EN 3050:2025

Aerospace series - O-rings, in fluorocarbon rubber (FKM), low compression set - Technical specification

This document specifies the characteristics, qualification and acceptance requirements for O-rings in low compression set fluorocarbon rubber (FKM) to EN 2798.

Luft- und Raumfahrt - O-Ringe aus Fluorcarbon-Elastomer (FKM) mit niedrigem Druckverformungsrest - Technische Lieferbedingungen

Série aérospatiale - Joints toriques, en élastomère fluorocarbone (FKM), à faible déformation rémanente après compression - Spécification technique

Le présent document spécifie les caractéristiques, et les exigences de qualification et de réception des joints toriques en élastomère fluorocarbone (FKM), à faible déformation rémanente après compression, conformes à l’EN 2798..

Aeronavtika - Tesnilni obročki O, izdelani iz fluoroogljikove gume (FKM) z nizko stopnjo kompresije - Tehnična specifikacija

General Information

• Status: Not Published
• Publication Date: 23-Dec-2025
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3/S 3 - Hydraulics
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Start Date: 29-Sep-2025
• Completion Date: 29-Sep-2025
• Ref Project: kSIST FprEN 3050:2025 - Aerospace series - O-rings, in fluorocarbon rubber (FKM), low compression set - Technical specification

Relations

• Revises: EN 3050:1998 - Aerospace series - O-rings, in fluorocarbon rubber (FKM), low compression set - Technical specification
• Effective Date: 08-Apr-2024

Overview

EN 3050:2025 - "Aerospace series - O-rings, in fluorocarbon rubber (FKM), low compression set - Technical specification" (CEN) defines the characteristics, qualification and acceptance requirements for O-rings made from low compression set FKM in accordance with EN 2798. The standard targets aerospace fluid-system components and sets test, sampling and packaging rules to ensure consistent performance of FKM O-rings in demanding aerospace environments.

Key topics and technical requirements

• Materials and scope
  • O-rings in low compression set fluorocarbon rubber (FKM) as referenced to EN 2798.
• Quality assurance and qualification
  • Manufacturer must be an approved aerospace production organisation and maintain an aerospace quality management system (e.g., EN 9100).
  • Qualification testing on representative sample sizes (e.g., 30 O-rings for two specified sizes).
• Physical and performance tests
  • Hardness: 80 IRHD (ISO 48-2) with specified tolerances.
  • Density: measured per ISO 2781 and EN 2798.
  • Compression set: maximum 25% after 24 h at 200 °C and 55% after 336 h at 200 °C (ASTM D1414).
  • Heat ageing: limited change in hardness after 70 h at 250 °C (ISO 188).
  • Resistance to liquids: defined limits for hardness and volume change after immersion (ISO 1817), including tests at ambient and elevated temperatures.
  • Surface condition: acceptance criteria per ISO 3601-3; 100% visual inspection for packaging.
• Sampling and acceptance
  • Sampling plans for dimensional, visual and physical characteristics are specified (tables for batch sizes, acceptance numbers and AQL).
  • Test reports with numerical values are required for each rubber compound batch.
• Packaging and identification
  • Individual, opaque, water/vapour/ozone/oil/grease-proof packaging (PVC prohibited).
  • Specific package sizes and marking requirements (manufacturer ID, product ID, lot, vulcanization quarter/year, “UNLIMITED SHELF LIFE”, “DO NOT BEND”).

Practical applications and users

• Who uses this standard
  • Aerospace O-ring manufacturers, seal suppliers, procurement and quality assurance teams, OEM design engineers and maintenance/repair organizations.
• Why it matters
  • Ensures traceable, certified FKM O-rings with controlled hardness, compression set and chemical/thermal resistance - critical for fluid systems, hydraulic seals and safety-critical aerospace sealing applications.
• Benefits
  • Consistent product acceptance criteria, harmonized testing and sampling, and clarified packaging/identification to support supply-chain reliability and regulatory compliance.

Related standards

• EN 2798 - Fluorocarbon rubber (FKM) - Low compression set
• ISO 48-2 - Hardness (IRHD)
• ISO 188 - Accelerated ageing
• ISO 1817 - Effect of liquids
• ISO 2781 - Density
• ISO 3601-3 - O-ring quality acceptance
• ISO 27996 - Elastomer seals - Storage and shelf life
• EN 9100 - Aerospace quality management
• ASTM D1414 - Rubber O‑ring test methods

Keywords: EN 3050, O-rings FKM, fluorocarbon rubber, low compression set, aerospace seals, compression set requirements, O-ring qualification, packaging and marking.

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 3050:2024
01-september-2024
Aeronavtika - Tesnilni obročki O, izdelani iz fluoroogljikove gume (FKM) z nizko
stopnjo kompresije - Tehnična specifikacija
Aerospace series - O-rings, in fluorocarbon rubber (FKM), low compression set -
Technical specification
Luft- und Raumfahrt - O-Ringe aus Fluorcarbon-Elastomer (FKM) mit niedrigem
Druckverformungsrest - Technische Lieferbedingungen
Série aérospatiale - Joints toriques, en élastomère fluorocarbone (FKM), à faible
déformation rémanente après compression - Spécification technique
Ta slovenski standard je istoveten z: prEN 3050
ICS:
49.080 Letalski in vesoljski Aerospace fluid systems and
hidravlični sistemi in deli components
oSIST prEN 3050:2024 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 3050:2024
oSIST prEN 3050:2024
DRAFT
EUROPEAN STANDARD
prEN 3050
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2024
ICS 49.080 Will supersede EN 3050:1998
English Version
Aerospace series - O-rings, in fluorocarbon rubber (FKM),
low compression set - Technical specification
Série aérospatiale - Joints toriques, en élastomère Luft- und Raumfahrt - O-Ringe aus Fluorcarbon-
fluorocarbone (FKM), à faible déformation rémanente Elastomer (FKM) mit niedrigem Druckverformungsrest
après compression - Spécification technique - Technische Lieferbedingungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 3050:2024 E
worldwide for CEN national Members.

oSIST prEN 3050:2024
prEN 3050:2024 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Quality assurance . 5
4.1 Qualification . 5
4.1.1 General. 5
4.1.2 Hardness Test . 5
4.2 Acceptance. 5
4.2.1 Conditions . 5
4.2.2 Responsibility . 6
4.2.3 Inspection and test report . 6
5 Requirements . 6
Annex A (normative) Packaging . 9
Bibliography . 11
oSIST prEN 3050:2024
prEN 3050:2024 (E)
European foreword
This document (prEN 3050:2024) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 3050:1998.
prEN 3050:2024 includes the following significant technical changes with respect to EN 3050:1998:
— normative references were updated;
— Subclause 4.1.1 was updated to include further information on qualification;
— Subclause 4.1.2, Hardness Test, was added;
— Bibliography was added.
oSIST prEN 3050:2024
prEN 3050:2024 (E)
1 Scope
This document specifies the characteristics, qualification and acceptance requirements for O-rings in
low compression set fluorocarbon rubber (FKM) to EN 2798.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 2798, Aerospace series — Fluorocarbon rubber (FKM) — Low compressions set — Hardness 80 IRHD
ISO 48-2, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: Hardness between
10 IRHD and 100 IRHD
ISO 188, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
ISO 1817, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 2781, Rubber, vulcanized or thermoplastic — Determination of density
ISO 3601-3, Fluid power systems — O-rings — Part 3: Quality acceptance criteria
ISO 27996, Aerospace fluid systems — Elastomer seals — Storage and shelf life
ASTM D1414, Standard Test Methods for Rubber O-Rings
3 Terms and definitions
For the purposes of this document, the following terms and definiti
...