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MTD Series Membrane Check Valve Fine Bubble Diffusers

The MTD Series Membrane Check Valve Fine Bubble Diffuser was developed for use in applications which require fine bubble dispersion in aeration systems which may be cycling on and off. These installations require the integral check valve capabilities found in MTD Series Membrane Diffuser. This design feature prevents the back flow of water when the diffuser is not aerating. Due to its self sealing configuration using a flexible membrane, these types of diffusers are less susceptible to clogging due to solids or biological fouling. Since the membrane expands and contracts when it is aerating and not aerating, there is less opportunity for organism growth on the surface of the diffuser. The membrane diffuser provides more bubble producing orifices on its surface area than comparable diffusers. The MTD Series Membrane Fine Bubble Diffuser is capable of delivering flow ranges up to 12 CFM.
The operating principle of the Membrane Fine Bubble Diffuser is based on raising slightly the air pressure within the membrane tube which opens the diffuser orifices. This horizontal diffuser consists of a rigid cylindrical plenum tube with 1/8” gas distribution slots located inline on the bottom side of the tube. The plenum chamber is covered with a flexible membrane sleeve made of EDPM elastomeric material. This tubular membrane has a tight pattern of extremely small, self-sealing perforations throughout its entire surface except for a solid band running the length of the tube. This band is located over the air diffusion slots of the plenum chamber. When the gas is not flowing through the diffuser, the membrane fits tightly over the tubular plenum chamber. Since the portion of the membrane which is not perforated is located over the distribution slots, it effectively seals any backflow of liquid back into the diffuser when it is not pressurized.

When gas is flowing, the perforated membrane becomes extended, expanding away from the previously sealed air diffusion slots and allowing gas to flow freely beneath the surface of the membrane. The expansion of this membrane sleeve opens the tightly perforated holes very slightly and allows the gas to escape in the form of fine bubbles. The bubbles coming from the diffuser’s surface area create a curtain of gas its entire length. When the flow of gas is stopped the membrane contracts, sealing the distribution slots and closing

the perforations in the membrane. The Membrane Check Valve Diffusers are affixed to the distribution header with a 3/4” NPT stainless steel nipple which allows for easy installation at new and existing plants.
Typical applications for the MTD Series Membrane Check Valve Diffuser include:

  • pre-aeration
  • aeration
  • post-aeration
  • nitrification
  • lagoons
  • aquaculture

The MTD Series Diffuser provides more bubble producing orifices on its surface than comparable diffusers. It delivers flow ranges up to 12 CFM.


MTD-275 3/4" 24" 2 1/2" 1-12

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