Duct Calculation Slide Rule

One of our most popular catalog items! This durable two-sided plastic sizing wheel comes with a complete instruction manual for residential and commercial duct-sizing procedures.


–  Sizes metal ducts, lined metal ducts duct board airways, and wire helix flexible ducts.

–  Converts round shapes to equivalent rectangles.

–  Correlates available pressure with total effective length and friction rate (Manual D sizing calculations).

–  Converts velocity into velocity pressure and vice versa.

–  Corrects for altitude and temperature