Operating Principle

Operating Principle

The dome component closes beneath the seat (seal) when the seal is relaxed (not inflated), allowing a controlled gap between the seat (seal) and the closing member (dome). Material is allowed to pass through or enter the controlled gap if, due to its characteristics, it is pulled into the gap by the action of the dome component moving to its closed position.

Dome Valve

In the closed position, high pressure air or other gas enters the space between the back of the seal face and the insert ring to cause the seal face to expand onto and around the periphery of the dome component. Material particles are entrapped by the seal against the dome surface, irrespective of particle size or shape. Before opening the valve, the seat is relaxed, and the controlled gap is reestablished before the dome component moves to its open position.

The seal is a loose component clamped into place by a spigot piece and external fasteners holding the top plate assembly to the body. The seal is easily removed for inspection.

Inflatable Seats

Inflatable flexible seats entrap particles that are normally the cause of seat erosion. Particles are induced to move across valve seats under the influence of pressure differentials on either side of the closing member. Entrapping particles within a flexible face during the period of valve closure prevents particle movement and considerably reduces valve seat wear. Inflatable seats allow automatic wear compensation. Inflatable seals are available in the following materials: neoprene, silicone, Viton, food quality neoprene, and Viton, and EPDM.

Dome Valve Seal for Pneumatic Conveying
Dome Valve Seal for Pneumatic Conveying
Dome Valve Seal for Pneumatic Conveying

Exploded View

  1. Top Plate Bolts
  2. Top Plate
  3. Insert Ring
  4. Inflatable Seal
  5. Spigot Piece
  6. Drive Shaft
  7. V-ring
  8. Bearing
  9. Shaft Seal
  10. Seal Retainer
  11. Dome-to-shaft Bolt
  12. Dome
  13. Pivot Shaft
  14. Actuator Mount
  15. Actuator
  16. Proximity Switch
  17. Gasket
  18. Valve Body
Macawber Dome Valve

special performance advantages

The Dome Valve® is used in a wide variety of applications in almost every process. The unique closing and sealing action of the Dome Valve® enables continuous reliable operation where conventional valves fail to perform. Here is why:

abrasive materials

Slurries, bulk powders, granules, lumps or dust-laden gases cause seat erosion and ineffective closure. The inflatable seal provides continuous wear compensation.

pressure differential

Pressure differential also causes accelerated seat wear in conventional seat valves. The inflatable seal provides continuous wear compensation.

high temperature

Thermal expansion prevents consistent valve seat action. The inflatable seal provides compensation throughout the temperature range of 0° to 350°C. Temperatures above this range may be accepted using special valve configurations.

close and seal

The action of the rotating dome within the valve housing allows displacement of material so that a choke-filled Dome Valve® will close and seal through most packed materials.

seal and protection

Seal protection and dome scraper ring remove particles adhering to the dome surface that affect seal performance.

abrasion / temperature / pressure

Dome Valve® can achieve operating reliability in severe applications combining abrasive materials, high temperature and high pressure differential.


A heavy-duty valve designed to perform where other valves cannot. Rated for hundreds of thousands of cycles between inspections in approved applications.

applications in every process worldwide

More than 100,000 Dome Valves® are in operation in almost every country of the world, providing long life and operating reliability where conventional valves have failed.

Dome Valve® Closure and Seal comparison with other valve types

Function:Knife Gate ValveButterfly ValveBall ValveDome Valve
Closing member away from material flowYesNoYesYes
Close without jamming on column of materialNoNoNoYes
Close and seal on column of materialNoNoNoYes
Seal Bubble Tight to:Knife Gate ValveButterfly ValveBall ValveDome Valve
14.5 psi
(1 barg)
100 psi
(7 barg)
623.5 psi
(43 barg)
Combined Pressure and VacuumNoNoMaybeYes