ISO 7425-2-2021 PDF

Full title and description

Hydraulic fluid power cylinders — Dimensions and tolerances of housings for elastomer-energized, plastic-faced seals — Part 2: Rod seal housings. This international standard specifies standardised housing dimensions and associated tolerances for rod seal housings intended to accommodate elastomer-energized, plastic-faced seals used in reciprocating hydraulic cylinder applications.

Abstract

This document specifies the dimensions and associated tolerances for a series of hydraulic cylinder rod seal housings to accommodate elastomer-energized, plastic-faced seals used in reciprocating applications. It does not specify seal design, material selection or functional performance of the seals; those are left to seal manufacturers and the application conditions (temperature, pressure, anti-extrusion requirements). The standard applies only to dimensional characteristics and tolerances of housings produced in accordance with the document.

General information

• Status: Published.
• Publication date: 22 February 2021.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 23.100.20 (Cylinders).
• Edition / version: Edition 2 (2021-02).
• Number of pages: 8.

Scope

The standard defines dimensional series and tolerances for rod seal housings so that elastomer-energized, plastic-faced rod seals from different suppliers can be accommodated in hydraulic cylinders designed to these housings. It excludes detailed seal construction, material specifications and functional testing; those aspects are determined by seal manufacturers and application requirements such as operating temperature, pressure and anti-extrusion measures. The document is limited to the dimensional characteristics of housings, not to the functional characteristics of seals or assemblies.

Key topics and requirements

• Standardised nominal housing geometries for rod seal installation.
• Tolerancing requirements for housing dimensions (to ensure interchangeability between seal and cylinder manufacturers).
• Reference dimensions and tolerances for common reciprocating rod-seal arrangements.
• Statement that seal design, materials and anti‑extrusion components are outside the scope and are application-dependent.
• Replacement of the earlier 1989 edition (historic reference and withdrawal of previous edition).

Typical use and users

Used by hydraulic cylinder designers, OEMs, seal manufacturers, component suppliers, engineering purchasers and quality/inspection teams to ensure dimensional compatibility and interchangeability of rod seal housings and seals. Also used by standards committees and technical libraries as a reference for part design and procurement specifications.

Related standards

ISO 7425-1:2021 — Part 1 covers piston seal housings and is the companion document in the same series. The 2021 edition of Part 2 replaces the earlier ISO 7425-2:1989 (withdrawn). Other related hydraulic cylinder and seal standards (e.g., general cylinder dimensions and O‑ring/backup ring standards) are commonly referenced alongside ISO 7425 parts when specifying sealing systems.

Keywords

hydraulic cylinder, rod seal housing, elastomer-energized seal, plastic-faced seal, dimensions, tolerances, interchangeability, ISO 7425, sealing housings.

FAQ

Q: What is this standard?

A: ISO 7425-2:2021 is an international standard that defines dimensions and tolerances for rod seal housings used with elastomer-energized, plastic-faced seals in reciprocating hydraulic cylinders.

Q: What does it cover?

A: It covers the nominal housing configurations and the associated dimensional tolerances required for mechanical interchangeability of rod seals; it does not cover seal material specifications, detailed seal design or functional performance tests.

Q: Who typically uses it?

A: Cylinder designers, seal and component manufacturers, OEMs, procurement and quality-inspection personnel, and standards bodies use it to ensure compatible housing dimensions and to specify parts for manufacture and purchase.

Q: Is it current or superseded?

A: It is the current published edition (Edition 2, published 22 February 2021) and replaced the 1989 edition; the standard is listed as an international standard under systematic review (review activity recorded with ISO). Please consult ISO or your national standards body for the latest status if you need confirmation after 22 February 2021.

Q: Is it part of a series?

A: Yes — it is Part 2 of ISO 7425. Part 1 (ISO 7425-1:2021) covers piston seal housings; the parts together standardise housing dimensions for common elastomer-energized, plastic-faced sealing arrangements in hydraulic cylinders.

Q: What are the key keywords?

A: Hydraulic cylinder, rod seal housing, elastomer-energized, plastic-faced seal, dimensions, tolerances, interchangeability, ISO 7425-2:2021.