Fouress : Louvre dampers are designed to provided a guaranteed sealing efficiency of 99.9%, or better, on cross-sectional area. They incorporate various flexible metallic sealing systems made of austenitic stainless steel or high nickel alloys. Units can be supplied for both circular and rectangular ducts of all size for temperatures and differential pressures upto, and in excess of 650OC and 2000 mm H2O respectively.

Sealing System

FOURESS Louvre Isolators are provided with the leaf spring type sealing system made up of stainless steel AISI 316 or inconel 625 seals based on end application. The sealing system consists of a thin metal leaf strip.

• Predeflected by a bias spring.
• The seal strip is pressed against the landing surface.
• Either in the frame or on the adjacent blade, forming a flat, 20 mm wide, sealing surface. The operational deflection of the sealing element is 17mm and it can tolerate up to 12mm misalignment without any decrease in sealing efficiency. In the open position the seal is prevented from fluttering by a support plate.
• Against which the seal strip is held by the bias spring.

DUPLEX MUTI LOUVRE Fouress multi louver can also be provided with double row of sealing system on a single blade. To provide
100% tightness in the interspace a peripheral air barrier is created by a small fan ensuring any gas leakage is positively banned.
 

High Temperature Bearings

This specially designed gun metal bearing

• Is self aligning as it is connected to the bracket by a flexible stainless steel diaphragm.
• The large free surface, in combination with the small volume of the diaphragm, and the low temperature conductivity of the material, make the diaphragm a temperature barrier between the bracket and bearing.
• The shaft seal consists of a flat disc, fitting tightly over the shaft, which is pressed against the isolator’s frame by a flexible metallic cone and steel collar. This gives a positive metal to metal seal between the shaft and frame without inhibiting the self alignment capabilities of the bearings or causing excessive friction torque, as can happen with traditional packed glands.

Insulated Frame

A major problem with the traditional multi-louvre design, when installed in internally lined ducts, is distortion caused by the temperature difference between the outside of the duct and the frame, or, if the insulation is continued inside the damper, the landing surface. In the FOURESS design the internal frame can move relative to the external one and still maintain the high sealing efficiency.

A variation of this design is available for an existing duct or chimney which cannot be cut, or have a section removed, and where the units is to be installed piece small.

Linkage System

Simplex Linkage System

LOSS MOTION LINKAGE
With the FOURESS sliding linkage the shafts are connected to each other in such a manner so as to nullify the effects of differential expansion. Thus the risk of a loss in sealing efficiency due to blade rotation is avoided and seizure of the linkage due to expansion of the frame relative of the blades is prevented.

CONTROL AND ISOLATION
FOURESS louver dampers can be supplied with parallel or opposed action blades. The nature of the sealing system that both arrangements give the same high sealing efficiency and no penalty need to be incurred where control and isolation are required in one unit.

ACTUATION
Units can be supplied with electric, pneumatic, hydraulic or manual drive, depending on conditions and size. These may operate the unit from one or both sides.

FOURESS reserves the right to introduce changes in design or specification should we consider them necessary in the interest of improved performance.

The fields of application for FOURESS Isolators extends to many industries and activities, including :

• Cement
• Chemical
• District Heating
• Metal processing
• Nuclear
• Offshore Oil
• Oil Refining
• Petro-Chemicals
• Power Generation
• Refuse incineration
• Steel-making
• Total Energy Systems

Fouress Isolators are being used for the isolation of :

• Precipitators
• SOx Scrubbers
• Boilers
• Air Preheaters
• Reheaters
• Chimneys
• Gas Turbines
• By-pass stacks
• Auxiliary Fans
• Fired Heaters
• Lime Kilns
• Induced Draught Fans
• Pulverised Fuel Mills
• Gas Recirculation Fans
• By-pass stacks
• Auxiliary Fans
• Fired Heaters
• Lime Kilns
• Induced Draught Fans
• Pulverised Fuel Mills
• Gas Recirculation Fans