CSLB C-36 Plumbing ContractorPlanning and EstimatingMedium

A plumbing contractor is reviewing blueprints for a new commercial building. The plans indicate the installation of a 6-inch diameter building sewer serving a large retail space. According to the Uniform Plumbing Code (UPC), what is the maximum permissible drainage fixture unit (DFU) load for this 6-inch building sewer?

  1. A1920 DFUs
  2. B1600 DFUs
  3. C1200 DFUs
  4. D840 DFUs
Show answer & explanation

Correct answer: A. 1920 DFUs

The Uniform Plumbing Code (UPC) specifies maximum DFU loads for various pipe sizes. For a 6-inch building sewer, the maximum permissible load is 1920 DFUs. Exceeding this limit can lead to inadequate drainage and potential backups.

Why the other options are wrong

  • B. This DFU value is too low; it might be applicable to a smaller pipe size or a different section of the drainage system.
  • C. This DFU value is incorrect and falls below the maximum for a 6-inch pipe.
  • D. This DFU value is too low for a 6-inch building sewer.

Building Sewer DFU Capacity

The maximum number of drainage fixture units (DFUs) that a building sewer of a specific size can accommodate, as defined by plumbing codes like the UPC, to ensure proper wastewater flow.

  • DFU values are assigned to plumbing fixtures based on their discharge rate.
  • Building sewer size directly correlates with its DFU capacity.
  • Exceeding capacity can cause drainage issues and code violations.

Memory trick: Don't overload your pipes, know the DFU max to keep the flow right.

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