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Introduction to Valves - Only the Basics - Dome Valves -

Dome Valves

Manufacturing of Dome Valves up to 12 “ for Pneumatic conveyor systems & …

Employer: National Iranian Copper Industries Co (Sarcheshmeh copper complex).

These types of valves, produced by reverse engineering method for first time in Iran and similar to the original (west Europe).

A Dome Valve is a quarter-turn rotational motion Valve that uses a Dome-shaped disk to stop or start flow. If the Valve is opened, the Dome rotates to a point where the hole through the Dome is in line with the Valve body inlet and outlet. If the Valve is closed, the Dome is rotated so that the hole is perpendicular to the flow openings of the Valve body and the flow is stopped.

Advantages of using Dome Valves:

  • Quick quarter turn on-off operation
  • Tight sealing with low torque
  • Smaller in size than most other Valves

Disadvantages of Dome Valves:

  • Conventional Dome Valves have poor throttling properties
  • In slurry or other applications, the suspended particles can settle and become trapped in body cavities causing wear, leakage, or Valve failure.

Types of Dome Valves

Dome Valves are basically available in three versions: full port, venturi port and reduced port. The full-port Valve has an internal diameter equal to the inner diameter of the pipe. Venturi and reduced-port versions generally are one pipe size smaller than the line size.

Dome Valves are manufactured in different body configurations and the most common are:

  • Top entry Dome Valves allow access to Valve internals for maintenance by removal of the Valve Bonnet-cover. It is not required to be removed Valve from the pipe system.
  • Split body Dome Valves consists of a two parts, where one part is smaller as the other. The Dome is inserted in the larger body part, and the smaller body part is assembled by a bolted connection.

The Valve ends are available as butt welding, socket welding, flanged, threaded and others.

Materials of Dome and Seats

Dome are usually made of several metallics, while the seats are from soft materials like Teflon®, Neoprene, and combinations of these materials. The use of soft-seat materials imparts excellent sealing ability. The disadvantage of soft-seat materials (elastomeric materials) is, that they are not can be used in high temperatures processes.

For example, fluorinated polymer seats can be used for service temperatures from −200° (and larger) to 230°C and higher, while graphite seats may be used for temperatures from ?° to 500°C and higher.

Dome Valve Stem design

The stem in a Dome Valve is not attached to the Dome. Usually it has a rectangular portion at the Dome, and that fits into a slot cut into the ball. The enlargement permits rotation of the Dome as the Valve is opened or closed.

Dome Valve Bonnet

The Bonnet of a Dome Valve is fastens to the body, which holds the stem assembly and Dome in place. Adjustment of the Bonnet permits compression of the packing, which supplies the stem seal. Packing material for Dome Valve stems is usually Teflon® or Teflon-filled or O-rings instead of packing.

Dome Valves applications

The following are some typical applications of Dome Valves:

  • Air, gaseous, and liquid applications
  • Drains and vents in liquid, gaseous, and other fluid services
  • Steam service
 
 
 

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