High Vacuum (Non-porous) and Low Vacuum (Porous) E-Vacs: Vacuum Generator Overview

In-Line E-Vac

With the amount of energy in compressed air, EXAIR can manipulate it by design for a variety of applications. One way that we can do this is by creating a vacuum pressure by the Venturi effect. By increasing the velocity of air through a constricted area, a low pressure, or vacuum, is created. Unlike a mechanical vacuum pump, the E-Vac does not have any moving parts or motors to wear. This maintenance free device uses only compressed air to generate a powerful vacuum pressure in a very compact and lightweight design. They can create vacuum levels up to 27” Hg (91 kPa) where complete vacuum is at 29.92” Hg (101.4 kPa). With our single stage systems, we can generate different vacuum levels and flows to create the optimal vacuum generation for your application.

Have you ever placed your hand over the hose of a vacuum? You can feel the maximum amount of vacuum pressure on your hand. The maximum vacuum pressure value is only at the condition of zero air flow. When you remove your hand from the hose, you change the vacuum pressure to a much lower value, but now you have the maximum amount of air flow. Like the E-Vacs, EXAIR has designed the product to either give you the maximum vacuum pressure or the maximum vacuum air flow. EXAIR separates these two vacuum generators as High Vacuum and Low Vacuum.

The high vacuum style is designed for non-porous products like glass, marble, and steel sheets. The low vacuum style is for porous products like cardboard, fabric, and plywood. Both types of vacuum generators are commonly used to pick and place parts, open bags, evacuate molds, and vacuum forming. They are easily adjusted by a regulator and a solenoid valve making the E-Vac very versatile. Even with no moving parts, these vacuum generators are quick to respond with very long cycle rates. The inline design makes them easy to install, so, you can begin using this vacuum product without much setup time. With the single stage design, it eliminates any vacuum fluctuation. I will go through both types of E-Vacs to explain the advantages in using these kinds of vacuum generators for different applications.

The High Vacuum Generator is used for non-porous products in pick and place applications as well as vacuum forming, clamping, and evacuation. This type of generator can create a vacuum pressure up to 27” Hg (91 kPa). In conjunction with the EXAIR vacuum cups, it allows for maximum holding capacity for heavy materials. We offer 7 different sizes ranging from 2 SCFM (65 SLPM) to 31 SCFM (872 SLPM) at 80 PSIG (5.5 Bar). They can be matched to the size and quantity of vacuum cups for increased efficiency as well as for improved cycle rates. If the surface of a rigid sheet is smooth or the application requires a high vacuum pressure, the High Vacuum E-Vac Generator would be the best product to use.

The Low Vacuum Generator is used for porous products as well as more delicate surfaces. This generator has a maximum vacuum pressure of 21” Hg (71 kPa). The design is such to allow for maximum air flow to make up any losses through the material or sealing area. With a regulator, you can control the maximum vacuum level to eliminate dimpling or disfiguring of the surface. Even with fabrics and rough surfaces, the Low Vacuum Generator can still pick up and hold the material. We offer 7 different sizes ranging from 1.5 SCFM (42.5 SLPM) to 17 SCFM (476 SLPM) at 80 PSIG (5.5 Bar). They can also be matched to the size and quantity of vacuum cups as well as to overcome any leakage. If the surface of the product being moved is rough or the surface is very delicate, the Low Vacuum E-Vac Generator would be the best product to use.

EXAIR created a video to show the difference between the E-Vacs as well as a demonstration.

Click Video

For experimentation with the E-Vacs and the vacuum cups, EXAIR offers kits for both types of generators. The standard kit includes four pairs of vacuum cups (matched to the size of the E-Vac), 10 feet (3 m) of poly line, and an assortment of fittings. For the Deluxe kit, it will include the same items in the standard kit, plus an automatic drain filter and a regulator. The E-Vacs are made of a durable 6061 aluminum, but if a different material is required for your application, EXAIR can review this request.

The EXAIR E-Vac offers an efficient, simple, and maintenance free solution to create vacuum. Whether lifting product horizontally or vertically, opening bags, aligning sheets or leak checking, the E-Vac ensures a flexible and reliable way to continuously keep your operation moving. As compared to an electric vacuum pump, these vacuum generators are much smaller, less expensive and much quieter. If you need help in sizing and selecting the correct model, you can contact an Application Engineer at EXAIR.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Even Our Customers Are Sending “Holiday Gifts”

Lately, it certainly has felt like Christmas here at the factory.  Two customers sent in some sample parts  for us to test and provide solutions for their application issues.  Opening the box is like unwrapping a present, what surprise will we find inside?

The first customer currently uses the Line Vac to convey (3) different parts from the floor to a hopper for the assembly process.  (2) of the (3) parts transfer very well, but the third conveys a little too slowly. Having all three parts here at EXAIR allows us to set up testing and determine what the root cause is and recommend a solution that will work equally well for all three parts.

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The second is interested in our vacuum technologies to pick and place some fiber board material products.  Due to the curved surfaces and porous material, getting a good vacuum could be a challenge. By having the sample parts here, we can utilize our Demo Room, and try various E-Vacs with various vacuum cup designs and possibly the Line Vac or Air Amplifiers  to develop a good suction on each item.

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When it isn’t possible to send in samples, we will stand behind the EXAIR Unconditional Guarantee – purchase a stocked catalog item, and you have 30 days to try it your facility, in your process, under your real world conditions.  If after the 30 days you aren’t satisfied, send it back for a full refund – and try something else!

To discuss your application and find out information about sending in material samples to confirm that an EXAIR Intelligent Compressed Air Product can help your process, feel free to contact EXAIR and one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Twitter: @EXAIR_BB

Priming the Pump

Yesterday, I had the opportunity to talk to a customer who was looking to prime a pump to remove a liquid out of an 8 foot deep tank.  He was pulling in the liquid through 1 1/2″ pipe and wanted to prime the pump in 5 seconds.  This was an interesting application for me, because it had some tangible numbers for the design.  In most applications with the E-Vac Vacuum Generators, a customer needs to lift something heavy and they need the job done fast. Those terms are very subjective, and we have to try and prognosticate what vacuum generator will work for the customer. Yesterday was different, the customer had some really defined limits, and I knew what I needed to do in order to satisfy the application.  The engineer in me was very happy with the situation.

Let’s start with the parameters.  He was looking to lift water 8 feet vertically.  8 feet of water corresponds to 7.06 inches of mercury.  The porous E-Vac can generate vacuum up to 21 inches of mercury and the non-porous E-vacs can generate 27 inches of mercury, so all of the E-Vac models can easily draw the liquid up the 8 feet of piping.  This is where most vacuum generator applications stop, but not this one.  If time is not a concern the 800001 will use the least amount of air (1.5 SCFM @ 80 PSIG of inlet) and get the job done, but how long will it take?

This is where you need to use the evacuation charts, from EXAIR.com. Below are two charts from the “Specs” tab for Inline E-Vacs.

E-Vac porous evacuation time

Non-porous Evacuation time

The 1 1/2″ Pipe that is 8 ft. long has volume of around .1 cubic foot.  We need to generate at least a 7.06 inches of mercury, so we will look at the 9 inches of mercury column. It will take the 810002 17.85 seconds to evacuate 1 cubic foot of pipe.  The 800001 will take 14.40 seconds to evacuate the same volume, and  it will use less air.  We will want to use the porous vacuum generator, because we don’t need a very high vacuum to get the job done. If the 800001 can evacuate 1 cubic foot in 14.40 seconds it should be able to evacuate .1 cubic foot in 1.44 seconds which is easily fast enough for the customer.  The math also told us the customer could use up to 27.7 feet of hose to lift up that 8 feet, if he needed to take a non linear path.  If we know that the customer needed to move the fluid more that 27.7 feet, we could move up to the next vacuum generator to get the job done faster, but it was not necessary in this application.

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW

Vacuum Generators: Porous Vs. Non-Porous

I had customer call this week who was using an E-Vac model 800008H, an 8 SCFM Porous Vacuum Generator, to pull a vacuum on four vacuum cups.  He was trying to lift a part with the four vacuum cups placed on a clean metal portion of the part.  Unfortunately he was having a little trouble.  He had to lift the product very slowly because the part could easily be dislodged, if the part was bumped or came to an abrupt stop.

In-LineE-VacFamily
EXAIR’s family of In-Line E-Vac vacuum generators

The problem is a relatively simple one.  The customer choose a porous vacuum generator when he would be better served with a non-porous unit.  The vacuum cups are attaching to a non-porous surface, sheet metal, in a relatively clean environment.  The difference between porous and non-porous units is that  porous units has more vacuum flow available at a low vacuum level, where the non-porous vacuum generators have a higher level of vacuum, but less vacuum flow.  Because of the high vacuum flow, a porous unit is much better for lifting porous materials like cardboard, some particle boards, and fabrics.  The higher vacuum flow of porous vacuum generators helps maintain the vacuum when pulling upon materials which let a constant flow of air through. In the customer’s case, he was lifting a clean sheet of metal, a non-porous material, and needed a higher vacuum level as opposed to a higher vacuum flow. A higher vacuum level [more inches of mercury (Hg) of vacuum] would pull harder upon the metal and hold it tighter.

Let’s look at the customer’s example more closely.  An EXAIR model 800008, porous E Vac, will generate a maximum of 21 inches of mercury (“Hg).  A model 810008, non-porous E Vac, will generate 27  inches of mercury (“Hg).  Let say he was using a 900758 3 1/4” diameter round vacuum cup. If you look at the Vacuum Lift Chart, you see that the 900758 can lift 42.8 lbs. at 21 “HG, but it can lift 55.0 pounds at 27 “HG of mercury.  So in this application the customer can increase their lifting capacity by 28.5% by switching from a non-porous vacuum generator to a porous vacuum generator.

Dave Woerner
Application Engineer
davewoerner@exair.com
@EXAIR_DW