Automatic Diaphragm Level Control Valves

Self actuated pilot operated control valves are in use worldwide and have become the natural choice for level control applications. However, problems such as perceived complexity, tampering and vulnerability to particles in the water, as well as the cost of large bore valves, have led to the development of a novel range of self actuated level/flow control valves which solve a lot of these problems.


The FDS automatic diaphragm valve (DV) was developed in South Africa by Fluid Dynamic Systems in the mid-1970s. Since then numerous DVs have been installed in Southern Africa and now also the rest of the continent.

The DV will automatically maintain a discharge flow with varying upstream heads. It can also maintain a constant upstream water level with varying downstream discharges. It is a low head, high flow rate valve which ranges in size from 150NB to 1600NB and can control discharges down to as low a head difference as 0,5m. It is designed to handle dirty water and does not use any screens on the control piping.

This valve can be fabricated for either a top entry downward facing DV or for a bottom upward facing DV and finds applications in numerous installations including:

  • Canal flow regulation, mainly for raw and dirty water in irrigation schemes.
  • Discharges into holding or balancing dams in irrigation schemes where the DV controls the inflow, as well as closes off when the dam is full.
  • Flow control into raw water and wastewater treatment works.
  • Reservoir top and bottom inlet where the DV is situated inside the reservoir for protection against vandalism.
  • Bottom outlets from dams. (DV have very good energy dissipation characteristics.)
  • Actuation and control DVs for Amanziflow automatic spillway scour and canal gates.

The DVs are designed to meet site specific conditions and design criteria. They are totally automated to control flow without maintenance required and are therefore ideally suited for remote sites and African conditions.

The DV float control valve can be fitted with an electric actuator connected by telemetry to a control room, situated kilometers away, to provide remote adjustments to the flow.

The DV is very versatile in application and compliments the Ultra ACV range of control valves. More information and drawings here.

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