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» Soft Seal Connectors – The ultimate hydraulic connectors

Soft seal connectors are a modern development in hydraulic connectors, intended to address the most common issues with older designs, including leakage and the effects of vibration.

They’re also designed to work in much higher pressure systems, to meet the growing needs of a wide range of applications across different industries.

Soft Seal Connector Definitions


noun (Chemistry)

An elastic substance occurring naturally, as a natural rubber, or produced synthetically, such as butyl rubber or neoprene.


adjective (Chemistry)

A part that has an elastic quality about it, or one that uses an elastomer.

Soft seal, or elastomeric connectors use a soft seal to complete the joint, resulting in a leak free and vibration resistant joint.

The seal is usually an O-ring.

Advantages of soft seal connectors

Soft seal connectors have a number of advantages, including:

  • They are positive sealing
  • Resistant to vibration
  • Very high pressure capability
  • Easy and quick to assemble, which is important in high-volume production

Disadvantages of soft seal connectors

The O-ring in soft seal connectors may harden with heat or soften with incompatible system fluids, so it is important that the seal material is suitable for the application.

Fluids that can affect the elastic material in soft seal connectors include fuels, oils, solvents and other substances, depending on the composition of the soft seal.

For this reason, selecting the right soft seal connector for the intended application is essential to ensure that the connector continues to perform as expected.

Practical Applications of Soft Seal Connectors

Examine the hydraulic system of this loader.

RYCO Hydraulic Hose Soft Seal Connectors

It has been designed to be leak free. It employs elastomeric sealing with SAE flange, ORFS, UNO ports and O-ring sealing inside the pumps.

It has been in service for a period of time already, and remains clean and leak-free.

Elastomeric couplings are a modern, leak-free alternative to some older design hydraulic couplings.

New hydraulic systems can be designed and sold on the basis of being leak-free.

All it takes is a little understanding of the connection options available.

Soft Seal Connectors In Industry

Soft seal connectors, also called elastomeric connectors, use a soft seal to complete the joint, addressing both leakage and vibration effects.

Types of Soft Seal Connectors

Here are the main types of soft seal connectors available:

  • DKOL (Dicht Kegel O Ring Leicht)
  • DKOS (Dicht Kegel O Ring Schwer)
  • SAE Flange (Society of Automotive Engineers)
  • Quick release couplings
  • BSPP port – British Standard Pipe Parallel
  • UNO port – Unified National O-ring
  • ORFS – O-Ring Face Seal

For an overview of the different hydraulic connector types, check out our introduction to hydraulic connectors.

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