Tools Of The Trade: The Rotameter

EXAIR’s Free Efficiency Lab

One of the free services we offer to customers here at EXAIR is our Efficiency Lab. In case you are not familiar here is a brief synopsis. Speak with an Application Engineer about your existing compressed air blowoff/point of use product and that you would like to know how much air it consumes. Fill out the brief survey and send the product you use in to our facility. Let us perform tests on calibrated test equipment to determine the force, flow, and noise level. We will then issue you a report that states what the EXAIR model would best be suited (if applicable) as well as how much compressed air you will be able to save. Order the recommendation and start saving money.

To do these evaluations, we have to have calibrated equipment that is reliable and capable of handling vast range of products we may receive in. For this, we could use a Digital Flowmeter, in some cases that is what has to be done due to large flow rates. For the majority of these though we go old school. We utilize a piece of equipment called a rotameter.

A rotameter pairs nicely with a calibrated pressure gauge as well.
The float can be seen with graduated marks for readings. The taper of the chamber is not easily seen with the naked eye.

This is a device that is designed to measure the flow rate of a fluid within a closed tube. The inside diameter of the tube is varied which causes the float within the meter to raise or lower.  They are calibrated for a specific gas at a given pressure and temperature, most are calibrated for atmospheric conditions, 14.7 psi (1.014 Bar). The meter must be mounted vertically and this is not always best suited for industrial environments.

When testing products the compressed air within the meter is pressurized which means we have to correct the reading for the given pressure, if the temperature is outside of the calibration temp then we must also perform that correction. We do this using a table provided by the manufacturer of the meter or by using the calculations shown to get exact values that may be in between the pressures in the table.

Pressure Correction Table

 

This will allow us to then multiply the Correction Factor by the meter reading and calculate our corrected flow for the point of use device at a given operating pressure and temperature.

Temperature correction table

Knowing where the values that are measured and calculated come from add validity to the reports and understanding all of the variables that go into reading like this helps to better validate the cost savings that can be seen.

In a pinch, for a field estimation, we can also use these Correction Factors and determine an approximate consumption rate of a device that has been measured at a pressure such as our cataloged 80 psig (5.5 Bar). This can often be done on the fly to help determine the flowrates currently on a system. This can be helpful when troubleshooting, giving estimated simple ROIs, and help justify results and reasons for future purchases of engineered solutions.

If you want to discuss the Efficiency Lab or any of the math behind our calculations, contact any Application Engineer, we can all help out.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

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
Find us on the Web
Follow me on Twitter
Like us on Facebook