Overview
SIST ISO 3601-5:2016 - "Fluid power systems - O-rings - Part 5: Specification of elastomeric materials for industrial applications" specifies a selection of commonly used elastomeric (rubber) materials for O‑rings in general industrial and fluid‑power applications. The standard lists material types, typical curing systems, required physical properties, and the test methods used to verify suitability. It is intended to help manufacturers, purchasers and designers qualify and inspect standard O‑ring materials while noting that additional compounds may be used by agreement.
Key topics and technical requirements
- Scope of materials: common elastomers covered include NBR (sulfur and peroxide cured), HNBR, FKM, VMQ (silicone), EPDM, and ACM - with typical nominal hardnesses listed in Table 1.
- Curing systems: explains vulcanization and identifies sulfur (S) and peroxide (P) curing as common systems and that not all curing systems suit every elastomer.
- Measured properties (examples from the tables):
- Hardness (IRHD) - specified tolerances for sheet and O‑ring specimens (see ISO 48).
- Tensile strength and elongation at break - minimum values for sheet and O‑ring specimens (ISO 37, ASTM D1414).
- Compression set - maximum limits for specified durations and temperatures (ISO 815‑1, Method A), with different limits by material and cross‑section size.
- Heat ageing - allowable hardness and strength changes after defined heat‑age tests (ISO 188).
- Fluid immersion - volume and hardness change limits after exposure to ISO oils (ISO 1817).
- Low‑temperature flexibility (TR10) - cold retraction limits (ISO 2921).
- Test methods and specimen types: normative references include ISO 37, ISO 48, ISO 188, ISO 815‑1, ISO 1817, ISO 2921 and ISO 3601‑1; either sheet or O‑ring specimens are acceptable for qualification.
- Designations & identification: the standard includes a designation system and identification statement for clear material specification.
- Qualification guidance: Annex A provides informative details on O‑ring stress/strain and compression set testing.
Practical applications and users
Who uses SIST ISO 3601-5:2016:
- O‑ring and elastomer manufacturers for product specification and quality control.
- Hydraulic/pneumatic equipment designers and OEMs to select compatible sealing materials.
- Maintenance engineers and purchasers to define acceptance criteria for incoming O‑rings.
- Test laboratories and quality inspectors for establishing test protocols and lot acceptance frequency.
Typical applications:
- Sealing elements in pumps, valves, cylinders, actuators and general industrial fluid‑power systems where material compatibility with fluid, temperature and pressure must be demonstrated.
Note: The standard specifies common materials and limits, but the final selection of material properties and test methods should be agreed between the equipment manufacturer/user and the O‑ring supplier.
Related standards
Keywords: SIST ISO 3601-5:2016, O‑ring materials, elastomeric materials, fluid power seals, compression set, hardness IRHD, O‑ring specification, material compatibility.