How to Estimate Leaks and the Impact upon a Compressed Air System

In today’s age where compressed air is often referred to as the 4th utility in an industrial manufacturing facility, leaks throughout the system can add up to serious financial losses. It has been estimated that leaks can waste as much as 20-30 percent of an air compressor output.

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Not only are leaks a source of wasted energy, they can also contribute to other losses such as:

  • Causing a drop in system pressure, resulting in air tools to function less efficiently
  • Increasing the air compressor on/off cycles which shortens the life of it and other components in the system
  • Increased maintenance costs and more planned downtime for the maintenance to be performed
  • A need to install of additional compressors to make up for the inefficiencies caused by leaks

For compressors that have start/stop controls – the below formula can be used to estimate the leakage rate in the system-

Leakage Equation 1

To use the above formula, the compressor is started when there is no demand on the system –  all air operated equipment and devices are turned off.  As the air escapes the system through the leaks, the system pressure will drop and the compressor will turn on and cycle to bring the pressure back up to the operating level. Measurement of the average time (T) of compressor run duration, and time (t) of the system pressure to drop to the set-point can be plugged into the formula and a Leakage Percentage established.

Another method to estimate the leakage rate is shown below-

Leakage Equation 2

The above method requires knowledge of the total system volume, which includes downstream air receivers, air mains, and all piping.  To perform the check, bring the system pressure up the normal operating pressure (P1) and then measure the time (T) it takes for the system to drop to pressure (P2) which is generally around half the operating pressure.  The 1.25 is a correction factor to normal system pressure, since the leakage rate will be less as the system pressure is lowered.

A leakage rate greater than 10% typically shows that there are areas of improvement (leaks that can be identified and repaired)

Any leakage testing and estimating should be preformed regularly, at least each quarter, so as to minimize the effect of any new system leaks. The tests are only one part of a leak detection and repair program. The best way to detect leaks is the use of ultrasonic leak detector (shown below.)  To learn more about the EXAIR model 9061 Ultrasonic Leak Detector, check out this blog that was previously published.

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If you have questions about compressed air systems, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Video Blog: Sanitary Flange Line Vac

The below video reviews the Sanitary Flange Line Vac, the newest type from the EXAIR family of Line Vacs.

 

Sanitary Line Vac Family
EXAIR offers the Sanitary Line Vacs in diameters from 1-1/2″ (19mm) to 3″ (38mm), all in stock!

 

PowerPoint Sanitary Flanged Line Vacs file

If you have questions about the Sanitary Line Vac, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Controlling Temperature and Flow in a Vortex Tube

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A few weeks ago, we looked at the Vortex Tube and provided a general overview of the device (see that blog here.)  In a nutshell – a Vortex Tube uses an ordinary supply of compressed air as a power source, creating two streams of air, one hot and one cold – resulting in a low cost, reliable, maintenance free source of cold air for spot cooling solutions.

One of the features of the Vortex Tube is that the temperature of the cold air and the cold air flow rate is changeable. The cold air flow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet.

Vortex Tube Hot Valve Adjustment
Hot Valve Adjustment for a Vortex Tube

Opening the valve (turning it counterclockwise) reduces the cold air flow rate and the lowers the cold air temperature.  Closing the valve (turning it clockwise) increases the cold air flow and raises the cold air temperature.

VT Adjustment Table

As with anything, there is a trade off – to get higher a cold air flow rate, a moderate cold air temperature is achieved, and to get a very cold air temperature, a moderate air flow rate is achieved.

An important term to know and understand is Cold Fraction, which is the percentage of the compressed air used by the Vortex Tube that is discharged through the Cold End.  In most applications, a Cold Fraction of 80% produces a combination of cold flow rate and and cold air temperature that results in the maximum refrigeration or cooling output form a Vortex Tube.

For most industrial applications – such as process cooling, part cooling, and chamber cooling, maximum refrigeration is best and the 32XX series of Vortex Tubes are preferred.  For those applications where ‘cryogenic’ cooling is needed, such as cooling lab samples, or circuit testing, the 34XX series of Vortex Tube is best.

To set a Vortex Tube to a specific temperature, simply insert a thermometer into the cold air exhaust and adjust the hot valve.  Maximum refrigeration, at 80% Cold Fraction, is achieved when the cold air temperature drop is 50°F (28°C) from the incoming compressed air temperature. See the video posted here for measuring and lowering and the cold air temperature.

For those cases when you may be unsure of the required cold air flow rate and cold air temperature to provide the needed cooling in an application, we would recommend an EXAIR Cooling Kit.  The Cooling Kit contains a Vortex Tube, Cold Air Muffler, Air Line Filter, and a set of Generators that will allow for experimentation of the full range of air flows and temperatures possible.

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EXAIR Vortex Tube Cooling Kit

To discuss your application and how a Vortex Tube or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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EXAIR’s Case Study Library

Did you know that you can find 35+ published Case Studies regarding many of the EXAIR products and how customers were able to save on compressed air and increase safety simply by installing and using one of our Intelligent Compressed Air Products?  Case studies provide real world results and highlight any dollar savings, production increases, quality improvements, safety improvements, and/or problems solved. The Case Studies are a valuable tool which can help determine success within your plant or aid in convincing a manager to implement an air savings project. With registration, they can be found under the Knowledge Base tab on the main page of the website, or simply click here.

Once on the Case Study page, you can search and sort by Product type or Application. Reading through the Case Studies of the type of product(s) of interest can provide valuable information on the compressed air savings and safety improvements that others have achieved, and that you might be able to realize as well.

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The Case Studies involve measurable data from actual processes and offer learnings that can relate to applications and processes that are similar to those in your facility.

  • Each Case Study begins with the Application Goal – what was it that was to be achieved by the installation and use of the EXAIR product.
  • Then, we review the Before EXAIR condition –  what was the problem, and what was being used initially.
  • Next, we show the After EXAIR process – this details the EXAIR product(s) that were implemented, and how it was able to improve the process.
  • Finally, the Summary section – this shows the cost savings attained, from less compressed air usage, faster operation rates, lower quality defects, reduced sound levels, and so forth that have been achieved and documented.

We invite you to read, download, and share the Case Studies, and use them as another tool available to you to learn about EXAIR products and how they can improve your processes.

We are always interested in learning about the compressed air savings and increased safety that have been realized by the use of an EXAIR product, and if you could share that information with us and have it result in a Case Study, we would love to talk to you and discuss how we can work together.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Vortex Tube Overview

VT_air2

A Vortex Tube uses an ordinary supply of compressed air as a power source, creating two streams of air, one hot and one cold – resulting in a low cost, reliable, maintenance free source of cold air for spot cooling solutions.

The EXAIR Vortex tubes are made of stainless steel, which provides resistance to wear, corrosion and oxidation – ensuring years of reliable, maintenance free operation

How_A_Vortex_Tube_Works

The cold air flow and temperature are easily controlled by adjusting the slotted valve in the hot air outlet.  Opening the valve reduces the cold air flow and the cold air temperature.  Closing the valve increases the cold air flow and and the cold air temperature.

EXAIR Vortex Tubes come in three sizes. Within each size, a number of flow rates, which are dictated by a small internal generator, are available. Selection of the appropriate Vortex Tube can be achieved either by knowing the BTU/hr (Kcal/hr) requirements or the desired flow and temperature requirements. Selection is then based on the specification table (BTU/hr or Kcal/hr is known) or the performance tables (flow and temperature is known.)

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Vortex Tube Specification Tables

 

Cold Fraction
Vortex Tube Performance Tables

The performance of a Vortex Tube is reduced with back pressure on the cold air exhaust. Low back pressures up to 2 PSIG ( 0.1 Bar) will not change performance and a 5 PSIG (0.3 Bar) will change the temperature drop by approximately 5°F (2.8°C)

The use of clean air is essential, and filtration of 25 microns or less is recommended.  EXAIR offers filters with 5 micron elements and properly sized for flow.

A Vortex Tube provides a temperature drop to the incoming supply air.  High inlet temperatures will result in a corresponding rise in the cold air temperature.

EXAIR offers mufflers for both the hot and cold air discharge.  If the cold air is ducted, muffling may not be required.

For best performance, operation at 80 to 110 PSIG (5.5 to 7.6 Bar) of supply pressure is recommended. The Vortex Tubes have a maximum pressure rating of 250 PSIG (17.2 Bar) and a minimum requirement of 20 PSIG (1.4 Bar)

To discuss your application and how a Vortex Tube or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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Heat Transfer – 3 Types

When you have two objects and they are of different temperatures, we know from experience that the hotter object will warm up the cooler one, or conversely, the colder object will cool down the hotter one.  We see this everyday, such as ice cooling a drink, or a fan cooling a person on a hot day.

The Second Law of Thermodynamics says that heat (energy) transfers from an object of a higher temperature to an object of a lower temperature. The higher temperature object has atoms with higher energy levels and they will move toward the lower energy atoms in order to establish an equilibrium. This movement of heat and energy is called heat transfer. There are three common types of heat transfer.13580963114_f222b3cdd9_z

Heat Transfer by Conduction

When two materials are in direct contact, heat transfers by means of conduction. The atoms of higher energy vibrate against the adjacent atoms of lower energy, which transfers energy to the lower energy atoms, cooling the hotter object and warming the cooler object. Fluids and gases are less heat conductive than solids (metals are the best heat conductors) because there are larger distances between atoms.  Solids have atoms that are closer together.

Heat Transfer by Convection

Convection describes heat transfer between a surface and a liquid or gas in motion. The faster the fluid or gas travels, the more convective heat transfer that occurs. There are two types of convection:  natural convection and forced convection. In natural convection, the motion of the fluid results from the hot atoms in the fluid moving upwards and the cooler atoms in the air flowing down to replace it, with the fluid moving under the influence of gravity. Example, a radiator puts out warm air from the top, drawing in cool air through the bottom. In forced convection, the fluid, air or a liquid, is forced to travel over the surface by a fan or pump or some other external source. Larger amounts of heat transfer are possible utilizing forced convection.

Heat Transfer by Radiation

Radiation refers to the transfer of heat through empty space. This form of heat transfer does not require a material or even air to be between the two objects; radiation heat transfer works inside of and through a vacuum, such as space. Example, the radiation energy from the sun travels through the great distance through the vacuum of space until the transfer of heat warms the Earth.

EXAIR‘s engineered compressed air products are used every day to force air over hot surfaces to cool, as well as dry and/or blow off hot materials. Let us help you to understand and solve your heat transfer situations.

To discuss your application and how an EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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The picture “Energy Transfer – Heat” by Siyavula Education is licensed under CC BY 2.0

Special Cabinet Cooler Options – High Temperature, Non-Hazardous Purge and Type 316 Stainless Steel

Recent blog discussions about the EXAIR Cabinet Cooler Systems have covered many topics including correctly sizing one, the NEMA ratings, and how-they-work.  In this blog I will review three special options that are available for the most extreme environmental conditions- high temperatures, dirty environments, and harsh or corrosive areas.

High Temperature – For enclosures that reside in high temperature ambient conditions such as near furnaces, boilers, or ovens, EXAIR offers a High Temp version, with special internal components designed to withstand the elevated temperatures.  Cabinets near sources of high heat certainly need to be kept cool, and the EXAIR High Temperature Cabinet Cooler is specially suited to for use in these locations.

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High Temperature Dual Cabinet Cooler System

Non-Hazardous Purge (NHP) – Cabinet Cooler Systems with this feature provide a continuous positive purge within the enclosure to prevent contaminants from entering through small holes or conduits.  Especially suited for dirty and dusty environments, the NHP Cabinet Cooler Systems provide a slight positive pressure inside the enclosure. This is done by passing 1 SCFM (28 SLPM) of air through the cooler when the the solenoid is in the closed position. When the thermostat reaches the set-point temperature and energizes the solenoid, the full line pressure of air is delivered to the Cabinet Cooler providing the full cooling capability, and still keeping the positive pressure.  When the internal temperature cools to the set-point, the solenoid closes and the system returns to the 1 SCFM (28 SLPM) of air flow condition.

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Non-Hazardous Purge Cabinet Cooler for Dirty, Dusty Environments

Type 316 Stainless Steel NEMA 4X Cabinet Coolers – For enclosures that are in food service, pharmaceutical, harsh, and/or corrosive environments, and any application where 316 stainless steel is preferred, the Cabinet Coolers are available in the Type 316 stainless material. The systems are UL Listed for wash down environments, ensuring the enclosure electrical contents remain cool and dry under any condition. Noted applications include on ocean going ships, power plants, medical device manufacturing facilities, and bakeries.

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Type 316 Stainless Steel NEMA 4X Cabinet Cooler System

Please note that the High Temperature, Non-Hazardous Purge and Type 316 Stainless Steel Cabinet Coolers are each available from stock!  No waiting for these special models.

To discuss your application and how a Cabinet Cooler System or any EXAIR Intelligent Compressed Air Product can improve your process, feel free to contact EXAIR, myself, or one of our other Application Engineers. We can help you determine the best solution!

Brian Bergmann
Application Engineer

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