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Guillotine Dampers

Flowseal Guillotine Dampers are designed and fabricated to meet the requirements of power and industrial plants and comply fully with the requirements of AMCA publication 850-84. They provide effective and reliable isolation in hot, noxious, corrosive and dirty gas flow conditions.

All Flowseal Guillotine Dampers utilize a rugged and heavy duty chain and sprocket drive system to provide a positive drive to the gate in both directions. The reliability of this system has been amply ploved through years of use.

Flowseal Guillotine Dampers are designed so that all parts are field replaceable without removing the frame from the duct. Chain drive maintenance is simple and can be performed whilst the system is on line.

Associated Terms:

  • Spade damper
  • Knife damper
  • Knife Gate Damper
  • Gate Valve
  • Gate Damper
  • Chain Drive Damper
  • Sprocket Driven Damper
  • Tight Isolation Damper
  • Purge Air Sealing Damper
  • Total Isolation Damper
  • High Sealing Efficiency Damper
  • Low Leakage Damper
  • Circular Guillotine Damper
  • Rectangular Guillotine Damper
  • Shut Off Damper

The following styles of guillotine dampers are available:

Type AS single blade Guillotine Dampers.?

Sealing efficiency : 99% of full flow or better.

A single thickness solid plate gate seats on a landing bar on the upstream side of the gate with a series of pins providing the guides on the downstream side. This design provides for effective self cleaning.
Type SS spring seal single blade Guillotine Dampers.?

Sealing efficiency : 99.9% of full flow or better.

A stainless steel leaf spring bears against the upstream side of the gate with the downstream side being guided by a landing bar.
Purge Air Isolation Guillotine Dampers?

Sealing Efficiency: 100%

The damper seal (similar to Type SS) is assisted with the introduction of purge air into a manufactured cavity, at a higher pressure than the system pressure.  This procedure creates an air curtain beyond which the lower pressure cannot travel.

Although this is a Total Isolation damper it cannot be perceived as Man-Safe due to the possibility of purge air supply failure.

General Design

Flowseal guillotine dampers can be fabricated for any duct size, circular or rectangular and can be fitted to a vertical duct or to a horizontal duct with the gate entry from the top or bottom of duct.

The dampers are designed to fulfill specific application requirements and conform to the following minimum specifications.


Materials of construction are selected for their suitability for the conditions of temperature and pressure, and the corrosive and abrasive environment of the system.

Frames are designed to be entirely self-supporting in the duct with no external mounting or anchoring required and are normally fabricated from carbon steel channel sections. The flanges are pre-drilled to customer requirements. On duct openings wider than 2000 mm, one or more pipe blade guides are installed on the downstream side of the gate in the plane of travel.

The frames are designed for the system pressure and temperature as well as construction and transportation loadings.

The gates are fabricated from a single thickness solid plate in Corten A, 3CR12 or other exotic material as may be required. The thickness of the gate is designed so that deflection under full differential pressure, when closed, is less than 1/360th of the duct width. The gate is fully retracted from the duct when in the open position, thus completely eliminating thermal distortion of the gate.

Gate entry seals?

Sealing to atmosphere at the gate port is accomplished by stainless steel spring leaf type seals or pneumatically operated top hat seals. The latter is recommended when the system is under positive pressure.

Chain drive?

The dampers utilize a dual chain drive  using WH78 chain and with sprockets fitted to a drive and an idler shaft. The chain is to be capable of driving the gate with only one chain working and this is to be tested in the works prior to dispatch. The shaft bearings are to be of the maintenance free type.


Flowseal guillotine dampers can be furnished with electric, hydraulic or manual actuators. The actuators are sized to function reliably over the full range of system temperatures and pressures with a minimum factor of safety of two. Actuators may be fitted with manual overrides and fail safe open or fail safe closed devices if required. All actuators are fitted at the factory and fully tested prior to shipment.

Actuators can be fitted to either shaft and on either side of the guillotine