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Study on the Performance of Ventiflex Ducting and Couplings

Study on the Performance of Ventiflex Ducting and Couplings. Göran Hansson and Lars Anisdahl (Protan). Ventiflex for mine and tunnel ventilation on a global scale. Objective with this study.

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Study on the Performance of Ventiflex Ducting and Couplings

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  1. Study on the Performance of Ventiflex Ducting and Couplings Göran Hansson and Lars Anisdahl (Protan)

  2. Ventiflex for mine and tunnel ventilation on a global scale

  3. Objective with this study • To assess the friction loss factors, the shock loss factors and the leakage factors for Ventiflex ducting with couplings. • These factors are important design parameters for the whole ventilation system. • Correct assessment of these factors provides a better design basis for Ventiflex systems, and makes it easier to optimise both investment and operating costs for the whole ventilation system.

  4. The Ventiflex coupling system

  5. Couplings Steel-ring Velcro Zip

  6. Design parameters • Friction factor • This tells the magnitude of the friction loss between the flowing air and the inner duct wall. • Shock loss factor • This tells the magnitude of the sudden pressure drops at obstacles (bends, tees, contractions, diffusers, joints, etc.). • Leakage factor, f* • This factor is the average area of leakages given in mm2 (in2) per m2 (ft2) duct wall. • The total pressure at the duct inlet and the air flow rate at the duct outlet are governed by these three factors.

  7. The SIA norm (Swiss standard)

  8. Experimental programme • Three straight ducts of length 400 m and diameter 1200 mm. • One with no couplings. • One with Velcro couplings every 10 m. • One with Zip couplings every 10 m. • One duct length of 2720 m and diameter 1700 mm. • Steel-ring couplings for every 10 m. • Air flow rates and pressures were measured along the ducts. • Based on the measurements, friction factors, shock loss factors and leakage factors were calculated.

  9. From the experiments…

  10. Results: Friction factor (K-factor)

  11. Results: Shock loss factor For comparison: Shock loss factor for a bend or a tee: 0,2 – 1,0

  12. Results: Leakage factor (mm2/m2) No leakages

  13. Results

  14. Duct design using VentiflexCalc Friction factor input Leakage factor input Shock loss factor input

  15. Summary • Friction factors, shock loss factors and leakage factors have been assessed for Ventiflex ducts comprising velcro, zip and steel-ring couplings. • The results confirm that the leakage is zero for correctly installed couplings in a well aligned duct, but it does not mean that there will be no leakages from any installed coupling. • The Ventiflex system easily complies to SIA class S, or better. • However, a Ventiflex system should always be designed according to the particular application.

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