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Air Leak in Dust Collection and Ventilation Systems

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holes in an elbow by coal dust abrasion


In a dust collecting system, the duct, fan, and dust collector are all susceptible to abrasion from dust particles, high-velocity gas flow, and chemical corrosion.

The elbows are most vulnerable to abrasions.

Air leakage around an access-door or hopper and loose flange isn’t uncommon either.

Many times, these holes on ductwork, fans, and dust collectors are not repaired and left alone, so they grow bigger and bigger and air leakage becomes an even worse problem.

Airvate did some calculations to estimate sucked-in air volume through a hole based on available data regarding the hole’s area and gauge pressure inside of a duct or dust collector. The calculations are listed in the table below. Along with the sucked-in air volume, moisture volume is also listed in the last column for an 8-hour shift assuming that the sucked-in air is saturated with water vapor, like what would happen on a rainy day.

4 hole-sizes are selected: 3 round holes of sizes 7/16”, ½”, and 1” in diameter, and 1 rectangular hole of size 2” by 3”.

 From the calculation results, it's very clear that when the hole-size increases, the sucked-in air volume and moisture volume in an 8-hour shift increase as well. The same happens when the inside negative pressure increases.

This moisture will hurt the performance of a baghouse.

So, when a hole or damaged seal is seen, please repair it as soon as possible, and at the same time figure out what caused the problem and fix  it to prevent further damage to the performance of the system.

In fact, when we have to drill holes on ducts for measurements, preventing moisture is the reason, we always plug the holes with rubber plugs.

AirvateLLC offers the following services to our customers:

·        Dust collection system and industrial ventilation system testing and balancing

·        Dye test for bag leak

·        Technical services: field survey and dust collection system evaluation

·        New system start-up

·        Dust sample analysis

·        Dust collector selection and sizing: baghouse, wet scrubber, cyclone, settling chamber, drop-out box, etc.

If your dust collecting system or ventilation system needs service, feel free to email us at info@airvate.com  to get the help you need.

Hole area (ft2)

/dimension (inch)

Inside pressure

(inch H2Og)

Air volume bleeding-in

(ACFM @70F & 1atm)

Moisture sucked-in

in 8-hour (Gallon)

(Saturated Air @70F & 1atm)

0.001044 / 7/16” ɸ

-2

3.6

0.24

 

-4

5.0

0.33

 

-6

6.2

0.41

 

-8

7.0

0.47

 

0.001364 / 1/2” ɸ

-2

4.6

0.31

 

-4

6.6

0.44

 

-6

8.0

0.53

 

-8

9.3

0.62

 

0.005454 / 1” ɸ

-2

18.5

1.23

 

-4

26.2

1.74

 

-6

32.1

2.13

 

-8

37.1

2.47

 

0.04167 / (2”x3”)

(approx.  8 (1” ɸ) holes)

(approx.  31 (1/2” ɸ) holes)

(approx.  40 (7/16” ɸ) holes)

-2

142

9.41

-4

200

13.3

-6

245

16.3

-8

283

18.8

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