User Manual

Fire Safety

Building Technologies 049_Archives_and_Libraries_A6

V10271399_a_en.doc

Fire Safety & Security Products 03.2009

Much higher efficiency can be achieved using pressure relief flaps of more special-

ist design

Hi-Efficiency type vent

Powered vent (driven open and

closed)

Gravity flap pressure relief flap

Some weighted blade vents avail-

able from some suppliers can be

very inefficient

Fig. 25 Pressure relief

Pressure relief flaps can be operated pneumatically:

Fig. 26 Pneumatic operated flap

Advantage: pneumatic flaps have greater free vent area, so vent size is re-

duced

Disadvantages: pneumatic vents cost more and means of testing are required

Gravity operated flaps can also be used and this is the option recommended

by Siemens:

Fig. 27 Gravity operated flap

Advantage: gravity flaps offer the highest reliability

Disadvantages: medium efficiency

Overpressure flap with

Pneumatic activation

Pipe

Overpressure flap

Gravity operated

Overpressure flap