Plumbing Fixtures, Sanitary Ware and Appliances
Plumbing Fixtures, Sanitary Ware and Appliances tests fixture selection, installation heights, trap seals, flushing and water efficiency. The exam asks why a fixture smells, why a trap gurgles, or which fixture suits a public toilet.
Core fixture facts
- WC: wash-down or siphon ic; dual-flush cisterns commonly deliver 3/6 L; floor-mounted or wall-hung with a carrier.
- Wash basin: 800–850 mm rim height; bottle or P-trap below; 32–40 mm waste.
- Kitchen sink: 900 mm typical; 40 mm waste; grease trap in commercial kitchens.
- Urinal: flush valve or sensor; 50 mm trap; bowl height according to user group.
- Floor trap: 50 mm water seal; grating removable for cleaning.
- Trap seal: at least 50 mm for most fixtures; maintain by use and venting. A P-trap is preferred to an S-trap because it resists self-siphonage.
Worked example
A toilet block has 4 WCs at 3 fixture units each and 4 urinals at 1 fixture unit each. Total = (4 × 3) + (4 × 1) = 16 fixture units. Use this load with the pipe-sizing table and add the flush-valve demand if the urinals use flush valves. Do not size the branch on pipe diameter alone.
Traps
Forgetting the trap seal, omitting a vent, installing a basin waste without a trap, or mixing fixture-unit values costs marks. Also check accessibility for maintenance; a concealed trap needs an access panel.