E-Vacs and the Curiosity Around Porosity

At a quick glance, EXAIR’s E-Vacs appear to be very simple, but like all of our products they have passed the scrutiny with intelligent engineering design and testing to be able to perform some of the most strategic applications imaginable. Our E-Vacs are used in many applications from picking up and placing a small plastic bag, to lifting large sheets of stone. Another application is the “Pluck-N-Chuck“, where we pick up an object from one area and drop it in another.

As you can imagine, the E-Vacs used to pick up a 1/4 oz bag, as opposed to an 800 pound sheet good, are very different in size and capacity. We have all the data necessary to size your system, and can give recommendations on the number and size of the units you will need to accomplish your task. Most of that is simple math. How heavy vs how much lift you can get and so on. But there are a few other aspects that many times get overlooked. We need to figure in the shape, and porosity of your product.

We have different types of vacuum cups that are best suited for different surfaces. Does your surface have ridges and bumps? Is it curved or round? Are you lifting it from the top, or the side? Most of these factors can be solved with the type of vacuum cup you choose. In the video below, you will see a curved surface using the Bellow cups. These offer more surface ares (levels of the cup) to make contact with and lift the product.

Cardboard – Photo by OpenClipart Vectors and licensed by Pixabay
Glass – Photo by dflamini and licensed by Pixabay

The other portion that is a huge factor in choosing the proper E-Vac, is the porosity of the item being lifted. If the surface will absorb air and or liquid, it is considered porous. Examples of porous surfaces are cardboard, concrete, paper, wood, carpet and many others. Non-porous items will not allow air or water in. Think plastics, hard surfaces, glass, plastics, finished woods, and much more.

Porosity is so important that we make 2 types of E-Vacs, based upon this one factor. Our Low-Vacuum generators are designed to lift these porous surfaces. What may appear to be backwards thinking, the generators that lift the porous materials actually pull less vacuum than the non-porous. 21″ of Hg vs 27″ of Hg. However, the non-porous unit pulls more volume of air through the cup, 18.5 SCFM vs 15.8 SCFM. The lower vacuum, and more air flow, allows the E-Vac to overcome the leakage and lift the porous items.

In the example below, you will see the porous paper towels vs the non-porous paper towels that are still wrapped in plastic. Each E-Vac Generator is identical to each other, except the one on the right is the porous E-Vac, they both even have the same bellow cup for the curved paper towel roll. You will see that they both have an identical amount of supply air as they share the same source of air. The paper towels are identical, other than one is wrapped in plastic (non-porous). Take a look:

As you see the Low Vacuum higher Air Flow E-Vac had no issue picking up both products. But the non-porous, High Vacuum E-Vac could not pick up the porous roll.

I trust this was a good example of the importance of choosing the right engineered product for your specific application. If you have any questions, please reach out to us. We will be happy to help sort the details for your application.

Thank you for stopping by,

Brian Wages

Application Engineer

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