Overview: Adjustable E-Vac Vacuum Generators and Vacuum Cups

Adjustable E-Vac

When it comes to vacuum systems, EXAIR manufactures a very compact and reliable product line called the E-Vac Vacuum Generators.  As a simple vacuum pump, you only need to connect to a compressed air source.  It uses a venturi design to generate high vacuum levels very efficiently.  Since they do not require motors, they are low cost with a wide range of vacuum flows and pressures.  EXAIR offers three different types, the High Vacuum Generators for non-porous objects, the Low Vacuum Generators for porous objects, and the Adjustable E-Vac Vacuum Generators.  In this blog, I will cover the Adjustable E-Vac Vacuum Generators and the variety of suction cups that we provide.

The Adjustable E-Vac gives flexibility to your vacuum system to change the vacuum levels.  The simplicity in the design makes it a great tool for lifting, clamping, chucking, and pick-and-place.  The design also allows for adjustability.  By loosening a lock nut, you can turn the body to reach different vacuum levels.  So, they can be used to move both porous and non-porous materials.  We offer four different sizes with vacuum flows ranging from 5.8 SCFM (164.2 SLPM) to 81 SCFM (2293.6 SLPM).  With the Adjustable E-Vac, you can change the vacuum pressure to go as high as 25” Hg (85 KPa).  Ideal for dialing in the correct vacuum for delicate materials or controlled clamping.

Adjustable E-Vac: How it works

The Adjustable E-Vacs can be packaged in a variety of ways.  The kits help to experiment with different vacuum cups to help determine the best fit for your application.  EXAIR offers two types of kits, the standard kit and the deluxe kit.  The Adjustable E-Vac Kit would include the E-Vac, an assortment of four vacuum cups that are matched to the performance of the Adjustable E-Vac, an assortment of vacuum fittings and 10 feet (3 meters) of vacuum tubing.  The Adjustable E-Vac Deluxe Kit has the items in the standard kit above plus an Automatic Drain Filter and Pressure Regulator with gage.  With both individual units and kits, you can add a muffler to help reduce the noise even more by adding an “M” to the end of the model number.

EXAIR also offers a variety of suction cups to attach to a variety of objects.  We have the small round, the large round, the oval, and the bellows suction cups.  With the different designs, you can pick up a wide range of materials, both porous and non-porous items.  The vinyl material resists wear and distortion for many repetitive cycles.  Here is a better description of each cup below:

Round Cups

Round:  EXAIR has a small and large round style.  This gives us a range of surface areas that we can target to help maximize lift.  They can come either with cleats for heavier lifting and stability or without cleats.  They work great with flat smooth surfaces for horizontal and vertical lifting.

Oval Cup

Oval:  The vacuum is defined by a skinny long area.  EXAIR offers four different sizes.  If you have tight spaces or selectable targets like opening a bag at the top, then the oval shape will work.  They can also handle flat rigid sheets like wood, glass, cardboard, and composites.

Bellows Cup

Bellows:  These suction cups are best suited for uneven or contoured surfaces.  The convolutions around the diameter allow for the cup to collapse and “wrap” around uneven surfaces.  The internal volume is larger than the other cups, so the release and attach times will be extended.  But, for odd surface formations, they can come in very handy.

To combine the Adjustable E-Vac with the Vacuum Cups, how can we determine which ones to use in your application?  Here is some information that we will have to know before getting started.  I like to use anagrams for memory recall, and here is a list that I like to call MOST:

  1. Material
  2. Orientation
  3. Size/weight
  4. Time

Material will tell us if the object is porous or non-porous.  Porous objects are items like cardboard, fabric, cement, etc.  The material can have a rough surface or pores that will allow air to pass through or around the cup.  The Adjustable E-Vac can have the vacuum pressure altered to pick up the material without damaging the surface.   Non-porous objects are items like glass, metal sheets, and plastic.  They have a smooth texture on the surface.  These materials should use the highest vacuum pressure of 25” Hg (85 KPa) to hold the most weight.

Orientation will help us to calculate a safety factor.  EXAIR’s motto has always been safety.  This is important because we want to make sure that the object is secure during movement.  We just need to know if the object is being picked up horizontally only, or if the object is being picked up vertically or rotated in a vertical position.  Then we can apply a safety factor to handle the weight in any orientation.

Size/Weight is simple.  The size is the area that we can pick up the object.  In some instances, we may only have a small target area while in other applications, we will have an entire sheet.  The type of Vacuum Cups is selected by this target area.  The weight will determine the number of Vacuum Cups and Adjustable E-Vacs required to pick up large objects safely.

Time is for applications with cycle rates.  If the job requires a set time to support and release in a known time frame, then we can determine the correct Adjustable E-Vac This can be used for leak checking, clamping, and automatic packaging.

The Adjustable E-Vac Generators are simple, flexible, and very reliable.  As a vacuum pump, they are very compact because they do not use any motors which can wear out.  If you contact an Application Engineer at EXAIR with MOST, we will be able to get the most from your vacuum system.

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

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