Firma:              Heraeus

Modell:            HB 2448K

Kommentar:   Dokumente engl.

Description

A Class II cabinet consists of a confined work space in which a stable parallel flow (laminar flow) provides protection against cross-contamination between the surroundings, the operator and the product. All operations take place through the work opening. Sub pressure in the work chamber draws room air into the cabinet through the work opening and down through the suction holes in the front of the tabletop. By this the operator is protected against possible emission of harmful substances from the product with which the operator is working.

Technical description

Air movements:

Via the work opening room air is drawn in through the perforated area in the front part of the tabletop. The vertical superfiltered airflow from the main filter separates in the middle so that the air is partly sucked down through the perforated area in the front part of the tabletop and partly sucked down through the perforated area in the rear edge of the work chamber. The total amount of air is mixed below the tabietops.

Prefilter (on HBB only):

Degree of detention 99.99% of particles 0 0.3 pm (DOP-test). (The mixture of air from the work chamber and the work opening is filtered).

Fan:

The air is led to the fan placed in the top of the unit. The fan is of a seif-compensating type and has thus only an insignificant drop in the quantity of air by an increase in backpressure. By means of a built-in transformer the fan can be made to operate with increased power.

The air is then led to the pressure plenum. 25% is exhausted to the room through exhaust filters. 75% is led over the main filter and forms the unidirectional flow in the chamber.

Exhaust filter:

Filter efficiency 99.999% of particles 0 0.3 pm (DOP-test).

Main filter:

Filter efficiency 99.999% of particles 0 0.3 pm (DOP-test).

Alarms:

• Exhaust

The unit has an alarm for too little exhaust air. The supervision takes place via pressure measuring over the exhaust filter - see also the paragraph concerning operation.

• Front window

lf the front window is not in working position, i.e. if it is open or placed above the horizontal green marking, this is indicated by an alarm signal.

Technical data

Property of materials

Subjects                                             Material                                Treatment

Front windows and side windows      Clear polycarbonate

Window frames                                  PVC

Upper part, return duct and                Mild-steel plate                      60 µm polyestercoating pre‑

bottom part                                          ST 1203 DIN 16023              treated to corrosion class 1

Stand                                                   Iron pipe                                60 µm polyestercoating pre

                                                                                                        ­treated to corrosion class 1

Trough, tabletops and suction gate    Stainless steel AISI 304        Polished

Functional parts of the cabinet

( 1) Valves*

( 2) Electrical outlet

( 3) Charcoal filter (4) Main filter

( 5) Centrifugal fan

( 6) Mains connection

( 7) Anti blowback valve*

( 8) Box containing the electrical parts

( 9) Exhaust filter

(10) Lamp cover

(11) Pressostats

(12) Control panel

*(13) Light fittings

*(14)Front window

(15) Work chamber

(16) Cover plate, front**

(17) UV-light*

(18)Trough

(19) Tabletops (tabletop*)

(20) Stand for HB tabletop version

(21) Stand for HB floor model

(22) Prefilter an HBB

(23) Levelling screws.