Knowledge about penstocks, non-return valves and channel penstocks
In this knowledge section, planners, operators, construction managers and installers will find technical answers regarding the selection, planning, installation and maintenance of penstocks, non-return valves and channel penstocks.
The content covers standard designs as well as special structural geometries, custom-made products, electric actuators and existing systems. In addition, digital tools are available for configuration, flow calculation and structural planning.
For project-specific questions, TESACO provides direct support based on drawings, photos or a few technical key data.
Total FAQ Overview
1. Information search & basics
- What is the difference between a threaded spindle penstock and a throttling penstock?
- How does a non-return valve work and when does it close automatically?
- When should stainless steel 1.4301 and when should 1.4571 or 1.4404 be used in hydraulic engineering?
- What does the DIN 19569-4 standard mean for penstocks and how much leakage is permitted?
- What is the difference between above-ground and underground penstock operation?
- How does a manhole adapter with a sealing collar work for round concrete manholes?
- When are a float cover or a pendulum weight an advantage on a non-return valve?
- What is meant by a four-sided sealing valve in the wastewater sector?
- Why are channel penstocks used in open channels instead of standard penstocks?
- Must a penstock according to DIN 19569-4 always be 100% drip-tight?
- What is the difference between a channel penstock (H-series) and a large penstock (K-series)?
- What is the minimum opening pressure for TESACO non-return valves with a vertical flap?
- When is an inclined flap useful for non-return valves?
- Why is a gearbox installed between handwheels for large gate valves?
- What is the advantage of a drill-free clamping assembly with long nuts in the shaft?
2. Application & Technical Planning
- Which shut-off and control valves are typically used in a stormwater retention basin (SRB)?
- Which gate valve is recommended for an emergency basin with chemically or hydraulically demanding media?
- Which valve protects a sewer outlet fully automatically and without external power from backflow?
- How can the throttle opening for a storm overflow basin (SOB) be calculated exactly?
- Which non-return flap is suitable for installation on inclined embankment sections (e.g., slope 2:3 or 1:1.5)?
- How can gate valves be mounted in round precast shafts without drilling?
- Can a manually operated gate valve be retrofitted with an electric actuator?
- What can I do if the minimum installation depth for a stem extension is not met in the shaft?
- Which valve type is suitable for shutting off pump sumps, inlets, and bypasses in pumping stations?
- Can a channel sluice gate be adapted to custom-shaped channel cross-sections or inclined watercourse beds?
- How does TESACO support concrete works in integrating gate valves into precast shafts?
- Which gate valves and sluices are installed in sewage treatment plants for automated basin control?
- Which shut-off valves are used in mobile and stationary flood protection?
- How do you secure channel outlets at watercourses against debris and vandalism?
- How are K-series large sluice gates designed for wide relief structures?
3. Purchase, Supplier Search & Manufacturer Selection
- What should engineers and planners look for when selecting manufacturers and dimensioning throttle valves?
- Where can one obtain standard stainless steel sluice gates (e.g., DN 300 in 1.4571) with extremely short ex-works delivery times?
- Which manufacturer produces backflow flaps with a spigot end for direct insertion into sewer pipes?
- Are custom-made sluice gates and channel gates for extremely high pressure loads or XXL dimensions available from TESACO?
- What digital planning data and configurators does TESACO provide for engineering offices?
- Does TESACO offer a complete service including on-site measurement, manufacturing, and installation?
- Does TESACO offer factory-preassembled sluice gate and backflow flap systems for round manholes?
- What is TESACO's delivery timeframe for sluice gates with electric actuators (e.g., AUMA)?
- Does TESACO offer maintenance and seal replacement for existing sluice gate systems and third-party products?
- What information does TESACO need to provide a quote on the same business day?
- Does TESACO also offer flange versions for connection to existing pipelines?
- Which material certificates according to EN 10204 does TESACO issue for hydraulic engineering projects?
- How does TESACO support civil engineering companies with short-term site requirements?
- Who handles the mechanical and electrical commissioning of sluice gates with electric actuators?
- According to which quality standards does TESACO produce its shut-off and control valves?
1. Information search & basics
What is the difference between a threaded gate and a throttling gate?
C-series threaded gates and F-series throttling gates are based on the same robust basic design according to DIN 19569-4, but they differ fundamentally in their hydraulic function:
- Threaded gates (C-series): Primarily used for the complete shut-off of water flows. The gate plate is standardly opened completely or closed with a four-sided seal to drain structures or plant components for maintenance and inspection work.
- Throttling gates (F-series): Serve as control gates for the targeted limitation of flow. The gate plate remains at an accurately calculated opening, which is set via an integrated stroke scale. The required plate opening is determined in advance using the TESACO flow calculator.
How does a non-return flap work and when does it close automatically?
A non-return flap (G-series) prevents water from flowing back from watercourses, lakes, or channels into the structure automatically and without external auxiliary energy:
- Normal operation: If water pressure builds up on the channel or structure side, the vertical flap cover opens automatically due to the flow.
- Backwater case: If the water level rises on the watercourse side, the backflowing water presses the flap cover tightly against the frame seal from the outside and reliably closes the line.
When should stainless steel 1.4301 be used in hydraulic engineering and when should 1.4571 or 1.4404 be used?
The choice of material depends on the medium, the chloride load, and the local cleaning chemicals:
- Stainless steel 1.4301 (V2A): Is the proven standard material for typical wastewater applications, rainwater, storm basins, and standard hydraulic structures.
- Stainless steel 1.4571 / 1.4404 (V4A): Offer higher corrosion resistance and are used in areas with increased chloride load, in sewage treatment plants, industrial wastewater, landfill leachate, or aggressive chemical environments.
What does the DIN 19569-4 standard for shut-off gates mean and how much leakage is allowed?
DIN 19569-4 is the authoritative standard for valves in hydraulic engineering and regulates basic design, dimensioning, and leakage rates. TESACO standard gates are designed as four-sided sealing gates for a standard pressure load of 6 m water column according to this standard. Professionally installed TESACO gates operate significantly below the normatively permissible leakage values.
What is the difference between above-ground and underground gate operation?
The difference lies in the positioning of the operating element in relation to the upper edge of the structure:
- Underground operation: The entire operation remains below the ground or ceiling edge. It is typical for operation on traffic areas via an operating square in a surface box using a T-key.
- Above-ground operation: The actuator is freely accessible above the structure – for example, on an operating platform or wall via an actuator pedestal with a handwheel, gearbox, or electric actuator.
How does a shaft adapter with a sealing collar work on round concrete shafts?
When flat gates or flaps are mounted on the curved walls of round shafts (DN 1000 to DN 2000), a cavity is created. The TESACO shaft adapters (E15-001 for gates, E15-005 for flaps) have a firmly welded, circumferential sealing collar. This creates a flat mounting surface against the shaft wall, which is sealed with elastic sealant – time-consuming casting with concrete or mortar is completely eliminated.
When do a hollow float cover or a pendulum weight offer advantages on a non-return flap?
Both options change the hydraulic opening and closing behavior of the G-series non-return flap:
- Hollow float cover: Due to its inherent buoyancy in water, the required opening force is reduced and the hydraulic resistance in the channel decreases.
- Pendulum weight: Via adjustable lever arms, the weight can be balanced so that either the opening pressure is specifically reduced or the closing moment under counter-pressure is increased.
What is meant by a four-sided sealing valve in the wastewater sector?
A four-sided sealing valve (like the TESACO C-series) is equipped with a circumferential, replaceable profile seal (EPDM as standard), which seals the gate plate against the frame on all four outer edges. This guarantees a reliable separation against water columns in pipes, shafts, or basins.
Why are channel penstocks used instead of normal gates in open channels?
In open channels, an upper wall is missing, which is why three-sided sealing H-series channel penstocks are used. They always have an upper cross-beam to guide the spindle and are exactly adapted to channel width, channel height, and water level. For very wide channels, K-series large penstocks with double spindles prevent the plate from tilting.
Must a shut-off gate according to DIN 19569-4 always be 100% drip-free?
No, the DIN 19569-4 standard defines permissible leakage rates depending on the water column and the pressure curve. Absolute drip-free sealing is not normatively required; however, professionally installed TESACO gates in practice fall significantly below these limit values.
What is the difference between a channel penstock (H-series) and a large penstock (K-series)?
- Channel gates (H-Series): Used for three-sided sealing applications in narrow to medium-width channel cross-sections and driven by a spindle.
- Large gates (K-Series): Installed in very wide channels (often wider than they are high). To prevent the gate leaf from tilting, large gates are designed as a double-spindle version, which is moved synchronously via two gearboxes or coupled electric actuators. TESACO has already implemented widths of approximately 5 m here.
What is the minimum opening pressure for TESACO non-return flap valves with a vertical lid?
For TESACO non-return flap valves with a standard vertical lid, the required minimum opening pressure ranges between approx. 20 mm water column (for DN 150) and 80 mm water column (for DN 1200), depending on the nominal diameter. The vertical lid ensures that the flap opens sensitively even with minimal backwater and keeps the flow resistance in the channel low.
When is an inclined flap lid useful for non-return flap valves?
An inclined flap lid is chosen if the flap is intended to have deliberate damping properties or if a higher closing pressure is desired to prevent unintentional opening due to slight wave movements on the water side. This increases the required opening pressure in a targeted manner as a functional feature.
Why is a gearbox used with handwheels for large gates?
For large nominal diameters (e.g., from DN 500 upwards) or high water columns, the torque required to lift the gate plate increases significantly. A handwheel with a gearbox reduces the force required: the necessary manual effort is reduced to an easily manageable level, although more rotations are required to open or close it.
What is the advantage of a drill-free clamping installation with long nuts in the manhole?
With the clamping installation, the gate unit is tensioned directly against the existing channel recess of the concrete manhole using long nuts. The concrete channel serves as a counter-bearing, which means no holes need to be drilled and no anchor rods need to be set. This protects the manhole structure and drastically reduces installation time.
2. Application & Technical Planning
Which shut-off and control valves are typically used in a stormwater retention basin (SRB)?
Three coordinated types of valves from TESACO are usually used in a stormwater retention basin:
- Flow control: For defined basin discharge, TESACO uses F-Series throttle valves that remain at a calculated plate opening to hydraulically limit the discharge.
- Emergency shut-off & maintenance: For complete shut-off, four-sided sealing C-Series threaded gates (acc. to DIN 19569-4) are used, enabling draining for inspection work.
- Backflow protection: To prevent water from flowing in from the receiving water body, G-Series non-return flap valves or flex non-return flap valves (G11-Series) are installed at the outlet.
Which shut-off gate is recommended for an accident basin with chemically or hydraulically demanding media?
For accident basins, industrial plants, and logistics centers, TESACO uses four-sided sealing C-Series threaded gates. Since accident basins must contain aggressive media or contaminated fire-extinguishing water in an emergency, they are preferably manufactured in stainless steel 1.4571 (V4A) and the EPDM seals are adapted to the specific project. They can be equipped with AUMA electric actuators and connected directly to fire alarm systems or building management systems to close automatically in an emergency.
Which valve protects a channel outlet fully automatically and without auxiliary energy against backflow?
For automatic backflow protection at water outlets, TESACO offers G-Series stainless steel non-return flap valves and G11-Series flex non-return flap valves. The flaps open automatically under normal channel pressure and close when the external water level rises without external energy supply due to the counter-pressure of the water column. They are available as a dowel version, flange version, manhole adapter, or spigot-end version.
How can the throttle opening for a stormwater overflow basin (SOB) be calculated precisely?
For the hydraulic design of an F-Series throttle gate, the nominal diameter of the discharge pipe, the maximum backwater height in the basin, and the permissible discharge ($Q$ in l/s) are required. Using the digital TESACO flow calculator, the plate opening is calculated exactly and set on the gate’s control scale. For complex backwater conditions, TESACO additionally creates project-specific throttle characteristic curves.
Which non-return flap valve is suitable for installation on sloping embankment sections (e.g., slope 2:3 or 1:1.5)?
On sloping embankment outlets, rigid stainless steel lids reach their limits. TESACO uses the Flex non-return flap valve (G11-Series) with a flexible EPDM lid here. This closes precisely even in an inclined position and requires little installation space. TESACO manufactures the frame geometry to fit the exact slope (e.g., 2:3 or 1:1.5) for doweling or inserting.
How can shut-off gates be installed in round prefabricated manholes without drilling?
For monolithic round manholes (DN 1000, 1200, 1500, 2000), TESACO offers manhole adapters (type E15-001) with long nut clamping installation. The gate unit is tensioned against the channel recess using long nuts (the channel serves as a counter-bearing) without the need for drilling or anchor rods. A circumferential sealing collar seals the adapter without the need for mortar casting.
Can a manually operated gate be retrofitted with an electric actuator?
Yes, all TESACO C- and F-Series gates can be retrofitted with an electric actuator (e.g., AUMA) at any time. Preparation during the initial order is not required. TESACO determines the suitable consoles and connection components for retrofitting based on the nominal diameter and structure depth.
What can I do if the minimum installation depth for a spindle extension is not met in the manhole?
For very shallow structure depths, TESACO develops space-saving special designs. These include adapted frame heights, offset consoles, deflection gearboxes with shaft joints, or versions as hand-pull gates for smaller channels. The basis for this is a simple structural cross-section.
Which valve type is suitable for shutting off pump sumps, inlets, and bypasses in pumping stations?
In pumping stations, four-sided sealing stainless steel C-Series gates are used. They serve to shut off inlet pipes, pump sumps, or bypasses during inspection work. Depending on the space available, installation is carried out via anchor rods on the concrete wall, on flanges, or via manhole adapters. Since they are operated frequently, they are often equipped with actuator pedestals, gearboxes, or AUMA electric actuators.
Can a channel gate be adapted to specially shaped channel cross-sections or inclined channel bottoms?
Yes, TESACO manufactures H-series channel gates and K-series large-scale gates as project-specific custom designs. Special profiles such as inclined channel bottoms, trapezoidal profiles, or stepped bottoms are also accommodated by precisely adapting the sealing profile of the three-sided sealing gates (according to DIN 19569-4).
How does TESACO support concrete plants in the integration of slide gates into precast concrete manholes?
For concrete and precast plants, TESACO offers factory-tuned manhole adapters (E15-001/E15-005) and drill-free long-nut versions. TESACO provides interactive planning drawings and CAD files (DWG/DXF) during the manhole planning phase so that recesses can be precisely coordinated, minimizing effort at the concrete plant.
Which slide gates and sluice gates are installed in wastewater treatment plants for automated tank controls?
In wastewater treatment plants, four-sided sealing threaded slide gates (C-series) are used in closed pipes, and three-sided sealing channel gates (H-series) are used in open channels. Since they are integrated into automated processes, they are equipped with electric actuators and connected to the existing building management system (BMS). The preferred material is stainless steel 1.4571 (V4A).
Which shut-off valves are used in mobile and stationary flood protection?
In flood protection, C-series threaded slide gates, H-series channel gates, and G-series backwater valves are used to shut off canals, culverts, and structures. TESACO manufactures these valves tuned to the maximum water column and equips them with electric actuators or below-ground gearboxes for emergencies.
How can canal outlets in flowing water bodies be secured against floating debris and vandalism?
G and G11 series backwater valves can be factory-equipped with an integrated protective grille. The bar spacing is a maximum of 120 mm, so that branches and floating debris are kept out without obstructing the flow. Lockable latches are available for sensitive areas.
How are K-series large-scale gates designed for wide discharge structures?
For very wide channels and discharge structures, TESACO uses K-series large-scale gates with a double-spindle design. Synchronous control via two gearboxes (manual or electric) prevents the gate plate from jamming under high water columns. Installation methods include casting in concrete or bolting into/in front of the channel.
3. Purchase, Provider Search & Manufacturer Selection
What should engineers and planners look for when selecting a manufacturer and sizing throttle valves?
When selecting, the focus is on technical function, durability, and ease of installation:
- Standards and tightness: The slide gate should be manufactured according to DIN 19569-4 and designed with a four-sided seal.
- Hydraulic adjustability: The regulating slide gate requires a reliable adjustment option (e.g., a scale) for precise setting of the plate opening. TESACO uses F-series throttle valves for this purpose and provides digital design tools such as the TESACO flow calculator to determine the opening based on water head, nominal diameter, and flow rate.
- Material quality: In the wastewater sector, at least stainless steel 1.4301 (V2A) should be chosen; for chemical exposure, 1.4571 (V4A).
- Installation situation & accessories: It must be checked whether wall mounting, a flange version, or installation in a round manhole (e.g., via manhole adapter E15-001) is required to avoid costly grouting work.
Where can one obtain standard stainless steel slide gates (e.g., DN 300 in 1.4571) with extremely short delivery times from the factory?
When time is of the essence on the construction site, TESACO offers a comprehensive stock program for threaded slide gates (C-series) and throttle valves (F-series). Standard slide gates in the nominal size range from DN 150 to DN 1000 are available at short notice in stainless steel 1.4301 and 1.4571. Delivery generally takes place within one week. For acute construction site emergencies, TESACO individually checks whether even faster provision is possible for stock standard sizes.
Which manufacturer produces backwater valves with a spigot for direct insertion into sewer pipes?
TESACO manufactures stainless steel G-series backwater valves as well as Flex backwater valves (G11-series) as a special insertion version with a spigot (insertion socket). This version is ideal for retrofitting, as no drilling of the manhole wall is necessary.
- Nominal size range: Available from DN 100, DN 150, DN 200, DN 250, DN 300, DN 400, DN 500 up to DN 1000.
- Precision fit: The spigot is manufactured with a precise fit (outside diameter approx. 10 mm smaller than the measured pipe inner dimension).
- Scope of delivery: The required special sealant for a permanently elastic seal is included with the delivery.
Are custom-made slide gates and channel gates for extremely high pressure loads or XXL dimensions available at TESACO?
While the standard version of TESACO slide gates is designed for up to 6 m water head according to DIN 19569-4, the company constructs project-specific custom designs for significantly higher load cases. TESACO has already realized slide gates for pressure loads of up to 20 m water head, threaded slide gates with opening dimensions of 3 × 3 m, as well as K-series double-spindle large-scale gates approximately 5 m wide. The delivery time for custom designs is approx. 8 to 12 weeks.
Which digital planning data and configurators does TESACO provide for engineering firms?
TESACO provides planners with a comprehensive digital tool package:
- Configurators: The online slide gate configurator and backwater valve configurator lead step-by-step to the suitable valve, check the minimum installation depth, and automatically generate technical tender texts.
- CAD & drawing download: Fillable planning drawings (PDF) as well as CAD files in DWG and DXF formats are available for standard valves (DN 100 to DN 1000).
- Flow calculator: A tool for precision calculation of throttle openings.
Does TESACO offer a complete service from on-site measurement, production, and installation?
Yes, TESACO offers a full-service package from a single source upon request:
- On-site measurement: For existing structures or unclear manhole geometries, TESACO technicians take the measurements directly at the site.
- Installation & commissioning: The service team handles the professional mechanical installation of slide gates, backwater valves, manhole adapters, linkages, and actuators, as well as the initial on-site commissioning (lead time approx. 1 to 2 weeks).
Does TESACO offer factory-pre-assembled slide gate and backwater valve systems for round manholes?
TESACO offers manhole adapters E15-001 (for C and F series slide gates) and E15-005 (for G-series backwater valves) for round precast manholes. The system covers valve sizes from DN 150 to DN 500 for round manholes DN 1000, 1200, 1500, and 2000. The valve and manhole adapter are factory-coordinated, pre-assembled, and sealed, which drastically simplifies manhole installation.
What delivery time applies at TESACO for slide gates with electric actuators (e.g., AUMA)?
The delivery time depends on the availability of the electric actuator. Standard AUMA actuators (up to DN 600, 400 V) are often available within 1 to 4 weeks. For time-critical projects, the slide gate can be delivered and installed in advance; the AUMA actuator can then be easily mounted onto the prepared bracket once delivered.
Does TESACO offer maintenance and seal replacement for existing slide gate systems and third-party products?
TESACO performs service work on its own valves as well as (after technical inspection) on third-party products and older cast iron gates. For TESACO threaded slide gates, the EPDM profile seals can be replaced while installed, without removing the frame from the wall. Replacement seals for third-party products are also reviewed.
What information does TESACO need to provide a quote on the same business day?
For a quote on the same business day, the following are sufficient:
- Product type (threaded slide gate, throttle slide gate, backflow flap, channel gate).
- Nominal width (e.g., DN 200) or clear opening dimensions.
- Installation situation (straight wall, flange, or circular manhole).
- Actuation method (key, handwheel, gearbox, electric actuator).
Sketches or site photos will further speed up processing.
Does TESACO also offer flange versions for connection to existing piping?
Yes, TESACO supplies C- and F-series slide gates and G-series backflow flaps as flange versions. The standard design for flaps matches the PN10 hole pattern (PN16 is also possible). Flange versions serve as adapters to existing pipe flanges and are manufactured project-specifically.
Which material certificates according to EN 10204 does TESACO issue for hydraulic engineering projects?
In addition to operating, assembly, and maintenance instructions as well as technical drawings, TESACO provides factory certificates, manufacturer declarations, and material certificates according to EN 10204 (e.g., inspection certificate 3.1) for all stainless steel components upon request.
How does TESACO support civil engineering companies with short-term dimension adjustments on the construction site?
On construction sites, TESACO technicians coordinate directly with site managers and foremen regarding unexpected site dimensions. Thanks to a broad inventory of standard sizes and adaptable brackets, dimensional adjustments and follow-up deliveries can be handled unbureaucratically.
Who handles the mechanical and electrical commissioning of slide gates with electric actuators?
TESACO handles the mechanical installation, the setting of limit and torque switches, and the on-site mechanical commissioning. The final electrical connection to the power supply and control system is carried out by an on-site electrical contractor as agreed.
According to which quality standards does TESACO produce its shut-off and control valves?
TESACO produces all valves according to an ISO 9001 certified quality management system. Design and leak testing are strictly carried out in accordance with the hydraulic engineering standard DIN 19569-4.