Captor Hood Assessment/Testing – Fletchers Excel Spreadsheet

This simple (free to download) Excel spreadsheet ‘crunches’ Fletchers Equations and allows you to do the following, very quickly, simply ….. and accurately:-

  • Determine the Hood Entry Velocity (Face Velocity)required at a Captor Hood (eg welding hood) if you know the hood shape and size, the captor velocity required (eg 0.5m/s for mild steel, 1.0m/s for stainless steel) and the Captor Distance required


  • Calculate the Captor Distance (eg of a welding hood)  if you know the Face Velocity at the Hood, the Hood shape and size and the Captor Velocity required


  • The Captor Velocity which will be achieved at any given Captor Distance if you know the Hood Face Velocity and the hood shape and size

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