EXAIR Adjustable Air Amplifiers Helps Clear the Smoke

Smoky Foundry
Smoky Foundry

An overseas customer had a problem with their coal blasting furnace. As the workers would open a 1.2 meter by 1.2 meter door to shovel in coal, the foundry would fill with smoke.  This was a hazard and a nuisance for the crew.  They saw articles about how EXAIR Air Amplifiers were used in smaller ovens for exhausting hot flue gases, and they wondered if the EXAIR Air Amplifiers could be used for something much larger.

He sent me an email with some additional details about their furnace system. They had a fan that was mounted in the stack that had a capacity of 50 m^3/min.  This was fed into a filtration collection system to remove the residue byproducts.  The temperature inside the furnace was approximately 450 deg. C.  From this information, I could calculate the required velocity to keep the smoke inside the furnace.

Smoke starting to migrate out of the opening
Smoke starting to migrate out of the opening

In sizing this application, I determined that I could use an equation from Heskestad and Spaulding. This equation was developed to find the minimum velocity required to keep smoke from egressing into corridors during fires.  In this case, we were keeping the smoke from egressing into the foundry.  The formula looks like this:

V = 0.64 * Sqrt(g * H * (T – To)/T)      Equation 1

V – Velocity (m/s)

g – Gravitational acceleration (9.8 m/s^2)

H – Height of Opening (meters)

T – Avg. Fire Temperature (Kelvin)

To – Avg. Space Temperature (Kelvin)

In this equation, we are mainly fighting the forces of the temperature difference from inside the hot furnace area to the outside cooler area.  The outside area was near 40 Deg. C, and this gave me the temperature difference.  In converting these temperatures to the absolute temperature, Kelvin.  I calculated the fire temperature, T, to be 450 Deg. C + 273 = 723 Kelvins; and the space temperature, To, to be 40 Deg. C + 273 = 313 Kelvin.

In placing the given information into Equation 1, the minimum velocity could be found.

V = 0.64 * Sqrt(9.8 m/s^2 * 1.2m * (723K – 313K)/ 723K)

V = 1.65 m/s


If the velocity could be maintained at this mark of 1.65 m/s, then the smoke could not egress into the plant.  They had a stack fan that was flowing 50 m^3/min, or 0.83 m^3/sec.  We can determine the velocity that the stack fan was producing by calculating the flow over an area:

V = Q/A      Equation 2

V – Velocity (m/s)

Q – Flow (m^3/sec)

A – Area (m^2)


With a door opening of 1.2m by 1.2m, or 1.44m^2, the velocity can be calculated by placing the known values into Equation 2:

V = (0.83 m^3/s) / (1.44m^2)

V = 0.58 m/s

Now we can see why they were getting smoke pluming from the coal furnace into their facility. They required a minimum of 1.65 m/s, and the stack fan was only drawing 0.58 m/s.  If we take the difference, we can determine how much additional velocity will be required to keep the smoke within the furnace: 1.65 m/s – 0.58 m/s = 1.07 m/s.


To determine how much air flow would be needed to create a velocity of 1.07 m/s through the door opening, I just had to rearrange Equation 2 to determine the flow, Q.

Q = V * A = 1.07 m/s * 1.44 m^2 = 1.54 m^3/s

To better correlate the flow data, I converted 1.54 m^3/s to 92.4 m^3/min of air flow.

EXAIR's Adjustable Air Amplifier
EXAIR’s Adjustable Air Amplifier

EXAIR Air Amplifiers are designed to have large amplification ratios (the ratio between the amount of ambient air being moved compared to the amount of compressed air used).  This makes them perfect as an efficient air mover.  Being that this was a furnace application, the High Temperature Stainless Steel Adjustable Air Amplifier was required.  This Air Amplifier has a temperature rating of 374 deg. C, and it can be easily mounted at a safe distance to meet this temperature requirement.  The largest unit that we stock is the model 6034, a 4 inch (10cm) Stainless Steel Adjustable Air Amplifier.  It has a 24:1 amplification ratio that can create an outlet flow of 34 m^3/min.  (It would only need 1.42 m^3/min of compressed air at 5.5 bar to create this outlet flow).  For this customer to reach the 92.4 m^3/min to keep the smoke from escaping, he would need to install three units (3 * 34 m^3/min = 102 m^3/min).  He mounted the Stainless Steel Adjustable Air Amplifiers to some extraction wyes in their stack and added solenoids to them.  So, when the crew opened the door to load the coal, the Air Amplifiers would operate to keep the exhaust smoke from filling the room.  The company and operators were very satisfied as it made the environment clear to see and safe to work.

If you have an application where smoke and fumes are a nuisance, you can contact an Application Engineer at EXAIR to see if an Air Amplifier would work in your application.

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

Don’t Cry, EXAIR Air Amplifiers Will Help Remove the Fumes

Bitumen is a black viscous product that is used in asphalt, road surfacing, and roofing materials. Much of this product is moved by either railcars or tractor trailers to other industries.  Some precautions are needed when handling this product as the fumes can irritate the eyes, throat, and nose.

Fumes coming out of hatch below platform
Fumes coming out of hatch below platform


A plant that manufactures bitumen contacted EXAIR to see if we had a product that could improve their existing system. They were using a 6” (15 cm) venturi type air mover that was large and cumbersome.  It had a funnel that extended from the outlet by 4 feet (1.2m), and it weighed over 22 lbs (10 Kg.)  The air consumption of this unit was 81 SCFM (2,294 SLPM) of compressed air at 80 PSIG (5.5 bar).  They had to maneuver this heavy device by hand around an elevated platform.  The platform was designed with two smaller platforms that are positioned over the vehicles that they are filled for transport. One platform extended over a rail for railcars and the other platform extended over a driveway for tankards.  The air mover had to be moved and positioned near the filling areas to capture the fumes.  It was heavy, awkward, and in the way.

Their filling procedure was to place the air mover near the opening of the hatch to remove the irritating fumes away from the operators. The filling pipe was 4 inch (10cm) in diameter, and it was spring assisted for easy positioning.  Depending on the vehicle type, they would open a hatch ranging from 12 inches (30.5cm) to 16 inches (40.6cm) in diameter to fill.  The operator would then position the air mover near the opening, insert the fill pipe, and start filling.  The air mover was turned on to draw the vapor coming out of the hatch.   Because of its weight and size, the air mover had to be positioned on the platform at the edge of the hatch opening.  This was not optimum as some of the fumes could still escape at the farthest point away from the air mover.  Once the railcar or tanker was filled, they would move everything to the opposite platform to fill the next vehicle. Because of the design of the platforms and the size and weight of the air mover, there was a high possibility for personnel to become injured from the re-positioning process.  The customer wanted a more effective and ergonomic solution.

Railcar Filling Area
           Railcar Filling Area

The customer added some additional details about his operation. Because bitumen is a tar-like substance, it sticks and gets on everything, they would place dirty parts in an oven to melt the bitumen off the surfaces.  With this high temperature requirement and the size of the opening of the hatches that had to be covered, I suggested a 4 inch (10cm), Stainless Steel Adjustable Air Amplifier, model 6034.

EXAIR Air Amplifiers, have a large amplification ratio (the ratio between the amount of ambient air being moved compared to the amount of compressed air used).  The suggested model, is set for a 24:1 amplification ratio.  This helps greatly to draw in the fumes and smoke in the surrounding area to increase overall effectiveness and to reduce compressed air consumption.  With the size and weight of the EXAIR Adjustable Air Amplifier being much smaller than their present solution, they could mount it directly onto the side of the spring-assisted pipe used to fill the tankers with the product.  (The weight of the model 6034 is only 9 lbs. (4.1 Kg))  This was a major ergonomic success.  They did not have to worry about their operators hurting themselves moving a big, heavy, air mover, and it allowed the mouth of the Air Amplifier to be positioned right over the opening of the hatch.  This helped to catch all the fumes.  As a bonus, the model 6034 consumes only 50 SCFM (1,416 SLPM) of compressed air at 80 PSIG (5.5 bar).  The Adjustable Air Amplifier allowed for a reduction of 38% in compressed air usage when compared to the old method.  By switching to the EXAIR Air Amplifier, it saved them time, pain, money, and tears from eye irritation.

EXAIR Adjustable Air Amplifier
EXAIR’s Adjustable Air Amplifier

If you have an application where smoke and fumes are a nuisance,  Air Amplifiers are a great way to pack a lot of power into a small space for a variety of blowing and venting applications.

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

Moving Day

This past Saturday morning, some friends and I were invited to a party…a moving party.  Most of us have had them, and most of us have likely hosted them.  In fact, it’s such a popular concept that it has its own bumper sticker:

Yes this is my Truck

Lucky for us (and our backs), there wasn’t anything appreciably heavy – a desk and a couple of dressers were really the worst of it.  As Moving Party Veterans, the relative ease of this move gave us plenty of chances to discuss the pros and cons of various equipment:

Friends’ trucks vs. Rental Truck: if the above bumper sticker doesn’t say enough about this, I’m not sure what will.  Unless you’re moving from your parents’ house to your first apartment, you shouldn’t even consider the former.  It’s not necessarily bad form, however, to ask your friend who shows up with a pickup truck to move, say, your lawn mower in it, so you don’t end up with gas, oil, or grass stains on your mattress.

Dolly vs. Lifting Straps: Appliance dollies are a MUST if you have a washer, dryer, chest freezer, refrigerator, etc., especially if any of those items are going up or down stairs.  They’re not very handy for moving something longer like a piano, though.  For that, nothing beats a good set of lifting straps.  Believe it or not, you don’t have to be a body builder…two able-bodied adults can lift (and carry) quite a bit of weight with them.

Back to the truck…Ramp vs. Lift Gate: The prime consideration here, to me anyway, is the number of heavy objects, and their individual weights.  Yes, a lift gate might be a little slower to run up and down all the time.  You have to leave the truck’s engine running.  There’s only so much you can put on the platform at a time.  But if you have a piano, a gun safe, a giant marble statue (I’ve never had the pleasure of moving one, but here’s an idea: if you can afford one, you can afford to HIRE SOMEONE to move it), then the lift gate is a must, again, to me anyway.

Almost every day at EXAIR, we come across an opportunity to compare and contrast different solutions to an application.  This morning, I had the pleasure of discussing a welding smoke ventilation application with a caller.  He’s currently using an electrically powered blower unit, and, while it’s doing an adequate job, it’s bulky, loud, and if he runs it continuously, it’s also prone to overheating and eventual bearing failure.  He’s testing out a 4” Super Air Amplifier because it addresses each of these concerns:  it’s lightweight and portable, quiet, and, with no moving parts, can run continuously with no ill effects.

Super Air Amplifier

If you have an application that involves moving air, an EXAIR Air Amplifier may be just what you’re looking for.  If you need help moving anything else, I’m busy that day…sorry!

Russ Bowman
Application Engineer
EXAIR Corporation
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
Web: www.exair.com
Blog: http://blog.exair.com/
Twitter: twitter.com/exair_rb
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