“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:
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.