Labconco Rapid Digestors 23080 - Manual (Page 4)

INTRODUCTION
5
General Description
The Rapid Digestors are designed for wet digestions on material such as feeds, grains,
soils, plant tissues, water effluent, organic wastes, and food products. These digestions
are made prior to analysis for nitrogen, calcium, phosphorus, heavy metals, micro-
nutrients, and other materials. The system consists of a control unit, a heating unit with
digestion tubes, and a flask rack for transporting tubes. The flask rack is equipped with
removable side panels providing increased heat transfer to the upper part of the digestion
tubes.
The heating unit consists of individual heaters constructed of ceramic materials providing
uniform and efficient heat transfer to the digestion tubes. The heaters are encased with an
efficient insulating material on four sides and the bottom to prevent heat loss, assuring
low energy consumption and safe casing temperatures. The close tolerance fit between
the inner ceramic tube and the digestion solution provides for shorter digestion times and
uniform digestion temperatures of the sample solution. The heating unit is enclosed in a
chemically etched aluminum casing, assuring easily cleaned surfaces with no paint to
flake off and providing a good appearance throughout the unit’s lifetime.
The control unit is of solid state design and regulates the temperature of the individual
heaters uniformly and accurately. The large temperature set point dial assures accurate
and repeatable temperature settings. The unique light display located on the heating unit
assures accurate temperature setting and allows for visual observation of the Digestor’s
operation.
The digestion tubes are thick-walled, rimmed, and made of borosilicate glass. Each tube
is manufactured to close tolerances to assure efficient and uniform digestions. Digestion
tubes are of the straight non-constricted type of approximately 250-ml capacity or with
construction and an accurate volumetric mark placed at 250-ml volume.
Detailed Operational Function
The Labconco Digestor consists of the digestion unit, the control unit, and accessories
(digestion tubes, flask rack, end plates, and retainer plate). The digestor can
simultaneously handle up to 25 samples, each weighing up to 5 g for solid materials or
approximately 25 ml for liquid samples.
Digestion Unit
The digestion unit contains electrically heated ceramic cores retained in a pan insulated
from the aluminum casing to reduce heat loss and to prevent the metal casing from
becoming hot. The ceramic cores are precision molded to accommodate the digestion
tubes and provide maximum direct contact with the tubes.
The center heating element with the 25-Place, or the rear left with the 4-Place, contains a
RTD platinum sensor that is encased in ceramic to sense the temperature of the digestor
and signals the control unit providing uniform temperature control.