Pressure – Absolute, Gauge, and Units of Both

Compressed air is a common utility used throughout industrial facilities and it has to be measured like any other utility in order to know just how much a facility is using. When dealing with compressed air a common unit of measurement that readily comes up is psi, pound-force per square inch. This unit of measure is one of the most basic units used to measure pressure in the compressed air industry. There are other means to measure this though, so let’s discover the difference.

Again, the pressure is a force distributed over an area, the Earth’s atmosphere has pressure, if it didn’t we would all balloon up like the Violet from Willy Wonka, just without eating some prototype gum causing internal pressure. PSIA is a unit of measure that is relative to a full vacuum. It is pounds per square inch absolute (PSIA). The absolute pressure is calculated as the sum of the gauge pressure plus the atmospheric pressure. If you were to travel into space, the atmospheric pressure would be absolute zero which is actually a vacuum. There is nothing pushing from the outside in so the inside pushes out, hence the ballooning.

The atmospheric pressure on earth is based on sea level. This is 14.7 pounds per square inch absolute pressure. This pressure will change along with the weather and the altitude at which the measurement is taken.

So how do we get to the pressure that is displayed on a pressure gauge?  When shown open to room air, my pressure gauge reads zero psi. Well, that is zero psi gauge, this already has the atmosphere showing. It is not showing the Absolute pressure, it is showing the pressure relative to atmospheric conditions. This is going back to the fact that gauge pressure is the summation of absolute pressure and atmospheric conditions, for sea level on earth that is 14.7 psia. So how do we increase this and get the gauge to read higher levels?

We compress the air the gauge is measuring, whether it is using a screw compressor, dual-stage piston compressor, single-cylinder, or any other type of compressor, it is compressing the ambient, atmospheric air. Some materials do not like being compressed. Air, however, reacts well to being compressed and turns into a form of stored energy that gets used throughout industrial facilities.  By compressing the air, we effectively take the air from atmospheric conditions and squeeze it down into a storage tank or piping where it is stored until it is used. Because the air is being compressed you can fit larger volumes (cubic feet or cubic meters) into a smaller area. This is the stored energy, that air that is compressed always wants to expand back out to ambient conditions. Perhaps this video below will help, it shows the GREAT Julius Sumner Miller explaining atmospheric pressure, lack of it, and when you add to it.

Lastly, no matter where you are, there is a scientific unit that can express atmospheric pressure, compressed air pressure, or even lack of pressure which are vacuum levels. To convert between these scientific units, some math calculations are needed. While the video below is no Julius Sumner Miller, it does a great job walking through many of the units we deal with daily here at EXAIR.

 

If you want to discuss pressures, atmospheric pressure, how fast the air expands from your engineered nozzle to atmospheric, why all the moisture in the air compresses with it, and how to keep it out of your process, contact an application engineer and we will be glad to walk through the applications and explanations with you.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Willy Wonka & the Chocolate Factory – Violet Blows Up Like a Blueberry Scene (7/10) | Movieclips, Movieclips, retrieved from https://youtu.be/8Yqw_f26SvM

2 – Lesson 10 – Atmospheric Pressure – Properties of Gases – Demonstrations in Physics,  Julius Sumner Miller, Retrieved from https://www.youtube.com/watch?v=P3qcAZrNC18

3 – Pressure Units and Pressure Unit Conversion Explained, Chem Academy, retrieve from https://www.youtube.com/watch?v=2rNs0VMiHNw

 

Wet-Dry Vacuum Converts Without Tools in 15 Seconds or Less!

In a recent video, I showcased our newest Industrial Housekeeping product, the EasySwitch Wet-Dry Vac. Throughout my years in metalworking as well as homeownership, I have honestly never used a wet-dry vacuum that is this easy to change operating modes from wet to dry or vice versa. So just how easy is it?

EasySwitch Wet-Dry Vac Mode Change Instructions

When writing out instructions on how to do this it takes a total of five steps for either direction. These five steps can easily be completed in less than 15 seconds and best of all, it is tool-free.

When changing over other wet/dry vacuums, whether it is a traditional electric vacuum like you may have at home or another pneumatic industrial vacuum on the market, the switchover process is cumbersome. There are typically fasteners or retainers that are necessary to hold the filters in place, filters can be poor quality and get damaged easily.  Small parts needed to hold filters in place like springs or retainer nuts can easily be lost, hard to manipulate and take additional time changing from liquid to dry modes or vice-versa. With the EasySwitch, the only fastener is a rubber latch that is attached to the filter hatch cover. This means operators can’t lose parts because they are all attached to the EasySwitch Lid. To convert from a dry vacuum to a wet vacuum the steps are simple.

  1. Turn off the compressed air and unlatch the rubber handle. This makes it possible to complete step two.
  2. Lift the filter hatch lid and let it rest on the hinge stop. This is all designed to be robust enough to easily support the weight of the EasySwitch unit as well as the air hose attached to it.
  3. Lift the filter, whether it is the HEPA rated filter or the standard filter, up and out of the lid.
  4. Close the filter hatch lid onto the edge gasket that stays firmly in place.
  5.  Latch the rubber handle/latch back into place and start processing liquid as needed.

That’s it, it takes less than 15 seconds in the video below (see it at 1:15) and I am pretty sure a speedcuber or cup stacker could do it even faster. Don’t believe me, want to test it out for yourself, we honor a 30-day guarantee on stock products. Get the EasySwitch Wet-Dry Vac in your facility and put it through your own rigorous testing. If it doesn’t perform to your liking, let us know and we will arrange for sending it back. Converting the vacuum from dry to wet isn’t the only thing that is fast, we also ship same day on orders for stock products (hint: all EasySwitch vacuums are stock product) received by 3 PM ET that are shipping within the US. (2 PM ET for orders billing and shipping to Canada.)

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

EXAIR E-Vac Vacuum Generator, How to Pick the Correct One

EXAIR’s compressed air powered E-Vac single stage vacuum generators are a low cost way create vacuum for many operations including- pick and place, clamping, chucking, alignment, lifting, and many others.

The E-Vac provide instantaneous response and are commonly used for pick and place operations.

EXAIR offers the In-Line and Adjustable style of E-Vacs. Both are compact and easy to mount at point of use. With 18 total models available, there is sure to be one that meets any application.  To determine when to use the Adjustable or the In-Line, see this Blog by Russ!

adjustablee-vacfamily
Adjustable E-Vac
In-LineE-VacFamily
In-Line E-Vac

 

 

 

 

 

 

The biggest factor and the first place to start is to determine if the part to be lifted is porous (Example, cardboard) or non-porous (Example, plastic sheet)

  • Porous materials require a low vacuum generator which produces a lower vacuum in exchange for higher vacuum flow which is capable of maintaining a good vacuum level through material that allows air to flow through itself.
  • Non-Porous materials are best suited to use the high vacuum generator which is capable of producing more powerful vacuum for the application.

If you want to see them both in action check this video out! 

E-Vac Video
Click the Video to Watch!

Both the Low Vacuum (for non-porous material) and High Vacuum (for porous material) E-Vacs come in 7 different sizes, ranging from light to very strong vacuum capabilities, to match any application. Special Kits are  available as a way to experiment with an assortment of vacuum cups to determine the best configuration.

e-vac-exair
EXAIR E-Vac Vacuum Generator

If you have questions about vacuum generation and the E-Vac or any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

Send me an email
Find us on the Web 
Like us on Facebook
Twitter: @EXAIR_JS

EXAIR Pneumatic Liquid Vacuums

EXAIR‘s line of Industrial Housekeeping Products consist of liquid and dry vacuums that utilize compressed air to operate. They do not have electric motors which most ‘all purpose’ vacuums rely on.  In industrial settings with harsh conditions and rugged use, EXAIR’s Industrial Housekeeping Products are ideally suited for the everyday wear and tear. 

Reversible Drum Vac with spill recovery kit!
EXAIR liquid type vacuums, like the Reversible Drum Vac, the High Lift Reversible Drum Vac, and the Chip Trappers are reliable, versatile and easy to use. Installing onto an any closed head, 30, 55, or 110 gallon drum creates a high powered vacuum.  It can fill a 55 gallon drum in less than 2 minutes.  Then, with the turn of a knob, the the same pump quickly empties the drum. Useful for refilling coolant sumps, vacuuming floor spills, or transferring contaminated liquids to filtration tanks in minutes.  Flow rate can be controlled with the knob. 
EXAIR Reversible Drum Vacs
The Chip Trapper has an internal filtration system to separate the chips from the coolant, allowing for disposal of the solids, and for pumping of the clean coolant back into the sump.
EXAIR Chip Trapper
When you look at the vacuums, you’ll notice there is not an electrical cord.  Because the EXAIR Industrial Housekeeping Products utilize compressed air for operation, they do not have the same issues with wear, breakdown and failures as electrical type vacuums. There are no moving parts in the vacuum units to wear out or break.  They are maintenance free, just supply clean, dry air, and they will operate for a long time. For the the liquid type systems, there is a built in pressure/vacuum relief device and auto safety shut-off to prevent overfilling.

There are no motors and bearings to wear out and no impellers to clog.  The Chip Vac is 50% quieter than a comparable electric vacuum.  Safety is a top priority, and the use of the unit on wet floors and spills is not an issue when electricity is not involved.

If you would like to talk about Industrial Housekeeping products or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Jordan Shouse
Application Engineer

Send me an email
Find us on the Web 
Like us on Facebook
Twitter: @EXAIR_JS