Coandă Profiles

Here at EXAIR, Coandă is a household name that can be heard on any given day multiple times throughout the day. The Coandă effect is fairly easy to visualize with a ligthweight ball and some high velocity airflow. Take the video below for example. This 2″ Super Air Amplifier on a stand powered at 40 psig at the inlet easily lifts this hollow plastic ball and then suspends the ball due to the Coandă effect.

If you were able to see the airflow, you would see it impacting the surface of the sphere at all different points then following the profile of the sphere until it colides with itself and is forced to separate off the surface. The turbulent flow on the top is creating a downward pressure as well. The science behind this was all found and showcased by Henri Coandă. He showcased this with a propulsion device which used a domed hood with airflow to follow the curvature of the dome then exit off the sharp edge or where the separate air streams began to recombine causing a turbulent / low pressure area depending on the angle.

This stream of air following a surface begins to pull in all surrounding and impacted air molecules from around the stream which is called entrainment. This is a key factor for EXAIR products and one reason the Coandă profiles are a key characteristic to obtaining the peak performance and efficiency out of a compressed air product.

As the high velocity air stream exits the EXAIR model 1100 Super Air Nozzle the ambient air is entrained around the fins and angled surfaces of the nozzle.

Many EXAIR products utilize the Coandă principle to improve their efficiencies and performance. Below you can see the EXAIR product families containing Coandă profiles within their design which increases the ambient air entrainment resulting in an amplified air blowoff.

Super Air Wipes, Super Air Knives, Super Air Nozzles and Super Air Amplifiers use the Coanda principle to become some of the most efficient compressed air blowoff products available.

If you would like to discuss how the Coandă profile and EXAIR Intelligent Compressed Air Products® can help your process, please give us a call.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Compressed Air Pressure Regulators Conserve And Protect

Imagine you’re enjoying a nice shower. A cascade of warm water is soothing your body – and spirit – then, someone starts the dishwasher. Or a load of laundry. Or flushes the toilet. Suddenly, the “soothe” turns to “scald” or “freeze,” depending on whether you’ve been robbed of hot, or cold water.  So, what happened?

What happened is, all of those “loads” on your house’s water supply that can ruin your shower experience are controlled by simple on/off valves…they open to permit a certain amount of water FLOW to pass.  When the dishwasher starts, or someone decides to wash a load of whites, the HOT water from your nice warm shower is diverted, leaving a stream of cold water.  When a toilet flushes, or it’s a load of colors, the COLD water is diverted…and that’s not just unpleasant, but downright painful.  Either way, (in my house anyway,) a teenager is getting read the riot act.

The same phenomenon can apply in a compressed air system, if simple flow control valves are used to throttle the appropriate supply of air to a pneumatic device.  If someone, for example, hooks up an air gun to blow off their tools or parts, the valves on EVERYTHING else will need to be opened up some to keep those devices working the same.  In the case of an air gun like this, it usually happens too quick to make the necessary adjustments (by hand) and you’re probably left with a machine tripped off-line, or a ruined part.

Pressure Regulators can prevent this by keeping (or regulating) their downstream pressure to a set value.  If a load elsewhere in the system is activated, the Pressure Regulator opens up, automatically, to keep its output constant.  When that load is secured, the Pressure Regulator closes back down accordingly.  Either way, no single load affects the operation of any others.

That’s only half the value of the use of Pressure Regulators, though.  The other half is, well…the value.  Just looking at a typical function of many EXAIR Intelligent Compressed Air Products – blow off – they’ll all pretty much accomplish the task if you run them, unrestricted, straight off your header.  That’ll give you a good, strong blast of air flow…and it may be more than what’s required, and a waste of good air.  Pressure Regulators will prevent this by allowing you to “dial in” the supply pressure to whatever it takes to get the job done, and no more.

EXAIR offers a range of Pressure Regulators capable of handling air flow of up to 700 SCFM.

Compressed air isn’t free.  Heck, it isn’t even cheap.  Don’t use any more than you have to, and get the most out of what you do use.  Pressure Regulators are one important step in doing this.  If you’d like to talk about optimizing your use of your compressed air system, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Proper Air Supply Line Size Equals Proper Performance

Pipe_460top
Properly sized piping will allow your compressed air operated equipment to operate efficiently!

On any given day myself and my Application Engineering Brethren here at EXAIR have discussions with customers on air starvation of any given EXAIR Product.  The calls generally start off the same, “The Line Vac is not performing like it should”.  We at EXAIR absolutely want to help you get the most out of our products and we certainly want them to perform to your expectation.  However they must be supplied with clean/dry compressed air at sufficient pressure and volume.

Just the other day I was discussing a performance issue with a customer on a 1″ Line Vac.  The customer thought he needed a larger Line Vac.  I asked the questions regarding the diameter of his Supply Line and if he was using Quick Connect or Push Lock connectors.  He was attempting to feed this Line Vac with 1/4″ Poly Tubing through a elbow Push to Loc fitting.

This 1″ Line Vac was being severely starved for air and therefore not performing as expected.  The 1″ Line Vac require’s 14.7 SCFM @ 80PSI to reach the rated performance of 42″ of water column.

Below is a table for Pipe/Hose sizing from the Line Vac installation manual that you can use as a reference guide.  It is recommended that if using hose for the supply air to go up to the next size over the pipe recommendation.

Chart2

Don’t forget that quick connects and Push Lock fittings are not recommended and could restrict the air flow which will have a negative impact on performance.

If you would like to discuss Line Vacs or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Advantages of Thermal Mass or Thermal Dispersion Flow Measurement

EXAIR’s Digital Flow Meter offers an easy way to measure, monitor and record compressed air consumption. The Digital display shows the current amount of compressed air flow, allowing for tracking to identify costly leaks and/or inefficient air users.

dfm

How exactly does the Digital Flow Meter work?  The unit falls under the category of Thermal Mass or Thermal Dispersion type flow meters.  Below shows the backside of a unit.

IMG_7387

Thermal mass flow meters have the advantage of using a simple method of measuring flow without causing a significant pressure drop. The EXAIR units have (2) probes that are inserted through the pipe wall and into the air flow.  Each of the probes has a resistance temperature detector (RTD.) One of the probes measures the temperature of the air flow.  The other probe is heated to maintain a preset temperature difference from the temperature measured by the first probe.  The faster the air flow, the more heat that is required to keep the second probe at the prescribed temperature.  From Heat Transfer principles, the heat energy input required to maintain the preset temperature is based on the mass velocity of the air.  Using basic physical properties for compressed air, the volumetric rate can be determined (SCFM), and displayed.

It is important to note that the compressed air should be filtered to remove oils, and dried to remove water, as these liquids have different physical properties from air, and will cause erroneous readings.

Advantages

  • Easy to install – No cutting or welding required
  • Summing Remote Display and Data Logger available
  • Sensitive at low flows
  • Rugged, reliable and no moving parts
  • No calibration or set-up required
  • Models from 1/2″ to 4″ schedule 40 iron pipe in stock
  • Short lead time for sizes up to 6″ Schedule 40 iron pipe
  • Available for size 3/4″ to 4″ copper pipe
  • New Wireless Capability

If you have any questions about the Digital Flow Meter 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.

Brian Bergmann
Application Engineer

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Adjustable Air Amplifier Keeps Sensor Cool

Our distributor in China has a customer who visited the United States, while their customer was in the US they saw an EXAIR product installed and wanted to replicate the setup in China. He saw the EXAIR label and reached out to our distributor for help in identifying the part. Taking a quick measurement of the inlet side of the Adjustable Air Amplifier led us to discern it was a Model 6041 1-1/4” Adjustable Air Amplifier.

adjustable air amplifier sensor cooling
EXAIR Model 6041

The product was installed on a baghouse monitoring system. The sensor is used to detect minor leaks within the dust collection system before the leaks create a major problem. The environment in which the sensor was installed results in temperatures that are just above the normal operating temperatures during warmer months and can result in erroneous readings. When this occurs, production is shutdown to prevent a failure of the dust collection system while the filters can be inspected. By installing the Adjustable Air Amplifier to provide a large volume of air and a low level of compressed air consumption, the temperature is able to be maintained within typical operating range for the sensor. This alleviates the need for unnecessary shutdowns (or unnecessary filter replacement), while ensuring that the working environment remains dust-free.

EXAIR’s Adjustable Air Amplifiers are available in both Stainless Steel and Aluminum from sizes ranging from ¾”-4” on the air outlet. The outlet can be ducted as seen in this application, or it can be used as-is. The air gap of the Adjustable Air Amplifier is infinitely adjustable, allowing you to regulate both the air consumption and outlet flow from a “breeze” to a “blast”. In addition to the standard Adjustable Air Amplifiers, we also have a Model 121021 High Temperature Air Amplifier available that is capable of withstanding temperatures as high as 700°F.

Air Amplifiers can be used in a variety of different applications. Not only can they be used in applications requiring cooling, but the air entrainment properties of the amplifier can be used to exhaust smoke as discussed in this application at a foundry. An Adjustable Amplifier can also be used for drying or cleaning parts as well as for conveying light materials.

Regardless of the application, EXAIR has a suitably sized Air Amplifier to fit your needs. If you need an efficient and reliable way to vent, cool, clean, or dry parts give us a call. An Application Engineer would be happy to take a look at your application and provide the best recommendation.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Air Amplifiers – What is an Amplification Ratio?

On Friday my colleague, Russ, blogged about the Super Air Amplifier (see that BLOG here, including a video demo)  In discussing the Air Amplifiers, the topic of amplification was mentioned. Today, I’d like to expand a bit further the amplification aspect of the Air Amplifier performance.

As the name of the device implies, the compressed air used by the Air Amplifier is added to, and thus ‘amplified’, the total output flow of the unit. Depending on the size and type of Air Amplifier, the amplification ratio starts at 12:1 and goes up to 25:1, with the ratio being the output flow to the compressed air usage.

AirAmplifiers.jpg
Super Air Amplifier and Adjustable Air Amplifier

EXAIR offers (2) types- the Super Air Amplifier and the Adjustable Air Amplifier.  The Super Air Amplifier uses a patented shim technology to maintain a precise gap, which controls the compressed air flow and expansion through the unit.  As the expanded air flows along the Coanda profile, a low pressure area is created at the center which induces a high volume flow of surrounding air into the primary air-stream.  The combined flow of primary and surrounding air exhausts from the Air Amplifier in a high volume, high velocity flow.  The larger diameter units have a greater cross sectional area with larger low pressure areas, resulting in greater amplification ratios.

The Below table shows the amplification ratios.

SuperAirAmplifierPerformance

The Adjustable Air Amplifier does not use a shim, but rather has an infinitely adjustable gap, allowing for fine adjustment of performance.  Force and flow is changed by turning the exhaust end to adjust the gap, and is then locked into place. The method of the amplification is the same as for the Super Air Amplifier, and the amplification ratios are similar and shown below.

AdjustableAirAmplifierPerformance

The Super Air Amplifiers and Adjustable Air Amplifiers are ideal for use in applications and processes that require cooling, drying and/or cleaning of parts, or the ventilation of confined areas or weld smoke or the exhausting of tank fumes.

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

Brian Bergmann
Application Engineer

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Consider these Variables When Choosing Compressed Air Pipe Size

Here on the EXAIR blog we discuss pressure drops, correct plumbing, pipe sizing, and friction losses within your piping system from time to time.   We will generally even give recommendations on what size piping to use.  These are the variables that you will want to consider when selecting a piping size that will suit your need and give the ability to expand if needed.

The variables to know for a new piping run are as follows.

  • Flow Rate (SCFM) of demand side (products needing the supplied compressed air)
  • System Pressure (psig) – Safe operating pressure that will account for pressure drops.
  • Minimum Operating Pressure Allowed (psig) – Lowest pressure permitted by any demand side point of use product.
  • Total Length of Piping System (feet)
  • Piping Cost ($)
  • Installation Cost ($)
  • Operational Hours ( hr.)
  • Electical Costs ($/kwh)
  • Project Life (years) – Is there a planned expansion?

An equation can be used to calculate the diameter of pipe required for a known flow rate and allowable pressure drop.   The equation is shown below.

A = (144 x Q x Pa) / (V x 60 x (Pd + Pa)
Where:
A = Cross-Sectional are of the pipe bore. (sq. in.).
Q = Flow rate (cubic ft. / min of free air)
Pa = Prevailing atmospheric absolute pressure (psia)
Pd  = Compressor discharge gauge pressure (psig)
V = Design pipe velocity ( ft/sec)

If all of these variables are not known, there are also reference charts which will eliminate the variables needed to total flow rate required for the system, as well as the total length of the piping. The chart shown below was taken from EXAIR’s Knowledge Base.

Piping
Airflow Through 1/4″ Shed. 40 Pipe

Once the piping size is selected to meet the needs of the system the future potential of expansion should be taken into account and anticipated for.   If no expansion is planned, simply take your length of pipe and start looking at your cost per foot and installation costs.    If expansions are planned and known, consider supplying the equipment now and accounting for it if the additional capital expenditure is acceptable at this point.

The benefits to having properly sized compressed air lines for the entire facility and for the long term expansion goals makes life easier.   When production is increased, or when new machinery is added there is not a need to re-engineer the entire system in order to get enough capacity to that last machine.   If the main compressed air system is undersized then optimal performance for the facility will never be achieved.   By not taking the above variables into consideration or just using what is cheapest is simply setting the system up for failure and inefficiencies.   All of these considerations lead to an optimized compressed air system which leads to a sustainable utility.

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