The Parker PrädifaBU Ultrathan® rod seal is a compact seal with an integrated anti-extrusion ring. It is frequently used as a buffer seal within sealing systems such as those utilized in construction machine cylinders. Construction machine cylinders operate in harsh conditions in which pressure peaks of up to 1000 bar frequently occur. The BU rod seal is installed upstream to isolate such loads from the secondary seal. Due to its special shape, the seal (like a return valve) is able to return pressure that may build up between the primary and the secondary seal into the system. A single or tandem arrangement of this product series is possible as well.
- Enhanced sealing performance in non-pressurized
- Robust seal profile for harshest operating conditions.
- Extreme wear
- Insensitive to extreme pressure
- Extremely high extrusion resistance.
- Excellent media resistance in case of suitable compound
- Suitable compounds available for special requirements of the chemical process industry.
- Suitable compounds available for special requirements of the food processing
- Dimensions according to ISO
- Dimensions according to ISO 7425-2.
- Short axial assembly
- Installation in closed and undercut
- Additional sizes of machined products available on short
Range of application
Mainly used for sealing cylinders in mobile hydraulics.
Operating pressure ≤ 500 bar
Pressure peaks ≤ 1000 bar
Operating temperature -35 °C to +110 °C
Sliding speed ≤ 0.5 m/s
Media Hydraulic oils based on mineral oil
The compound Ultrathan® P5008 is a Parker Praedifa material based on polyurethane with a Shore A hardness of approx. 93.
Back-up ring compound: W5019
The seals should have an axial clearance (see columns H and L). To avoid damage at the sealing lips, the seals should not be pulled over sharp edges during installation. Normally these seals may be snapped into closed grooves. Where access is restricted special assembly tools may be required. Proposals for the design of such tools will be provided on request. For gap sizes see chapter “Maximum Gap Allowance”.