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Seals · Metric O-Rings

Metric O-Rings (ISO 3601)

11 catalogued sizes, dimensioned to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). Pick any row and the technical drawing redraws to it.

Metric O-Rings (ISO 3601) to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections): the full dimensional table is reproduced below. 11 sizes are held in the table below, and the technical drawing redraws to whichever row you select.

Standard
ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections)
Catalogued sizes
11

Dimensions are nominal values from the governing standard. Confirm the tolerance class for your application before ordering.

Metric O-Rings (ISO 3601) technical product image

Applications & Industries

Where Metric O-Rings are used, and what decides the specification in each case. Stocked from 1.0 to 6.0 (inside diameter).

Industries that specify Metric O-Rings

  • Hydraulics Port, cover and piston seals.
  • Pneumatics Cylinder and valve seals.
  • Food and beverage EPDM and silicone compounds.
  • Chemical plant FKM for aggressive media.
  • Hydraulics & pneumatics Static and dynamic sealing in cylinders and valve bodies.
  • Process & food equipment Sealing at joints that are cleaned and inspected.

Typical applications

  • specifying inside diameter, cross-section and compound together
  • matching the compound to the fluid and the temperature
  • checking the groove dimensions give the right squeeze
  • using a back-up ring at high pressure
  • sealing a joint against fluid or air pressure
  • excluding dust and moisture from a housing

Service conditions to specify against

Sealed joints
Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.

Where to use something else

  • Do not substitute an NBR ring for an FKM one because the dimensions match; the size fits and the compound fails, which looks like a leak with no cause.

Full application guide: where Metric O-Rings are used, how to specify them, and the cases they are wrong for

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

Request a Quotation for Metric O-Rings (ISO 3601)

The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

Request a Quotation

Specification
Business Information

Dimensions & Specifications (ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections))

Every row below is a starting point for the customizer above — pick any size and the drawing will redraw to that row.

Cross-section (mm)Typical inside-diameter range (mm)Common compoundsNotes
1.01.0 u2013 20NBR, FKM, EPDM, siliconeminiature and pneumatic
1.52.0 u2013 40NBR, FKM, EPDM, siliconesmall pneumatic and instrument
1.781.78 u2013 50NBR, FKM, EPDMnearest metric equivalent to the 1/16 in section
2.03.0 u2013 100NBR, FKM, EPDM, siliconegeneral hydraulic and pneumatic
2.55.0 u2013 150NBR, FKM, EPDMgeneral hydraulic
3.06.0 u2013 200NBR, FKM, EPDMgeneral hydraulic
3.510 u2013 250NBR, FKMhydraulic
4.012 u2013 300NBR, FKMhydraulic and larger flanges
5.020 u2013 400NBR, FKMlarge flanges and covers
5.3320 u2013 400NBR, FKMnearest metric equivalent to the 3/16 in section
6.025 u2013 500NBR, FKMlarge covers and housings

Metric O-Rings (ISO 3601) are seals manufactured to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). This page lists the full dimensional range with the key specifications engineers need to select and specify them.

What Are Metric O-Rings (ISO 3601)?

Metric O-Rings (ISO 3601) are seals defined by ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). They are selected by inside diameter and the dimensional characteristics shown below, and are available in a range of materials and finishes to suit the application and environment.

Materials & Finishes

O-rings and seals are specified by elastomer, not by steel grade: NBR (nitrile) for mineral oil and hydraulic service, FKM for higher temperature and aggressive chemistry, EPDM for water, steam and weathering, silicone for a wide temperature range in static duty, and PTFE where chemical resistance outweighs elastic recovery. Specify the compound, the hardness in Shore A and the temperature range alongside the dimensions.

Specification Guides

Each size, material and standard of Metric O-Rings (ISO 3601) has its own reference page with the figures for that one configuration.

Goes With

Hardware commonly specified alongside Metric O-Rings (ISO 3601).

Pricing

Metric O-Rings (ISO 3601) are supplied to order. Pricing starts from approximately US$0.050 per piece for standard sizes in standard nitrile (NBR) 70 Shore A; final pricing depends on size, material, finish and order quantity (MOQ applies). Submit your exact configuration with the quote form above.

Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

Which standard governs Metric O-Rings (ISO 3601)?

Metric O-Rings (ISO 3601) are manufactured to ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections). The dimensional values on this page follow that standard.

Which sizes of Metric O-Rings (ISO 3601) does Engineering Hardware supply?

The table on this page lists 11 sizes for Metric O-Rings (ISO 3601), ranging from 1.0 to 6.0. Sizes outside the table can be quoted on request.

In which materials are Metric O-Rings (ISO 3601) supplied?

Metric O-Rings (ISO 3601) are supplied in NBR (nitrile), FKM, EPDM, silicone and PTFE, selected by fluid and temperature, with finishes including zinc plating, hot-dip galvanizing and black oxide. Choose material and finish to suit the load and the service environment for Metric O-Rings (ISO 3601).

How do I request a quotation?

Use the parametric drawing on this page to set the exact configuration (size, material, finish) and click "Request this configuration" — a specialist from Engineering Hardware will respond within one business day.