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

The power of the 2” High Power Flat Super Air Nozzle in a blow-off application

A stamping company contacted me for help in their ejection blow-off system.  Their operation consisted of a punch press that would form two 8” X 8” triangles from a square piece of metal.  The operation of the punch press was to cut the square piece diagonally at the same time forming the outside edges of the triangle.  At the end of each stroke cycle, the formed parts would then be blown off the die with compressed air.  The blow-off system consisted of two pipes, one that was a ¾” NPT pipe and the other that was a ½” NPT pipe.  They both had the ends of a long nipple flattened to concentrate the air flow.  EXAIR has reduced air use, saved money, and lowered noise levels for many similar applications by replacing open blow-off devices with our engineered air nozzles.

In giving me more details about their operation, the system had a timing sequence that controlled an actuator. When the cycle was complete, the actuator, located below the tabletop of the punch press, would open and send compressed air through both pipes.  The positions of the blow-off pipes were designed to eject one part off the side of the die and the other part off the front of the die into a collection chute.  (Reference the picture below)  They were having issues when their blow-off system wasn’t consistently able to eject the 1 lb. part completely off the die.  In manually having to remove the parts, it would cause an unsafe environment as well as a slowdown in operations.  They found that EXAIR manufactures Intelligent Compressed Air Products and wondered if we could help.

Blow-off Setup
Blow-off Setup

With a lack of restriction at the end of the pipe, the air pressure will drop quickly as it travels through a relatively long length of pipe. The actuator, which was more than 3 feet away from the end of the pipes, had a line pressure of 90 psig (maximum that they could supply).  By the time the compressed air reached the ejection site, the pressure was much lower; thus, not quite removing the part from the die.  An example that I like to use is a garden hose attached to a spigot outside your house.  As you open the spigot, water will flow out of the hose at a slow velocity; not very strong, that is the same as air through an open pipe.  When you place your thumb partially over the end of a garden hose you restrict the flow and increase velocity. Engineered nozzles from EXAIR work the same way.  They restrict the flow at the nozzle, increasing the pressure for a more effective velocity and blow-off force.  Neal Raker wrote a great blog for EXAIR referencing how the nozzles work; called “What’s in a Nozzle?”

HP1125 2" High Power Flat Super Air Nozzle
HP1125 2″ High Power Flat Super Air Nozzle

I recommended the model HP1125, 2” High Power Flat Super Air Nozzle. It has a 2” wide air stream to allow more contact against the side of the triangle edge.  It has a force of 2.2 lbs. at 80 psig which is more than enough to eject the 1 lb. formed part.  As an added benefit, it only has a noise level of 83 dBA which is magnitudes more quiet than the open pipe.  Also in using the engineered nozzles, they were able to use much less compressed air in their blow-off, saving them over $1,000/year.  If you find that your open pipe blow-off is too loud, not effective, or uses way too much compressed air, you should contact an Application Engineer to see which engineered nozzle would best suit your application.

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

Where Did All The C Clamps Go?

Over the past week I visited a local company here in Cincinnati that utilized a decent number of flat plastic air nozzles on their production lines.   This style nozzle had been used for many years but were the reason their engineering department contacted EXAIR.   The nozzles they had in place were used in many different applications from ejecting bad parts, holding up box flaps, and even positioning product correctly on the production line.   Every nozzle was tied to a regulator somewhere on the machine and all of the regulators were tuned to different pressures.

The customer was experiencing, at certain points during the day, a pressure drop throughout the entire system that would cause packaging lines to shut down due to low air pressure faults. The customer called EXAIR because they determined the plastic nozzles were using too much compressed air and were also a constant maintenance problem. Primarily, they wanted to see if we had a solution to lower compressed air while still achieving the desired production results.

Being local we were able to visit the customer and after discussing the applications we set out through the manufacturing area to discover if we could offer solutions for the problematic areas. We got about 10′ away from a casing machine and I heard a loud hiss of compressed air.   This was even with my foam ear plugs in.  Once we reached the edge of the machine I was quickly able to trace the sound down to a plastic flat nozzle that had been mounted to the machine, broken and held back in place by a large C clamp like seen below.

IMG_5777.JPG

As we went through the rest of this production line and the rest of the packaging facility, it was clear the customer had settled on using flat plastic nozzles throughout the plant. Generally we see this because the nozzles are cheap – when you forget to consider operating and maintenance costs. This was not the only broken nozzle being held in place by a clamp and it is also the not the only one that was using more compressed air than necessary.

After finishing the tour and performing some tests here in our lab I recommended that they utilize our 1″ Flat Super Air Nozzle with a .005″ thick shim installed.   By installing the 1″ Flat Super Air Nozzle they are going to be able to mount the metal nozzles with minimal modification to their existing setup as well as lower air consumption and noise level. The metal construction makes them more durable and long lasting in an industrial environment. These nozzles will not break when an operator bumps it and the maintenance department will be able to reclaim all the C clamps that are distributed throughout the facility.

Once we have final numbers on how many nozzles have been replaced and what pressures each nozzle is operated at we will provide the customer the air consumption savings as well as the noise level reduction that they are seeing throughout the plant.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Change Your Vacuum System at a Moments Notice

In my video from two weeks ago, I showed the operation and adjustment of the adjustable vacuum generator.  The video was short and simple for the viewer, but during the brainstorming of the video, I thought of a variety of topics I would like to cover.  Today, I thought I would expound on some of the ideas and benefits of why you would adjust the vacuum level on a vacuum generator.

AdjustableE-VacFamily_jpg

As Russ mentioned in his blog this week, there are a variety of uses for vacuum generators.  The “textbook” application for vacuum generators is in conjunction with vacuum cups for pick and place applications.  For this application, you typically want to use a vacuum generator that is designed for the material that you are lifting.  For instance, a porous vacuum generator should be used when lifting  cardboard, fabric, paper, or foam (materials that let air flow through).  If you’re lifting metal, solid plastic, wax covered cardboard, or anything else that will stop the flow of air and have a smooth surface, a non-porous vacuum generator should be used.  You can use a porous generator on a non-porous surface, but you will be using more compressed air than you would use with a non-porous generator.

Now that we know when to use a non-porous generator and a porous generator what do you do if you production line or warehouse is changing the products it is moving.  Say that you want to be able to lift stainless steel products in the morning, but in the afternoon you are looking to lift the cardboard boxes containing the (now packaged) product.  The adjustable vacuum generator is much more efficient to adjust than changing all of the vacuum generators or having a different lifting rig for each application.

Alternatively, if you are using a vacuum generator to draw a vacuum on a vessel and that vacuum needs to be specifically controlled.  Say the material can’t withstand a vacuum above 10 inches of mercury or you need to reach a minimum vacuum level in .5 seconds to evacuate a vessel.  The Adjustable E-vac will allow you to use the minimum amount of compressed air to get the job done.

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW