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Two Lever Disc Valves

Flowseal Two Lever Disc valves are designed and fabricated to meet the requirements of process, gas and industrial plants and are inspected, tested and certified in compliance with API (American Petroleum Institute) Standard 598.

Flowseal Two Lever Disc valves are intended mainly for bubble tight isolation on relatively clean gas systems. They can be designed and manufactured for temperatures up to 600°C and for corrosive conditions.

General Design

Flowseal Two Lever Disc valves can be fabricated to any size, and can round or rectangular. They can be supplied with a variety of different seal arrangements and materials.


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


Housings are designed to be entirely self-supporting in the duct with no external mounting or anchoring required. The flanges are pre-drilled to customer requirements.

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


Damper blades are of single thickness plate construction and can be flat or dished, depending on design pressure. The periphery of the blade is machined to accept the seal material.

Bearings and Bearing Housings?

Bearings shall be maintenance free DU or Vesconite Bushes, under no circumstances will ball or roller bearings be considered due to their potential to brinell and seize under normal damper operating conditions. The bearings shall be located sufficiently removed from any potential heat source to ensure that they are operating within their design temperature rating.

Levers and Links?

The geometry of the levers and links ensures that during the initial stages of opening, the blade lifts of the landing bar flat and parallel to the duct centre line, thus ensuring positive seating and minimal wear to the seals. If required lubrication points for the various bushes can be provided, however, in the interests of reliability, we endeavour to avoid this if possible.


Shafts will always be manufactured in grade 304 stainless steel or better. The shafts are designed to transmit the maximum torque potential of the drive mechanism.

It is imperative that the combined geometry of blade connection, thru bearings, levers and links is such that the full potential forces of the actuator can be accommodated.


Flowseal Two Lever Disc valves can be furnished with electric, pneumatic, hydraulic or manual actuators. The actuators are to be sized to function reliably over the full range of system temperatures and pressures. Actuators may be fitted with positioners, I/P converters, solenoid valves, 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.