Vent Pipe Size Calculator
Vent Pipe from Fixture Units
Calculate vent pipe size based on DFU and length
Formula
Vent size determined by DFU count and developed length per UPC/IPC vent sizing tables
Frequently Asked Questions
What is a plumbing vent?
A plumbing vent allows air into the drain system to maintain proper atmospheric pressure, preventing siphoning of trap seals and allowing waste to flow by gravity.
How do I count fixture units?
Each plumbing fixture has a DFU value: toilet = 3-4 DFU, lavatory = 1 DFU, shower = 2 DFU, kitchen sink = 2 DFU, bathtub = 2 DFU, washing machine = 2 DFU.
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