Support

Ducting Specifications & Support

After installation of extraction systems we quality check the job to ensure it is done to the highest standards. However, if you do have any issues, you can contact us to discuss the best way forward.

LEV Testing Information

After installation of each dust extraction system we record details such as airflow velocities, pressure and general performance. We then compile a report to show you the standard performance data for future reference.

Each LEV test is carried out by our experienced staff (we recommend that it is done at least every 14 months). As part of the process we check for any blockages, leakages, or other deficiencies in the installed system. Our team then follow up with a detailed report that outlines any work and offer recommendations that can be carried out to bring the system back up to specification.

The purpose of quick assembly ducting is to be assembled, reassembled, stored and transported easily which is why it cannot be sealed permanently like some other ducting components.

Naturally, because there is no permanent seal there can be leakage involved. This is not unlike other ducting as sometimes even sealed ducting components can leak.

For us to be able to maintain the quick assembly nature of this ducting we have to make sure we are aware of the possibility of leakage with the system.

Below you can see data that outlines the leakage rate per joint of ducts depending on the pressure they are exposed to.

To make an accurate calculation:

  • Count the number of clips (number of pieces) per rise
  • Multiply by the number given beside the corresponding diameter (under the applicable pressure)

When making the above calculation the following assumptions are made:

  • The product is working properly and installed correctly
  • The product is free of dents in the joining ends
  • The gasket is in place
Dia (mm) 3”WG 5”WG 7.5”WG 10”WG 15”WG 20”WG 25”WG 30”WG
100 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
125 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
140 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
160 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
180 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
200 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
250 0.20 0.25 0.30 0.30 0.35 0.50 0.60 0.80
315 0.30 0.30 0.40 0.40 0.40 0.60 0.70 0.90
350 0.30 0.30 0.50 0.70 0.80 0.80 0.90 1.10
400 0.30 0.40 0.60 0.70 1.00 1.10 1.20 1.40
450 0.40 0.40 0.70 0.80 1.10 1.30 1.50 1.70
500 0.40 0.60 0.90 0.90 1.20 1.50 1.70 2.00

Duct Specifications

We ensure minimum of spangle is produced when manufacturing our galvanised sheeting.

Norduct Ltd components are made of galvanised steel sheets, which we produce, by the galvanised continuous process for added durability.

Each sheet complies with lock forming quality (ASTM A-527) and commercial quality (ASTM A-526). And any components made with stainless steel have a 304 2B mill finish, as standard or 2B mill finish should you require.

Rolled Edge – Each material sheet blank is rolled with a fully welded longitudinal seam, and is 1250mm in length. Each end of the duct is then incorporated with a rolled edge and reinforced at every 1250mm.

Flanged – The material sheet blanks for flanged ductwork is 2500mm in length and also incorporate a longitudinal seam. Each side is manufactured with a flat bar flange with the ability to spin.

Ductwork should be supported as follows:

  • 100 Dia – 250 Dia on 7 metre centres.
  • 315 Dia – 900 Dia on 5 metre centres.

Supports should be installed to provide lateral stability to the entire ducting system. Each installation is unique and should be evaluated.

Velocity Requirements for Typical Materials

Conveyed Material Velocity FPM Example
Gases, Smoke, Vapour 1000 – 2000 All Vapours, Gases and Smoke
Fumes 2000 – 2500 Welding
Very Fine Light Dust 2500 – 3000 Cotton Lint, Litho Powder, Wood Flour
Dry Dusts and Powders 3500 – 4000 Light Shavings, Rubber Dust, Soap Dust
Industrial Dust 4000 – 4500 Wet Sawdust, Metal Turnings, Wood Blocks
Heavy or Moist 4500 + Moist Cement Dusts, Quick Lime Dusts

Labour Guidelines

Norduct Ltd provide the information below so you can use it as comparison and for budgetary purposes, it is in no way indicative of the final job installation.

  • A+B = Man hours
  • Rolled edge duct = 10 hours per 50 metres
  • Flanged duct = 15 man hours per 50 metres
  • Straight runs and trunk lines

Machine Connections

  • Machines with 3 or more ports = 3 hours per machine
  • Machines with 1-2 ports = 2 hours per machine

Quick Method = (total number of ports) x 3 hours Y, Y x 2 Ducting system total man-hours.

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