damper Butterfly valve

Damper butterfly valve is used in the dusty cold air or hot air gas pipeline of ventilation, environmental protection engineering in chemical industry, building materials, power station, glass and other industries. It is used as a gas medium to regulate the flow or cut off the pipeline control device. This type of valve should generally be installed horizontally in the pipeline.

A. Classification

  1. By Structure

(1) Concentric butterfly valve

(2) Double eccentric butterfly valve

(3) Triple eccentric valve

  1. By sealing surface material

(1) Soft sealing butterfly valve

(2) Metal hard seal butterfly valve

  1. By working temperature

(1)High temperature butterfly valve. t>450 °C

(2)Medium temperature butterfly valve. 120°C < t < 450°C

(3)Normal temperature butterfly valve. 40°C < t <120°C

(4)Low temperature butterfly valve. 100°C <t<-40°C

(5)Ultra-low temperature butterfly valve. t<100°C

  1. Real Products classification photos

(1) Concentric soft seal damper butterfly valve – Common application








(2) Concentric metal seal damper butterfly valve – Wind and Dust air ventilation

ventilation damper valve

(3) Double eccentric metal seal damper butterfly valve – Quick open / close

(4) Triple eccentric metal seal damper butterfly valve – Long life span

B. Working principle

Damper butterfly valves can be driven by electric or pneumatic actuator, with signal to automatic control the valve open and close. The actuators rotate the discs freely within 90° to open or close or regulate the flow of the medium.


C.  Leakage Class

(1) Soft sealing butterfly valve: Zero leakage

(2) Metal hard seal concentric butterfly valve: 1% leakage

(3) Metal hard seal double/triple eccentric butterfly valve: Zero leakage


D. Installation

  1. Before installation, you must carefully check whether the valve’s mark and certificate meet the requirements for use. After verification, it should be cleaned. Valves that are not installed should be stored in a dry room. Valves with long storage time should be cleaned regularly, blown dry, and coated with anti-rust oil. A blind plate is applied to both ends of the valve to protect the flange sealing surface.
  2. Install according to the flow direction of the medium; priority is given to horizontal installation.
  3. The connecting bolts of the ventilation butterfly valve and the pipeline should be tightened several times in the diagonal direction. Do not tighten the single piece once to prevent the flange joint from leaking due to uneven force.
  4. When installing the ventilation butterfly valve, it is advisable to use the butterfly plate in the closed position to prevent debris from entering the valve cavity and damaging the sealing surface. When the user wants to test the pressure, the two ends must be clamped with the flange pair and then tested.
  5. When connecting the valve to the pipeline, it is required to use the welded steel flange or the special flange for the ventilation butterfly valve on the pipeline. If a flat welded steel flange is used, the inner hole of the flange must be required to be as large as the inner hole of the washer to ensure an effective sealing surface of the gasket.
  6. The ventilation butterfly valve has adjusted the opening and closing stroke of the control mechanism at the factory. In order to prevent the wrong direction when the power is turned on, the user must manually turn to the first 1/3 of the open position before turning on the power for the first time. And check if the direction of the indicator disc is consistent with the opening direction of the valve.
  7. If the valve is in use, it should be stopped immediately if it is found to be faulty.

electric damper butterfly valve