With over 30 years of experience working alongside the industry’s leading players, PXL SEALS has developed a complete range of seals tailored to the main hydroelectric applications.

The solutions offered include:

• Pelton, Francis, Kaplan, and Bulb turbines, including seals for blades and guide vanes,


• Framed valves: lift gates, segment gates, flap gates, roof gates, wagon gates, and cofferdams,


• Ball valves,


• Butterfly valves,


• Penstocks and their expansion sleeves,


• Servo motors and other control systems

Profiles and materials are selected based on the specific requirements of each application.

Based on the specific details of the customer’s application, PXL SEALS offers a custom-designed solution in terms of profile, material, and dimensions, taking into account various parameters and best meeting the customer’s needs and specific requirements.

1. Turbine Seals: Meeting the Demands of Hydraulic Equipment

Turbines are a critical component of a hydroelectric power plant, and the sealing systems installed on them must maintain their performance over time, despite movement and variations in operating conditions.

Kaplan turbines—both vertical and horizontal (Bulbe units)—are subject to significant stresses on their blades.

The blade seals are subjected to alternating rotational movements that occur with varying frequency depending on how the machine is operated. These critical areas therefore require seals capable of ensuring a perfect seal while maintaining their flexibility and durability over time.

PXL SEALS offers the U150-XI DE seal, a double-acting seal developed specifically for Kaplan and Bulbe turbine blades. One-piece and fully molded, it offers several advantages:

• Sealing in both directions, oil/water and water/oil;


• Quick and easy installation;


• Excellent positioning in the housing and adaptability to different dimensions;


• High stability;


• On-site molding capability thanks to the MD WAY® solution.

These solutions can be used for both original equipment manufacturing (OEM) and maintenance, repair, and overhaul (MRO).

b. Guide vane seals: Seals adapted to movement to regulate hydraulic flow

In Kaplan, bulb, or Francis turbines, the guide vanes regulate the flow of water feeding the turbine. The associated sealing systems must therefore accommodate the movement of the equipment while limiting water leakage.

- Guide vane housing seals

Guide vane housing seals ensure a watertight seal around the guide vane journals, typically for dimensions ranging from Ø50 to Ø300 mm.

The UNH seal, designed by BE PXL SEALS, is specifically tailored for this application.

Its profile features two symmetrical lips, a bead, and a central groove that ensure stable positioning.

Its main features are:

• Reliable operation at low rotational speeds;


• Vibration resistance;


• Excellent long-term durability.

- Guide vane tail seals

Guide vane tail seals play a complementary role by bearing against the guide vanes as they close, thereby limiting or eliminating water infiltration into the interior of the machine. Unlike pot seals, these seals are not standardized; therefore, each application may require a specific design study.

PXL SEALS offers various technologies depending on the turbine type and site conditions: molded seals reinforced with metal inserts, custom-profiled seals, and reinforced elastomer seals.

Frame-type gates used in hydroelectric plants, dams, and locks are subjected to significant mechanical and environmental stresses.

Segment gates, lift gates, roof gates, wagon gates, cofferdams, or flap gates: all require sealing systems capable of withstanding prolonged exposure to water, air, ozone, and temperature fluctuations.

PXL HydroRubber: an EPDM compound specifically designed for gate seals

For these applications, PXL SEALS has developed PXL HydroRubber, an EPDM 70-based elastomer compound specifically designed for gate valves and compliant with the DIN 19704 standard.

The main characteristics of PXL HydroRubber are:

• Exceptional service life;


• Excellent ozone resistance;


• Very good resistance to breakage and tearing;


• A limited environmental impact;


• Adapted to the requirements of the leading players in the hydropower industry.

The profiles are primarily manufactured by extrusion, in accordance with ISO 3302-1-E2. The product line includes, in particular:

• Music notes


• Angle profiles and flat strips


• Special profiles and molded corner blocks

To meet the needs of operators of hydroelectric power plants, dams, and locks, we offer either cast corner pieces, half-frames, or complete frames.

Where possible, the use of molded corner blocks eliminates the need for 45° cold bonding in the corners—areas that tend to be under stress and pose a significant risk of bond failure.

We manufacture two types of joints: extruded profiles and corner blocks. The two are then bonded together to form a frame. We currently offer a wide range of existing blocks and can also produce new ones to meet any specific need.

Ball valves are critical components that control the water supply to other equipment or areas within a hydroelectric facility. They regulate the water entering a power plant or flowing to a turbine, and also drain water from areas that need to be emptied.

PXL SEALS provides comprehensive sealing solutions for the various components of the ball valve: the moving rings and the trunnions;

For the moving rings, various technologies can be offered depending on the valve design and operating conditions:

• Self-lubricating NBR D-rings;


• SP and DSH D-rings made of polyurethane or reinforced NBR;


• Composite seals made of PU, PTFE, PE, etc.;


• U-seals made of NBR, reinforced NBR, or polyurethane.

For trunnions, the product line includes U-seals, composite seals, and chevron seals, with materials selected based on the application: NBR, HNBR, polyurethane, PTFE, or PE.

Butterfly valves are used primarily in hydroelectric power plants to control the flow of water between penstocks and turbines, as well as for certain drainage or regulation functions. Their function is complementary to or equivalent to that of a ball valve.

Their sealing system primarily consists of:

• The lens seal, which ensures peripheral sealing;


• The trunnion seals, which ensure sealing around the axis;


• In some cases, a seal connecting the valve body to the pipe.

Each valve has its own design characteristics, dimensions, and operating conditions. A specific analysis is therefore often necessary to determine the most suitable solution.

5. Custom Solutions for the Most Demanding Applications

Not all hydroelectric facilities can be equipped with standard solutions. When dimensions, operating conditions, or equipment design require it, PXL SEALS works with its customers to develop a customized solution.

Based on the input data and an analysis of any existing components, the engineering department proposes a tailored solution by selecting the profile, material, dimensions, and manufacturing process that best meet your needs.

If necessary, the team will propose modifications to your existing housings, indicating the functional dimensions that need to be adjusted, or will provide all the necessary elements for installing a new housing if the sealing solution is selected during the machine’s design phase.

In the case of new equipment, it is strongly recommended that you seek advice from PXL’s technical teams BEFORE manufacturing begins: this will allow you to design the housing that best suits your sealing needs, rather than trying to adapt the seal to an existing housing.

From Design to On-Site Service

PXL SEALS’ expertise extends beyond design and manufacturing.

Our team supports operators and maintenance personnel throughout the design, manufacturing, and on-site service phases, depending on the project’s stages:

• On-site assessment: Analysis of existing sealing systems and identification of constraints.


• Technical study and recommendations: Definition of the appropriate solution, technical documentation, drawings, and recommendations.


• Manufacturing at our Valserhône facility or through external partners


• Installation or assembly assistance: installation, adjustment, and inspection of seals.


• Maintenance and replacement

This ability to integrate design, manufacturing, and on-site service enables PXL SEALS to offer a comprehensive approach to hydroelectric sealing.