So Many Holes

I remember the book and movie about a young teenager who gets sent to a prison/ work camp that all they do is dig holes. Yeah, there’s a much deeper story line there and that isn’t the point of this blog. The point is, that movie is all I thought of when I encountered this customer’s nozzle solution. Their ejector nozzle on a recycling conveyor was using too much air and was too noisy.

Upon receiving the nozzle to do a free EXAIR Efficiency Lab, we were absolutely amazed at the level of care taken to make something like this. The nozzle was purpose built and definitely got the job done, it also drained their compressed air system at times and made a lot of noise while it did the work. So what did this nozzle look like, now keep in mind, this was not the customer’s design, it was a solution from the machine manufacturer.

For an idea, the customer nozzle was a 3″ overall length, and had a total of 162 holes in it. There were two inlets for 3/8″ push to connect tubing. The holes were very cleanly drilled and we used a discharge through orifice chart to estimate the consumption before testing. Operating pressure were tested at 80 psig inlet pressure.

Discharge through an orifice table.

Our estimations were taken from the table above. We used a pin gauge to determine the hole size and it came close to a 1/32″ diameter. With the table below we selected the 1.34 CFM per hole and used a 0.61 multiplier as the holes appeared to have crisp edges.

Estimation Calculation

Then, we went to our lab and tested. The volumetric flow came out to be measured at 130.71 SCFM. This reassured us that our level of estimation is correct. We then measured the noise level at 95.3 dBA from 3′ away. Lastly, we tested what could replace the nozzle and came up with a 3″ Super Air Knife with a .004″ thick shim installed. To reach this solution we actually tested in a similar setup to the customer’s for functionality as they sent us some of their material.

Now for the savings, since this customer was focused on air savings, that’s what we focused on. The 3″ Super Air Knife w/ .004″ thick shim installed utilizes 5.8 SCFM per inch of knife length when operated at 80 psig inlet pressure. So the consumption looks like below

That’s an astounding amount of air saved for each nozzle that is replaced on this line. The line has 4 nozzles that they want to immediately change out. For a single nozzle, the savings and simple ROI looks like the table below.

Air Savings / Simple ROI

That’s right, they will save 115.02 SCFM per minute of operation. These units operate for seconds at a time so the amount of actual savings is still to be determined after a time study. In videos shared, there was not many seconds out of a minute where one of the four nozzles was not activated. Once the final operation per minute is received we can rework our calculations and see how many hours of line operation it will take to pay back each knife purchase.

If you have any point of use blowoff or part ejection and even have a “nice looking” blowoff in place, don’t hesitate to reach out. These are still very different from our Engineered Solutions. We will help you as much as we can and provide test data, pictures, and even video of testing when possible.

Brian Farno
Application Engineer