Stoplogs are used to shut off water intake screen pits for dewatering. They are normally lifted with equal levels upstream and downstream.

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The stoplog system consists of a grouted metallic wall guide in which slides a fabricated metal door.


The guide is made of two vertical channel guides, a top and a bottom sill set with jack screws and grouted into slots in the civil structure.


The stoplog itself is a fabricated door with a thick back plate, stiffening beams and side members. A keynote seal is fitted on all sides and secured with stainless steel fittings. They apply against the smooth surface of the guides for perfect sealing.


One or more level-equalizing valves are provided (actuated from the deck).


When the stoplog aperture is high, the stoplog is made of a number of sections, set one above the other.


Stoplogs are preferably on-seat but can be either on-seat, off-seat or bi-directional).


There are three types of lifting methods:

  1. Using a crane hooked to the lift chain or the self-engaging lift beam.

  2. When there is a small level differential between front and back levels, mechanical or hydraulic jacks can be provided.

  3. If the gate is to be lifted with a high-level differential between upstream and downstream levels, side rollers and an adequately-sized lifting device are installed. The guides are then of a much heavier gauge.


  • Very economical

  • Very safe (200% safety coefficient)

  • Long-lasting

  • Easy to handle

  • Very low leakage rate (less than 2 l/min/meter of seal)

  • On special request, can be designed for 0.2 l/min/meter of seal (DIN 19569-4 or AWWA C561)


  • 3-side sealing:
    The top of the aperture is higher than the high-water level

  • 4-side sealing:
    The top sill of the aperture is below the high-water level.


Standard widths up to 6 m. Larger stoplogs are available on special order.

Any height can be supplied using multiple elements.

We can custom-design anything to meet your needs.


  • Door:
    Carbon steel is usual, stainless steel on special request

  • Guides and stoplog fittings:
    AISI 304L for fresh-water applications
    AISI 316L, duplex or super-duplex stainless steels for salt-water applications

  • Sacrificial anodes:
    Aluminium alloy


In many countries, regulations or by-laws require that for safety purposes, two sets of stoplogs installed in series with their corresponding guides, are required.  

Check before designing a new plant.