TYPICAL DESCRIPTION (it can be modified as per your needs)

• PRINCIPLE
  Emergency closure: Safety gate is used to shut off the full flow of turbine, in case of failure of all other closure systems. It is designed to close by the action of its own weight under any turbine condition including runaway. Emergency closing of the gate takes precedence over all others turbine operations.
  Normal closure: Safety gate can also be used for turbine dewatering like a bulkhead gate, enabling turbine repair or maintenance work.


• Structure
  Generally, Safety gate is made in one section. Each section is a flat box-like structure constituted by one steel panel and horizontal beams spaced so each one is subjected to the same hydrostatic load. Vertical beams located on sides are used to transfer loads to embedded parts (fixed guides). If necessary, some concrete is added as ballast. When there are several sections, they are interconnected by tie rods with swivel ends, thus conferring them an individual freedom of movement.


• Sliding surfaces
  In order to facilitate safety gate operation, it is equipped with sliding surfaces made of UHMW Polyethylene and located on sides.


• Lateral stops
  To avoid any possible jamming, gate is equipped with 4 lateral stops made of UHMW Polyethylene.


• Watertightness
  Watertightness system can be installed on upstream or downstream side of gate depending of site characteristics and customer preferences.
  Generally, watertightness is ensured by Neoprene or rubber seals in the following way:
  • On sides: by "J" bulb seals.
  • On lintel: by center bulb seals (with seal flanges on both sides of bulb).
  • On sill: by a flat type seal comprising appropriate chamfers.
  • Corners: Connections between different seals types are made with the use of molded corners and appropriate cement.


• Frame (fixed guides)
  Fixed guides include:
  • Sliding surfaces made of stainless steel.
  • Sliding surfaces for lateral stops.
  • Seating surfaces made of stainless steel for watertightness on both sides, lintel and sill.
  • Hollow beams containing heating cables (optional).


• Heating system (optional)
  Fixed guides can include two hollow beams along seating surfaces on both sides and into which are inserted heating cables. If required, an adequate heating of guides can be obtained using 500W/m heating elements.


• Small balancing gate (optional)
  In order to limit maneuvering loads at safety gate opening, a small pressure balancing gate can be installed into safety gate structure. By using a special device, bypass opens and closes automatically.
  
  Note: The small balancing gate can be replaced by a bypass piping and valve which will give the same result.


• Handling device (optional)
  We design handling device according to our customer requirements. We can design systems with hydraulic cylinders, electric jacks, winches, hoists, jib crane, etc.
  In all cases, handling device will be designed for two of following three cases:
  • If not equipped with a small balancing gate or bypass: Opening at normal speed under full hydrostatic pressure, but with wicket gates closed. Opening speed is controlled by handling device.
  • If equipped with a small balancing gate or bypass: Opening at normal speed with wicket gates closed (almost no hydrostatic pressure). Opening speed is controlled by handling device. Note: bypass will open first automatically and will eliminate hydrostatic pressure, if any. Control device must wait for removal of hydrostatic pressure before ordering safety gate opening.
  • Closure at normal speed without any hydrostatic pressure and without any water flow (wicket gates closed). Closure speed is controlled by handling device.
  
  For emergency closure, handling device is not involved. Emergency closure is done under full hydraulic pressure and with full water flow (wicket gates opened or partially opened). No system controls closure speed. In that case, when there is more than one safety gate for each turbine, gates closure should be activated simultaneously to avoid hydraulic unbalance or excessive vibrations in turbine. 

ABMS Consultants inc.

Email: ventes@abms.ca