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Global Leaders in Flexible Couplings, Drainage & Plumbing Systems


Penstock Back Open webPenstocks are used to control liquid flow, in applications that include water, waste water and sewage treatment plants, drainage infrastructure, waterways, power plants, industrial effluent plants and hydro power.

Operators can control water flow through the penstock by fully opening the gate, fully closing it or partly opening it, as the situation requires. They can play an important role in flood control situations.

There is a range of operating gear options available, from spindle extension sets through to fully automated systems. Non-rising spindles are fitted as standard, although rising spindles are also available.


  • Manufactured to BS7775
  • Much lighter in weight than penstocks of other materials, with no cranes required during installation
  • Gasket forms watertight seal between penstock and wall, so that grouting is not necessary
  • The above benefits can reduce installation time from an average of three days with traditional penstocks, down to around three hours on average
  • Wedgeless design reduces complexity, lowering the possibility of issues in service
  • Self-lubricating door nut requires no maintenance, provided the penstock is operated once a year
  • Materials used are corrosion resistant, offering a long life and low maintenance costs
  • A range of operating gear options available, including spindle extension sets, rising spindles and fully automated systems
  • Stainless steel penstocks also available on request
  • Our penstocks are supplied in accordance with ISO 9001:2008 requirements.

Construction Materials

Component Standard Materials Options
Frame Grade 304 stainless steel (1.4301) Grade 316 stainless steel (1.4401)
Slide gate HMPE 500 Grade 316 stainless steel (1.4401)
Backing plate HDPE 300  
Reinforcements Grade 304 stainless steel (1.4301) Grade 316 stainless steel (1.4401)
Non-rising spindle

Grade 304 stainless steel (1.4301), TR25 x 7.5

Spindle bearing PTFE  
Door nut POM (self lubricating) Bronze
Bolts & nuts Stainless steel A4  
Seal NBR  


Optional features, also available:

  • Non-standard sizes
  • Electric, hydraulic or pneumatic operating systems
  • Rising spindle
  • Wedge construction
  • Accessories, including hand wheels, guide brackets, tee keys and caps

To download the Flexseal Penstock Datasheet please click here.

To download the Flexseal Water Management brochure please click here.