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 NEW Product Offering – Pressure Sensing Digital Flowmeters

Six Steps to Optimizing Your Compressed Air System

The first step to optimizing compressed air systems within an industrial facility is to get a known baseline. To do so, utilizing a digital flowmeter is an ideal solution that will easily install onto a hard pipe that will give live readouts of the compressed air usage for the line it is installed on.  There is also an additional feature that we offer on the Digital Flowmeters that can help further the understanding of the compressed air demands within a facility.

The Pressure Sensing Digital Flowmeters are available from 2″ Sched. 40 Iron Pipe up to 8″ Sched. 40 Iron Pipe.  As well as 2″ to 4″ Copper pipe.  These will read out and with the additional Data Logger or Wireless Capability options record the information. When coupled with the wireless capability an alarm can be set for pressure drops that give live updates on the system as well as permits data review to see trends throughout the day of the system.

EXAIR Digital Flowmeters w/ Wireless Capabilities

Generating a pressure and consumption profile of a system can help to pinpoint energy wasters such as timer-based drains that are dumping every hour versus level based drains that only open when needed. A scenario similar to this was the cause of an entire production line shut down nearly every day of the week for a local facility until they installed flowmeters and were able to narrow the demand location down to a filter baghouse with a faulty control for the cleaning cycle.

If you would like to discuss the best digital flowmeter for your system and to better understand the benefits of pressure sensing, please contact us.

Brian Farno
Application Engineer


Bottling Line Can Run Efficiently by Taking a Few Simple Steps

I recently visited a local customer who bottles a liquid drink.  They do two different sizes, single serve and gallon bottles.  The main issues they were having is the gallon bottles were not dry enough after they come out of a cooling / rinse tunnel.  They currently had three different blow off devices in place outside of this cooling tunnel.  The cooling tunnel had hundreds of spray nozzles to both rinse and cool the gallons of liquid.

On the exit of the tunnel there was a blower driven air knife that was being powered by a high maintenance motor that was also sucking in non filtered air to blow the moisture off thee gallon jugs.  The blower was not producing high velocity air and the knife position could not be adjusted for maximum effectiveness due to the hard piping from the blower.

The bottles come out of the blower and go from a 60″ wide conveyor to a 24″ wide conveyor in about five feet of travel. The bottles are then funneled down even further into a single file line and then sped up and sent through two 90 degree bends to try and knock any residual water off them before going into the casing machine.

There were no other blow offs on the gallon line because they were concerned with their compressed air use.  The other two blow offs they had in place were on the single serve bottling line. On that line there were two points that had six separate clusters of a metal flat nozzle that was approximately 1″ wide and were all pointed at a different point of the cap to try and eliminate some moisture that would get trapped under the lip.

The single serve bottles would come out spaced approximately six inches apart but the nozzles were blowing continuously.  This was a very large waste of compressed air.  They could have very easily installed an EXAIR EFC on these supply lines to cut their usage by more than 50% of their current demand.   They then went past an open pipe blow off to help dry the final labeling point.   This was also on continuously which was another opportunity for air savings.

I recommended installing two Electronic Flow Control (EFC) units and replacing their existing nozzles and open pipe with the EXAIR model 1126 1″ Flat Super Air Nozzle outfitted with swivels to allow them to be positioned properly to reach under the bottle cap. Proper positioning, in many cases, increases the effectiveness of the nozzles and can get the job done with fewer nozzles installed. In this application I am confident we can get that bottle cap area blown off with only 2 nozzles.

By eliminating excessive nozzles and cycling compressed air on and off only as needed, the customer saves compressed air. I estimated it was enough compressed air to install a 24″ Deluxe Super Air Knife Kit to blow down on top of the gallon containers, which is the primary reason they asked me to visit in the first place. This will not only give them the 24″ Super Air Knife, but it will also include the crucial EFC and a filter separator to clean the compressed air and a pressure regulator to adjust the pressure down to the minimum necessary for success. All of these factors contribute to optimizing compressed air and using it effectively within anyone’s plant:

  • Eliminate open pipes and ineffective blow offs
  • Turn off compressed air whenever possible
  • Keep it clean to reduce wear and maintenance
  • Adjust the pressure to a minimum level for success

This is just one location in the entire facility where implementing the Electronic Flow Control and EXAIR engineered nozzles will help the customer to optimize their compressed air use.

If you would like to learn more or have questions on any of the EXAIR products mentioned in this blog, feel free to contact us.

Brian Farno
Application Engineer