Vintage Airtemp Ductwork Design Direct Calculator Wheel Chart Slide Rule HVAC For Sale

Add a unique piece of mid-century engineering advertising to your collection with this vintageChrysler Airtemp Ductwork Design Direct Calculator. This circular slide chart (volvelle) allowed HVAC engineers and installers to determine CFM, friction, air velocity (FPM), round duct sizes, and rectangular duct sizes with a single setting.The reverse side features full instructional examples, correction factor charts for pipe roughness, and charts based on historicalASHRAE Guide 1972engineering principles. It is an amazing historical collectible for anyone in the heating and cooling trade or an enthusiast of vintage mathematical slide tools.📐 Measurements & Specifications

• Type:Dual-sided rotatable wheel slide calculator
• Model Number:ATMS79039
• Material:Heavy-duty laminated chart board with metal center rivet

⭐ Condition Report

• Very Good Vintage Condition:The dial rotates smoothly and all printed text, color-coded scales, and mathematical increments are crisp, unfaded, and easy to read.
• Flaws:Features a minor ink annotation ("2-") on the upper back panel from a previous owner (fully visible in pictures). The cardboard edges show minor natural shelf-wear but are completely free of major creases, water damage, or separation.

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