CSLB C-36 Plumbing ContractorPlanning and EstimatingMedium
A plumbing contractor is reviewing plans for a new commercial kitchen. The plans specify a floor drain that will receive discharge from a large commercial steamer, which operates continuously and produces significant hot water discharge. To prevent thermal shock and potential damage to the drainage system, what type of fixture should be included before the floor drain to cool the discharge?
- AAn indirect waste receptor
- BA backwater valve
- CA tempering tank
- DA grease interceptor
Show answer & explanationAnswer & explanation
Correct answer: C. A tempering tank
A tempering tank is used to cool high-temperature discharge from fixtures like commercial steamers before it enters the drainage system, preventing damage to plastic pipes, seals, and the sewer system from thermal shock.
Why the other options are wrong
- A. An indirect waste receptor is an open fixture that receives discharge from equipment, but doesn't specifically cool it.
- B. A backwater valve prevents sewage from backing up into the building, unrelated to temperature.
- D. A grease interceptor separates grease from wastewater, unrelated to temperature.
Tempering Tank
A plumbing fixture designed to cool high-temperature wastewater discharge from commercial equipment (e.g., steamers, diswashers) before it enters the building's drainage system.
- Prevents thermal shock to drainage pipes (especially plastic), seals, and the public sewer system.
- Typically uses a cold water inlet to mix with and cool the hot discharge.
- Required by plumbing codes for discharge exceeding a certain temperature (e.g., 140°F or 150°F).
- Often includes an overflow and vent.
Memory trick: Hot steam's flow, tempering tanks make it slow and low.