Page 589 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 9 Sanitation systems

stack and forms a backflow loop as shown in Figure 9.62. The vent pipe must
discharge in accordance with BS EN 12050–1 for faecal lifting plants to above
roof level, to avoid foul smells from entering the dwelling.

p Figure 9.62 A waste water lifter

Sink waste disposal units

These units are installed in kitchen sinks and need a pre-made hole, 89–90 mm
in diameter, in the sink to fit the unit. A standard 40 mm trap will fit on the
outlet of the waste disposal unit.

These are installed under sinks to dispose of waste food and cooking products
from a kitchen, and then discharge into the drainage system. The cutting or
grinding blades can deal with a large range of food matter, including bones. The
process turns anything in the unit into a paste solution, then water flushes this
into the drain via a 40 mm waste outlet. The electric motor that turns the rotor
where the blades are attached is located at the base of the unit. A sink housing
one of these units requires a larger waste outlet than normal, approximately
89 mm, and manufacturers usually supply this on the cutlery bowl. The motor
on the unit should be connected to an electrical supply via the correctly
sized fused spur outlet, with a fuse appropriately sized in relation to the load
(typically 10 amp).

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