The Rotostat is a rotary feedthrough device designed for transferring fluids, particularly in applications involving medium pressures and high speeds. It utilizes a primary seal, typically a patented hydrostatic control mechanism, for sealing the actual feedthrough channels. Any leak chambers are sealed by a secondary seal.
Function Description
The Rotostat rotary feedthrough facilitates the transfer of fluids between stationary and rotating parts. The sealing is achieved through a seal gap, which is maintained at its default value by a patented hydrostatic control mechanism. This mechanism allows for a certain degree of "tumble" and irregular running of the shaft, ensuring effective sealing even under dynamic conditions.
The Rotostat series includes different models, namely Rotostat A, Rotostat E, and Rotostat N, each optimized for specific operating conditions and media.
- Rotostat A: These are rotary feedthroughs with gap seals, ideal for transferring fluids at medium pressures and high speeds. They are characterized by minimal viscous friction, leading to low heat generation, which is dissipated through inherent leakage. Rotostat A is designed to be insensitive to temperature fluctuations and pressure impacts.
- Rotostat E: Similar to Rotostat A, Rotostat E models are also rotary feedthroughs with gap seals for medium pressures and speeds. The sealing between stationary and rotating parts is achieved via a patented, hydrostatic-controlled "floating sleeve." These "floating sleeves" are arranged concentrically around the rotating shaft. Even at high speeds and pressures, only viscous friction occurs, resulting in minimal heat generation dissipated by inherent leakage. Rotostat E is also designed to be insensitive to temperature fluctuations and pressure impacts.
- Rotostat N: Rotostat N models are rotary feedthroughs with gap seals for transferring fluids at medium pressures and high speeds. The seals between stationary and rotating parts are maintained by a patented hydrostatic control mechanism that allows for "tumble" and irregular running of the shaft. A complex, inverse hydrostatic gap regulator ensures that the gap between stationary and rotating parts remains minimal (a few µm) even at high pressures, resulting in very low leakage. Rotostat N is insensitive to temperature variations, dirt, and pressure impacts.
Rotokombi (Option): The Rotokombi design offers a modular solution, allowing the Rotostat devices to be combined with other media feedthroughs from the manufacturer. This enables the transfer of additional components for gas, water, grease, and oil, as well as electrical currents and air. The Rotokombi utilizes optimal sealing technology for each medium, providing a complete solution from a single source with no interface problems between individual components.
Important Technical Specifications
The device's type plate, located on the housing, provides specific information including:
- Manufacturer
- Type
- Item number
- Serial number
- Order number
- Maximum pressure
- Maximum speed
Operating Conditions:
- Temperature range: -20 to +80 °C
- Maximum relative humidity: non-condensing, 0 to 80 %
- Protection class as per type plate
Leakage Rate (Examples for Rotostat A, E, N):
- Rotostat A (Hydraulic fluid with 20 cm²/s viscosity at 7.0 MPa):
- Without revolution speed: 0.075 l/min (30 A), 0.12 l/min (50 A), 0.15 l/min (65 A), 0.3 l/min (80 A), 0.4 l/min (100 A), 0.7 l/min (125 A), 1 l/min (150 A)
- At 1500 min⁻¹: 0.15 l/min (30 A), 0.2 l/min (50 A), 0.4 l/min (65 A), 0.7 l/min (80 A), 0.9 l/min (100 A), 1.6 l/min (125 A), 2.3 l/min (150 A)
- At 3000 min⁻¹: 0.2 l/min (30 A), 0.4 l/min (50 A), 0.6 l/min (65 A), 1 l/min (80 A), 1.5 l/min (100 A), 2.5 l/min (125 A), 3.4 l/min (150 A)
- Rotostat E (Hydraulic fluid with 46 cm²/s viscosity at 21.0 MPa):
- 100 cm³/min (25 E), 500 cm³/min (40 E), 850 cm³/min (60 E), 1050 cm³/min (80 E)
- Rotostat N (Hydraulic fluid with 20 cm²/s viscosity at 15.0 MPa):
- 0 min⁻¹: 0.2 l/min (30 NX), 0.6 l/min (80 NX), 1.3 l/min (140 NX), 2.6 l/min (200 NX)
- 1500 min⁻¹: 0.3 l/min (30 NX), 1.2 l/min (80 NX), 2.7 l/min (140 NX), 4.5 l/min (200 NX)
- 3000 min⁻¹: 0.5 l/min (30 NX), 1.7 l/min (80 NX), 3.4 l/min (140 NX)
Tolerances for Installation:
- For speeds up to 3,000 min⁻¹, radial run-out tolerance: 12 µm; axial run-out tolerance: 10 µm (referenced to the rotary axis).
- For actuators with hexagons or spanner flats on the rotating component, radial run-out tolerance: 7 µm (referenced to the rotary axis).
- Surfaces over which seals slide must be machined Ra ≤ 0.4 µm without twisting.
Usage Features
- Proper Use: Rotostat devices are exclusively designed as rotary feedthroughs for transferring media. All relevant information, including type plate, order documents, and drawings, must be considered for specifications, operating conditions, limits for use, and areas of application.
- Technical Properties (General):
- No static friction and stick/slip effects.
- Medium operating pressure at simultaneous high speeds.
- Minor leak.
- Minor mechanical performance loss.
- Highly resistant to temperatures.
- Compatible with almost any fluid, including non-lubricating ones.
- Maintenance-free.
- Filtering: To ensure fault-free operation, transferred media must be continuously filtered. Foreign bodies larger than 10 µm must be filtered off. The specified filter fineness is a reference value, and actual operating conditions should be considered. Coarser filtering generally leads to a shorter seal service life.
- Hydraulic Switch: A hydraulic switch is recommended to ensure the required minimum pressure during rotation.
- Initial Commissioning:
- The device is only permissible within the specified operating limits.
- Minimum pressure of 0.5 MPa is required; lower pressures can lead to premature failure.
- The device is not suitable for pressure retention without indicated flow.
- No deformations must form from pressure or temperature.
- Can decrease the boring or increase the shaft size.
- Can achieve an over-temperature towards the housing of more than 30 °C.
- The leakage amounts and temperature of the operating medium and the rotary feedthrough must be checked.
Maintenance Features
- Maintenance Schedule: The device is largely maintenance-free, and no maintenance work can be performed on interior components. Cleaning, checking media lines, and measuring leakage amount should be performed daily.
- Cleaning the Device:
- Only approved cleaning agents and methods should be used.
- Never clean with compressed air, steam, or water jet devices.
- Do not use petroleum, benzene, turpentine, acetone, cleaners with solvent content, or sharp-edged objects (e.g., wire brushes, sandpaper).
- The exterior of the housing should be cleaned with a clean, dry, and lint-free cloth.
- Checking Media Lines: All connections and lines should be checked for leaks and damage, and replaced if necessary.
- Cartridge Element: Pressurize the cartridge element with only 1.0 MPa pressure and slowly rotate. The shaft must be easy to rotate without tilting and clamping points. If not possible, the rotary feedthrough element is stuck or damaged and needs to be sent to the manufacturer.
- Disassembly and Disposal:
- Disconnect all transferred media, place a drip tray for leaking media, and disconnect media connections.
- Collect any leaking media.
- Secure the device before unfastening screws to prevent crushing.
- Dismantled components should be sent for recycling if no return or disposal agreement exists. This includes scrap metals, plastic elements, and other components sorted by material composition.
- Disposal must comply with environmental regulations and be handled by authorized specialist companies.
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