MFD
Fire & Gas Dampers
Typical Application
Oil & Gas, Marine, Nuclear, Process and General
Removable linkage cover plates are fitted where
Ventilation Systems.
required.
Description
Seals
Tight air shut off is achieved by sprung stainless
AO A60 Deck & Bulkhead Applications
steel grade 316L (1.4404) side seals and welded
top and bottom angle stops.
Casing
Controls for Operation
The damper frame is formed from sheet steel into
Manual Spring Release Latching Mechanism
rigid channel sections that are welded and riveted
Pneumatic Actuator
together. Dampers over 1200 mm wide have welded
Electric Actuator
ver tical mullions and dampers over 1000 mm high
Temperature Sensitive Trigger
have horizontal transoms. Flanges are punched in
For full details see Controls Section page 12.
accordance with the Wozair standard or to specific
client requirements. Where it is difficult to access
Options
the bolt holes behind the control enclosure, welded
Material: Stainless or Galvanised Mild Steel Frames in a
nuts will be provided. Casings are provided with 20 mm
range of thickness from 2 - 10mm
diameter lifting holes as standard.
Case Depth: 200-300mm
Parallel motion linkage
Dampers smaller than 150 mm or required for cir-
Removable Linkage
cular connection are supplied with either 3 mm thick
Continuous blade shafts
transition plates stitch welded to each side or circu-
Bearings: Roller or ball race
lar spigots 50 mm deep. This increases the inser-
Ear th Continuity Bosses
tion depth by either 6 or 100 mm.
Lifting Lugs
Pre-insulated controls enclosure
Blades
Client specific requirements
The blades are double skin aerofoil type from 1.2 mm
Leakage Rates
thick sheet steel and are welded or bolted to 19 mm
The fire and gas damper has been designed to min-
diameter stub shafts. Blade shafts rotate in high
imise leakage with the blades in the closed position.
temperature oil impregnated sintered bronze bear-
To put a precise figure on the leakage rate is not
ings fitted into the damper frame.
practical due to variations in configuration, aspect
ratio, number of blades and perimeter length of
For nuclear applications where the casing penetra-
dampers with equivalent face areas. Extensive test-
tions need to be sealed, lip seal bearings are fitted
ing on single module dampers of size 1000 mm wide
into a bearing housing on the drive side. Blind bear-
x 1000 mm high, has indicated a mean leakage rate
ing bosses are fitted on the non drive side.
of 0.081 m3/sec/m2 at a differential pressure of
2000 Pa. Specific requirements regarding leakage
Linkage
should be discussed with our engineers.
Dampers with multiple blades
are fitted with a linkage to pro-
vide an opposed motion. Robust
blade links are welded to the
drive shafts and connected
together by flat bar and stainless
pins. The linkage arrangement is
contained within the flanges of
the damper frame.
The drive shaft is extended and
fitted with a welded machined
boss for connection to the actu-
ating mechanism. As an option,
par ticularly for nuclear applica-
tions removable linkages can be
specified whereby the blade links
are welded to bosses which are
securely pinned to the shafts.