Plumbing for Kitchen-waste eliminators

These turn waste into paste and have considerable hygienic advantage since practically all perishable waste can be speedily and effectively disposed of. Exceptions are plastics, aluminium milk-bottle tops, glass and fibrous materials, such as banana skins, which can wrap round the blades of the unit.

Waste-disposal units are operated by an electric motor driving an impeller and shredder blades. These reduce the waste to a paste or slurry which is disposed of as normal sink drainage.

A standard 13A electrical supply is needed, but it is desirable to provide either a pull switch or a wall switch fitted well away from the sink, to avoid operation with wet hands.

To fit a unit, the standard sink outlet requires enlargement. Some sinks can be supplied with the enlarged hole. A standard sink outlet is 38mm; an opening of 90mm is usually needed for eliminator outlets. Enamelled, cast-iron or fireclay sinks cannot be enlarged and have to be replaced.

Hole-cutting saws and, where necessary, recessing equipment can be hired to cut the hole. Usually, sinks are recessed, and all that is necessary is enlargement of the hole.

The hole can, however, usually be cut by a simple metal saw, resembling a junior hacksaw, or provided the blade steel is of sufficiently high-tensile strength, a junior hacksaw can be used.

First, carefully mark the position of the hole, cut a starter hole, with a small-diameter drill, then carefully cut out to the diameter of the outlet. Once cut, trim the opening with a round file.

While the hole should be cut with reasonable accuracy, there is usually tolerance of a few millimetres.

Certain techniques are basic to all units, but the maker’s instructions should be studied and followed carefully.

The existing sink outlet and waste trap must first be disconnected. A new waste-outlet assembly fits into the enlarged hole, then a clamping device connects to a sink bush, which is coated with mastic sealing. A top housing is fitted and lined up for the position of the outlet pipe.

The outlet bend should have a minimum fall of 7½° but a 15° fall is better; this is connected to the trap. A tubular trap is usually specified for waste units since this is shallower, and, consequently, less liable to retain sediment.

On a variety of models, a reversing switch is fitted, which allows any jams to be freed. On some makes of machine, a dummy plate is provided which fits in place of the body of the unit. If a fault develops in the mechanism, and the unit has to be removed, the sink can remain in use by fixing this plate.

Where plastic outlet pipes are used, the body of the unit should be separately earthed.

An ‘o’-ring seal joints the top housing and leaks are unlikely. Slight adjustments can be made to reset seals if there is any seepage of water.

The sink should be firmly fixed at all points to minimize vibration of the unit, which may cause fixings to work loose.

A 38mm waste pipe should be taken into a trapped yard gulley and below the gulley water level, to avoid leaving deposits. If discharge is into a septic tank, this must have a capacity of at least 5,000 litres.

10. November 2011 by admin
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