Our solutions for demanding wastewater applications
Technical requirements in wastewater plants
In biogas and wastewater treatment plants, corrosion, constant moisture and mechanical loads interact continuously. Vibrations, alternating loads and limited accessibility have a major impact on the design, installation and service life of rope and support systems. Plant-specific boundary conditions such as the medium, temperature and maintenance intervals must also be taken into account.
Talk to us about your application.
Do you have a specific task or need a technically robust solution for your plant? We support you with selection, design and implementation.
Ropes for agitator suspensions
Agitator suspension systems in biogas and wastewater treatment plants are permanently exposed to corrosive media, moisture and dynamic loads. Vibrations, alternating loads and limited accessibility place high demands on rope material, design and end terminations. Key factors are application-specific dimensioning and a durable, operationally reliable assembly. Depending on the application, BVM supplies different rope solutions – from HMPE fibre ropes such as BVM-Biotec to stainless-steel wire ropes and special wire ropes for particular load cases or ambient conditions. Selection and execution are always based on the medium, load spectrum, temperature, deflection and installation concept.
BVM-Biotec 2000-8® – fibre rope for agitator suspensions
BVM-Biotec 2000-8® is a fibre-rope solution developed specifically for agitator suspensions. It combines high fatigue strength with excellent resistance to corrosive media and reduces shock and alternating loads during operation.
✓ Shock-absorbing in vibration-intensive operation
✓ Very high resistance to moisture, H₂S and condensate
✓ Electrically non-conductive, insensitive to leakage currents
✓ Low weight, easy to install
Why this rope achieves significantly longer service life in many plants – read more here.
Technical details & application notes for BVM-Biotec 2000-8®
Technical background
Agitator suspensions are continuously exposed to a combination of chemically aggressive media, moisture, alternating loads and vibration. Conventional wire ropes often respond with corrosion, fatigue failures or hard-to-predict damage patterns, especially around the gas/liquid interface.
BVM-Biotec 2000-8® was developed specifically for this combination of loads.
Key technical advantages
High fatigue strength and shock absorption
The HMPE core provides elastic compliance and reduces peak loads, as they occur with “jumping” or vibrating agitators. This significantly reduces the rope’s mechanical fatigue.
Very high corrosion and chemical resistance
Moisture, hydrogen sulphide and condensing media do not attack the rope material. Corrosion-related loss of cross-section is eliminated entirely.
Electrically non-conductive
BVM-Biotec 2000-8® is electrically insulating. Electrochemical effects, leakage currents and resulting pitting corrosion are excluded by design.
Predictable operating behaviour
No passive-layer damage, no wire breaks, no progressive corrosion processes. Changes to the rope are visually detectable and predictable.
Low weight
Facilitates installation, height adjustment and service work, especially where access is limited.
System-related considerations
The surface hardness of a fibre rope is lower than that of a wire rope. Rope-friendly guidance, suitable cable hangers and clean deflections must therefore be part of the overall design. In practice, this can be reliably managed with properly matched peripheral components.
Typical applications
-
vibration-intensive agitator suspensions
-
plants with known fatigue or corrosion issues
-
frequent height adjustment
-
critical gas/liquid interfaces
-
plants with electrochemical influences
The performance of BVM-Biotec 2000-8® results from the interaction of the rope, guidance, end terminations and operating conditions. Final design is always application-specific.
AGR Standard – stainless-steel wire rope for agitator suspensions
AGR Standard is a proven, widely used wire-rope solution for agitator suspensions in biogas plants. Under suitable operating conditions, it provides a cost-effective and reliable solution with predictable maintenance effort.
✓ A4 stainless steel (1.4401 / 1.4571)
✓ Cost-effective, widely used standard solution
✓ Available in various diameters
✓ Customer-specific end terminations (eye, terminal, fork, etc.)
Find out here which operating conditions the AGR Standard is suitable for.
Technical details & operating limits of AGR Standard
Technical classification
A4 stainless-steel wire ropes have been used successfully for agitator suspensions for many years. AGR Standard is based on a proven rope construction and is particularly suitable for plants with moderate chemical and mechanical loads.
Typical benefits
-
Proven wire-rope construction with excellent value for money
-
High mechanical strength
-
Cost-effective solution for many standard applications
-
Compatible with common end terminations and guidance systems
Operating conditions
AGR Standard is suitable when:
-
the chemical exposure is moderate
-
clean deflection is ensured
-
vibration and shock loads are limited
-
all metallic components are properly earthed
Typical limitations
-
corrosion at the gas/liquid interface is possible
-
susceptible to hydrogen sulphide condensates
-
no shock absorption in vibration-intensive operation
-
regular inspection of the hot-spot area is required
Classification
AGR Standard is a functional and cost-effective solution when the boundary conditions are right. In cases of increased vibration, aggressive media or known service-life issues, alternative rope solutions should be considered.
AGR-Extreme – highly corrosion-resistant wire rope for agitator suspensions
AGR-Extreme is a specially developed wire rope for agitator suspensions in highly corrosive environments. It is used where standard stainless-steel ropes reach their limits prematurely due to aggressive media, condensates or chemical exposure.
✓ High-alloy, corrosion-resistant stainless steel
✓ Significantly increased resistance at gas/liquid interfaces
✓ Optional surface-hardened for increased wear resistance
✓ Available with customer-specific end terminations
Find out here when a special wire rope is the right choice.
Technical details & applications of AGR-Extreme
Technical classification
In many biogas plants, the gas/liquid interface is a particularly critical zone. Hydrogen sulphide can condense into aggressive media that attack the passive layer of standard stainless steel and may lead to accelerated corrosion.
AGR-Extreme was developed specifically for these operating conditions.
Key technical feautures
-
High-alloy stainless steel with significantly improved corrosion resistance
-
Optimised rope construction for increased mechanical load capacity
-
Optional surface-hardened (>1000 HV) to reduce abrasion and wear
-
Suitable for continuously wet and chemically exposed environments
Typical applications
-
Use in aggressive media and condensate zones
-
plants with known corrosion issues
-
high mechanical stress in corrosive environments
-
applications with increased requirements for service life and operational reliability
Positioning versus other rope solutions
AGR-Extreme offers significantly higher corrosion resistance than standard stainless-steel ropes. Compared with fibre ropes, it has higher surface hardness but no shock-absorbing properties. Selection should therefore always be made in the context of the overall load situation.
Design note
The performance of AGR-Extreme depends largely on guidance, end terminations, earthing and peripheral components. A system-level assessment is required, especially in corrosive zones.
Shackles for agitator suspensions
Depending on the load case and installation situation, different shackle types are used to attach the ropes to agitators.
Our complete shackle catalogue (PDF)
Carabiners, shackles and swivels in stainless steel and aluminium
Cable holders for agitator suspensions
In many plants, power and control cables are routed along the agitator suspension. Vibration, self-weight and restricted movement continuously act on the cable hangers, fastening elements and rope. The cable-hanger design has a major influence on wear behaviour within the overall system.
BVM cable hangers are designed for these operating conditions and engineered as system components – matched to the rope, fastening method and operating mode.
All BVM cable holders include:
✓ two-piece cable hanger made of acid-resistant polymer
✓ secure clamping of the power cable
✓ cable routing along the agitator suspension
✓ sizes for cable diameters 10–16 / 17–25 / 26–36 mm
Curved cable holder with stainless-steel U-bolt
A proven and cost-effective standard solution for routing agitator cables. The cable hanger is clamped with a stainless-steel U-bolt and is typically attached to the rope via a shackle. This results in comparatively rigid cable routing.
Features
✓ A4 stainless-steel U-bolt, guided laterally through the cable hanger
✓ robust, simple design
✓ cost-effective solution for many standard applications
✓ Suitable for steady operation with low relative movement
Curved cable holder with swivel fork shackle
This version provides a more flexible connection of the cable hanger to the rope. A freely rotating and swivelling fork shackle allows the cable to follow agitator movements more effectively.
Features
✓ Bolted design with retaining plate
✓ integrated swivel fork shackle, freely rotating and swivelling
✓ reduced twisting and cable strain
✓ Proven in variable operating conditions and increased movement
Curved cable holder with rope-protection
The premium version adds an acid-resistant polymer rope-protection bush to the swivel fork shackle. This prevents metallic connecting parts from coming into direct contact with the wire rope.
Features
✓ Rope-protection bush separates shackle and wire rope
✓ reduces local surface wear
✓ wear is intentionally shifted to the polymer bush
✓ Particularly useful where the rope position is constant over long periods and vibration levels are elevated
Critical rope zone and positioning of cable hangers
In practice, the rope section around one metre above the agitator is subject to particularly high stress. In this zone, corrosive influences at the transition between liquid and gaseous media often overlap with mechanical loads from the agitator’s surge and vibration zone. In addition, several cable hangers may accumulate in this section, depending on the installation situation and cable length.
For targeted positioning of the cable hangers, BVM can optionally supply heavy-duty wire-rope clamps that can be attached freely on the rope. They limit unintended slipping of the cable hangers in this high-stress zone and make load distribution more reproducible.
Winches for agitator suspensions
BVM supplies selected stainless-steel console winches for wire-rope and fibre-rope applications in agitator suspensions.
Stainless-steel console winch – version for BVM-Biotec
Approved for operation with the HMPE fibre rope BVM-Biotec 2000-8®
Stainless-steel console winch – version for wire rope
Approved for operation with wire ropes up to 900 kg load capacity.
Further informations
When using fibre ropes, the winch is a safety-critical system component. The stainless-steel console winch shown here is approved for wire-rope operation and—when supplied in an adapted version—for operation with the HMPE fibre rope BVM-Biotec 2000-8®.
Approval for BVM-Biotec is based on an adapted rope attachment and a correspondingly reduced permissible load. This ensures that the use of the fibre rope on the winch is technically validated and documented.
In wastewater applications, especially in treatment plants, additional winch designs are also used.