User Manual

e1851a

Siemens Building Technologies

Cerberus Division

01.2002

Fig. 14 and Fig. 15 show clean room variations with unidirectional airflow directed vertical-

ly downwards and Fig. 16 with unidirectional airflow directed horizontally (laminar flow).

Another variant with so-called filter-fan units is gaining increasing importance. With this

system, the filters can be exchanged more easily and safely. The overpressure in the clean

room ensures that falling dust particles cannot reach the clean room. The concept with filter

fan units offers better and greater flexibility.

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Legend:

1 Pre-treated outside air

2 Extract air

3 Circulated air

Fan

Filter

Fig. 17 Section through clean room with vertical flow and filter fan units

Normally, according to the principle of unidirectional airflow, air speeds of 0.3 to 0.5 m/s are

required to ensure stable flow control. For that reason there are considerable quantities of

air to be re-circulated here (approx. 600 air changes/hour).