipe
  • Available for size 3/4″ to 4″ copper pipe
  • New Wireless Capability

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.

Brian Bergmann
Application Engineer

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Digital Flowmeter Improves Production Scheduling And Upgrade Budgeting

“You can’t manage what you can’t measure” might be the most popular axiom in any process improvement endeavor. And it’s true. We hear it almost every time we discuss a Digital Flowmeter application, and a conversation I just had with a customer was no exception.

Their business is growing, and they’re pushing the limits of their compressed air system. The use compressed air to run their CNC mills in their machine shop, for blow off/cleaning as they assemble products, as well as a variety of pneumatic tools throughout the shop. The CNC machines’ air load was pretty consistent…the rest of the shop; not so much. So they wanted to find out when their compressed air demand peaked, and what it peaked at, in order to make a more informed decision about upgrading their compressor.

From your Digital Flowmeter to your computer screen, the USB Data Logger tells you how much air you’re using…and when you’re using it!

So, they purchased a Model 9095-DAT Digital Flowmeter for 2″ SCH40 Pipe, with USB Data Logger. They installed it immediately, with the USB Data Logger set to record once a second…this told them their consumption at any given time over the course of the day. Every day at closing time, the shop manager pulls the USB Data Logger from the Digital Flowmeter and transfers the data to his computer. After just a few days, he knew exactly how much air they were using…and exactly when they were using it. He’s now using this data (in the short term) to plan certain operations around peak scheduling, and (in the long term) to know what they’re looking at for their next air compressor.

Do you know as much about your compressed air usage as you should? If you’d like to talk about how to measure…and manage…your air consumption, give me a call.

Russ Bowman
Application Engineer
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