What is an Air Knife System   Calculate Air Savings   Air Consumption  Best for Application  How Air Knives Work

 
What is an Air Knife System?

Air Knife Systems utilize compressed air for industrial applications that include drying, removing excess oils and liquids, dust blow off, and cooling.

An air knife is effective and efficient.  The laminar (uniform) sheet of air is projected along the entire length of the air knife to provide an air flow that covers the entire surface of the product.  Air Knife Systems from EXAIR have small profiles, are manufactured in various lengths and can be mounted to accommodate many industrial applications involving conveyors and webs, even in tight spaces.  Whether your goal is to remove dust and contaminants, cool hot parts or blow off excess oil, water and liquids, the air knife is also energy efficient.  By entraining high volumes of room air they use less compressed air and less energy than other blow off products.

EXAIR manufactures air knife systems with aluminum and also stainless steel for corrosive environments.  Sizes range from 6 inches to 54 inches.

How to Calculate Air Savings

Super Air Knife Air Consumption*
Pressure Supply Air Consumption per Inch (25mm)
PSIG BAR SCFM SLPM
20 1.4 1.1 31
40 2.8 1.7 48
60 4.1 2.3 65
80 5.5 2.9 82
100 6.9 3.5 99

*with .002" (.05mm) thick shim installed
12" (305mm) Super Air Knife tested

The chart above shows the air consumption of a Super Air Knife per inch of length (25mm) at various pressures. Comparable data is given for holes drilled in pipe.

To Determine Air Consumption for the Drilled Pipe

  1. Determine the size of existing holes and current supply air pressure. From the chart below, find air consumption per hole.
  2. Multiply air consumption per hole times the number of holes to obtain total air consumption.

Holes Drilled In Pipe

Air Consumption Of Drilled Pipe
Air Consumption PSIG 20 40 60 80 100
BAR 1.4 2.8 4.1 5.5 6.9
1/16" (1.59mm) dia. hole SCFM 1.4 2.2 3.0 3.8 4.6
SLPM 40 62 85 108 130
3/32" (2.38mm) dia. hole SCFM 3.5 5.4 7.4 9.4 11.5
SLPM 99 153 209 266 326
1/8" (3.18mm) dia. hole SCFM 6.4 10.2 14 17.5 21.5
SLPM 181 289 396 495 609
3/16" (4.76mm) dia. hole SCFM 14.5 22.9 31 39.5 47.5
SLPM 410 648 877 1118 1344
1/4" (6.35mm) dia. hole SCFM 25 40 54 69 84
SLPM 710 1132 1528 1953 2363

To Determine Air Consumption for the Super Air Knife

  1. From the chart at the top, find the air consumption per inch (25mm) at current pressure and multiply by number of inches required.

Example:

  1. Existing blowoff is 18" (457mm) long pipe with 1/16" (1.6mm) diameter holes on 1/2" (12.7mm) spacing (37 holes), 80 PSIG supply. Air consumption from chart is 3.8 SCFM per hole. Total air consumption is 37 x 3.8 = 140.6 SCFM (3996 SLPM).
  2. Use 18" (457mm) Super Air Knife with standard .002" (.05mm) gap and 80 PSIG supply. Air consumption from chart is 2.9 SCFM per inch. Total air consumption is 18 x 2.9 = 52.2 SCFM (1476 SLPM).
  3. Compressed air saved = 140.6 SCFM - 52.2 SCFM
    = 88.4 SCFM (2520 SLPM).
  4. Most large plants know their air cost. If you don't know your actual cost/1000 SCF, a reasonable average to use is $.25 per 1000 SCF (28,329 SL).
  5. Dollars saved per hour = SCFM saved x cost/1000 SCF x 60 minutes
                 = 88.4 x .25/1000 x 60
                 = $1.33/hour
                 = $53.20 per 40 hour week
                 = $2,766.40 per year savings

 
Which Air Knife is Best For Your Application?
EXAIR manufactures the Super Air Knife™, Standard Air Knife™ and Full-Flow Air Knife™. The table below provides a quick comparison of the three styles.  Super Air Knife (shown left), Standard Air Knife (shown middle), Full-Flow Air Knife (shown right).
 

  Air Knife Comparison

Air Knife Comparison
  Air Consumption Velocity Force per Inch (25mm) Sound Level Amp.
  SCFM SLPM FPM M/S OZS GRAMS dBA RATIO
6" Super Air Knife 17.4 492 11,800 57.9 2.5 71 69 40:1
6" Standard Air Knife 20.4 577 11,000 55.9 2.7 77 83 30:1
6" Full-Flow Air Knife 18.6 526 10,000 50.8 2.3 65 80 30:1

Velocity and force measured at 6" (152mm) from target
Sound level measured at 3' (914mm)
All measurements taken at 80 PSIG (5.5 BAR)

The Super Air Knife provides the best performance with a 40:1 air amplification ratio, making it the most efficient. It is the best choice for all applications. The Super Air Knife has a laminar airstream that is uniform, forceful and quiet. Velocity is the highest of all three air knives. Air consumption is lowest of all three air knives. Compressed air inlets are provided on each end and on the bottom. Multiple Super Air Knives can be mounted "end to end" for longer lengths of uninterrupted airflow.

  • Best choice  for all applications

  • Lowest operating cost
  • Highest efficiency (saves most air)
  • Quietest
  • 40:1 air amplification ratio
  • Compressed air inlets on each end and the bottom
  • Airflow length and overall length are the same
The Standard Air Knife provides good performance with a 30:1 air amplification ratio that is less efficient than the Super Air Knife. It is a good choice when a less expensive alternative is required. The Standard Air Knife has an airflow that is also uniform and forceful. It is louder and uses more compressed air than the Super Air Knife. Compressed air inlets are provided on each end. Overall length is 1" (25mm) longer than the airflow length.
  • Good choice, lower purchase price
  • Highest operating cost of the three
  • Good velocity
  • Higher dBA rating
  • Compressed air inlets on each end
  • Overall length is 1" (25mm) longer than the airflow length
Full-Flow Air Knife provides good performance with a 30:1 air amplification ratio. The Full-Flow Air Knife is the least expensive and is a good choice for tight spaces. Force is less than the other two. Air consumption and sound level falls between that of the Super Air Knife and the Standard Air Knife. Compressed air inlet(s) are provided on the rear. Inlets are available on each end at a small additional charge, however they are not recommended for applications where uniform flow across the length is required.
  • Good choice, lowest purchase price
  • Higher operating cost than the Super Air Knife
  • Smallest size
  • Airflow length and overall length are the same
How Air Knives Work

 


Compressed air flows through the inlet (1) into the plenum chamber of the Super Air Knife. The flow is directed to a precise, slotted orifice. As the primary airflow exits the thin slotted nozzle (2), it follows a flat surface that directs the airflow in a perfectly straight line. This creates a uniform sheet of air across the entire length of the Super Air Knife. Velocity loss is minimized and force is maximized as the room air (3) is entrained into the primary airstream at a ratio of 40:1. The result is a well defined sheet of laminar airflow with hard-hitting force and minimal wind shear.

How the Standard & Full-Flow Air Knife™ Works
Compressed air flows through the inlet (1) into a plenum chamber. It is then throttled through a thin nozzle (2) extending the length of the Standard Air Knife. This primary airstream adheres to the coanda profile (3), which turns it 90° and directs the flow down the face of the unit. The primary stream immediately begins to entrain surrounding air (4), for an amplification ratio of 30:1 at 6" (152mm) away
  Which Air Knife is Best For Your Application?
EXAIR manufactures the Super Air Knife™, Standard Air Knife™ and Full-Flow Air Knife™. The table below provides a quick comparison of the three styles.  Super Air Knife (shown left), Standard Air Knife (shown middle), Full-Flow Air Knife (shown right).
 

Air Knife Comparison

Air Knife Comparison
  Air Consumption Velocity Force per Inch (25mm) Sound Level Amp.
  SCFM SLPM FPM M/S OZS GRAMS dBA RATIO
6" Super Air Knife 17.4 492 11,800 57.9 2.5 71 69 40:1
6" Standard Air Knife 20.4 577 11,000 55.9 2.7 77 83 30:1
6" Full-Flow Air Knife 18.6 526 10,000 50.8 2.3 65 80 30:1

Velocity and force measured at 6" (152mm) from target
Sound level measured at 3' (914mm)
All measurements taken at 80 PSIG (5.5 BAR)

The Super Air Knife provides the best performance with a 40:1 air amplification ratio, making it the most efficient. It is the best choice for all applications. The Super Air Knife has a laminar airstream that is uniform, forceful and quiet. Velocity is the highest of all three air knives. Air consumption is lowest of all three air knives. Compressed air inlets are provided on each end and on the bottom. Multiple Super Air Knives can be mounted "end to end" for longer lengths of uninterrupted airflow.
 
  • Best choice  for all applications
  • Lowest operating cost
  • Highest efficiency (saves most air)
  • Quietest
  • 40:1 air amplification ratio
  • Compressed air inlets on each end and the bottom
  • Airflow length and overall length are the same
Standard Air Knife provides good performance with a 30:1 air amplification ratio that is less efficient than the Super Air Knife. It is a good choice when a less expensive alternative is required. The Standard Air Knife has an airflow that is also uniform and forceful. It is louder and uses more compressed air than the Super Air Knife. Compressed air inlets are provided on each end. Overall length is 1" (25mm) longer than the airflow length.

 
  • Good choice, lower purchase price
  • Highest operating cost of the three
  • Good velocity
  • Higher dBA rating
  • Compressed air inlets on each end
  • Overall length is 1" (25mm) longer than the airflow length
Full-Flow Air Knife provides good performance with a 30:1 air amplification ratio. The Full-Flow Air Knife is the least expensive and is a good choice for tight spaces. Force is less than the other two. Air consumption and sound level falls between that of the Super Air Knife and the Standard Air Knife. Compressed air inlet(s) are provided on the rear. Inlets are available on each end at a small additional charge, however they are not recommended for applications where uniform flow across the length is required.
 
  • Good choice, lowest purchase price
  • Higher operating cost than the Super Air Knife
  • Smallest size
  • Airflow length and overall length are the same