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In this episode of Mastering Wisconsin Plumbing, we walk step-by-step through how to interpolate Water Supply Fixture Units (WSFUs) into Gallons Per Minute (GPM) using Table 3 of SPS 382.40 from the Wisconsin Plumbing Code. You’ll learn how to read the columns for flushometer vs. flush tank fixtures, how to handle fractional WSFU values, and how to apply the interpolation formula to get accurate GPM results.

This guide is perfect for plumbing apprentices, journeymen, master plumbers, inspectors, and anyone studying the Wisconsin Plumbing Code. Whether you’re preparing for your plumbing exam, teaching apprentices, or looking to refresh your skills, this lesson makes interpolation simple and practical.

📘 Topics covered:

• What WSFU and GPM mean in plumbing
• How to use SPS 382.40 Table 3
• Step-by-step interpolation example
• Real-world application for flushometer and flush tank fixtures

🔧 Strengthen your code knowledge and bring confidence to every job!

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