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

EXAIR’s Return on Investment For One Engineered Air Nozzle is Amazing!

Return on Investment (ROI) is a measure of the gain (preferably) or loss generated relative to the amount of money that was invested.  ROI is typically expressed as a percentage and is generally used for financial decisions, examining the profitability of a company, or comparing different investments.  It can also be used to evaluate a project or process improvement to decide whether spending money on a project makes sense.  The formula is shown below-

ROI Calculation
  • A negative ROI says the project would result in an overall loss of money
  • An ROI at zero is neither a loss or gain scenario
  • A positive ROI is a beneficial result, and the larger the value the greater the gain
Our catalog publishes most products’ performance and specification data for a compressed air supply pressure of 80psig.

Example – installing a Super Air Nozzles (14 SCFM compressed air consumption) in place of 1/4″ open pipe (33 SCFM of air consumption consumption) .  Using the Cost Savings Calculator on the EXAIR website, model 1100 nozzle will save $1,710 in energy costs. The model 1100 nozzle costs $42, assuming a $5 compression fitting and $45 in labor to install, the result is a Cost of Investment of $92.00. The ROI calculation for Year one is-


ROI = 1,759% – a very large and positive value.  Payback time is only 13 working days!

If you have questions regarding ROI and need help in determining the gain and cost from invest values for a project that includes an EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

Send me an email
Find us on the Web 
Like us on Facebook
Twitter: @EXAIR_JS

How Lowering Sound Levels Produces ROI

Sound levels and ROI don’t immediately link together in a quick thought. Unless you are me and things seem to link up that don’t always go together, like peanut butter and a cheese burger. (Trust me, just try it, or if you are near West Lafayette, Indiana just go try the Purvis Burger across the street from Purdue University.) The truth behind tying sound levels being reduced and ROI together is actually pretty simple.

For this example, I am going to stay fairly high level as we could get into some pretty deep measurements of what exactly could be a cost savings.  If we reduce the sound level being generated by point of use compressed air products that is easiest to do by implementing engineered blow off products as well as reducing the operating pressure. Let’s use this example: A 1/4″ copper tube that is being used as a blow off will give off a noise level of over 100 dBA from 3′ away.  The table below shows that at an 80 psig inlet pressure the same tube will also consume 33 SCFM of compressed air.

By installing a model 1100 1/4″ FNPT Super Air Nozzle on the end of this copper tube, we  reduce the noise level generated by the blow off to 74 dBA. This measurement is at the same 80 psig inlet pressure and from 3′ away, which is well below the OSHA standard for allowable noise level exposure.  This also gives a broader more defined pattern to the air stream which may permit a reduction in compressed air pressure.

The other factor this changes is that the air consumption is reduced by 19 SCFM of compressed air which then results in energy savings.  This ultimately ends in a simple ROI equation where we are simply using the compressed air reduction as the only variable for the return.


By reducing the air consumption of a process that operates 24/7, 250 days a year that equates to  a savings of 6,840,000 SCFM per year and that equates to $1,710.00 USD. This does not account for any reduction in paying for hearing protection that may no longer be needed, or increase in production because the application functions better.

So you see, reducing noise levels in a facility can easily amount to a sizable cost savings in energy going towards compressed air consumption.  If you would like to walk through any potential applications, please contact us. 

Brian Farno
Application Engineer

EXAIR’s Unconditional 30 Day Guarantee = Success!

This week in Cincinnati we hit a record high 79°F. Since less than a week earlier it snowed all afternoon, let’s just say many people around here began to get excited. While I don’t mind a little snow here and there, once February begins to draw to a close I’m ready to bust out the shorts, tank tops and flip flops and bring on some warmer temperatures. It also means I’m right around the corner from opening up the pool. Let’s hope that goes much smoother than last year….


Another benefit to the warmer temperatures, especially here in Cincinnati, is the coming of the baseball season. With the Reds Spring Training also starting this week, optimism is in the air (albeit reserved after the last few years performance).

Unlike baseball where it’s 3 strikes and youuuu’rrrreeee out! EXAIR’s unconditional 30 day guarantee for all stock products allows you the opportunity to test out several different solutions to ensure you get the right product for your application.30dayguarantee

I recently worked with a customer that was interested in switching their current blowoff process with something that would reduce their sound levels but still allow them to complete the job in a similar time frame. The company makes aluminum castings and was using the air gun to remove residual sand leftover in the die after each cycle. Their current air gun was producing sound levels at 107 dBA, well above OSHA’s safe operating range for a full 8 hour shift of work according to OSHA 29 CFR 1910.95(a).

They didn’t want to commit to just one style of air gun, so he purchased a 1210SS-18 (Safety Air Gun w/ ¼ NPT Stainless Steel Nozzle and 18” extension) and a few different additional ¼ NPT nozzles to see which style his operators preferred. After some testing, they concluded that the air gun with an 1122SS 2” Flat Nozzle installed provided them with the best results. Having the added feature of changing out the shim to increase/decrease the force and flow was also welcomed. They’ll be returning the extra nozzles and applying the credit to the purchase of some new 1230SS-18 guns to outfit their other work stations.

Model 1230SS-18 Soft Grip Safety Air Gun

While we do have a highly trained team of Application Engineers ready and available to help you determine the most suitable product, sometimes testing it out at your facility is the best way to ensure a positive result. That is EXACTLY why we give you 30 days to test out any stock product. If for any reason at all you’re unsatisfied with the performance, give us a call and we’ll arrange for a return. Don’t be afraid to swing and miss!

Tyler Daniel
Application Engineer
Twitter: @EXAIR_TD

Reds photo courtesy of Keith via Creative Commons License