Margo Rubber Products
Oil filler cap O-rings in NBR and FKM
SHORE A
±5 pts
TENSILE
Per compound datasheet, tested to ASTM D412

O-Rings

Oil Filler Cap O-Rings — Moulded to ISO 3601 Sizes

Moulded O-rings for oil filler caps and filler necks — NBR as standard, FKM where the engine runs hot. Supplied to ISO 3601 sizes and AS568 dash numbers, or to your own inside diameter and cross-section, from our plant in Nashik.

HARDNESS
70 Shore A standard, 50–90 available
TEMPERATURE
−30 to +120 °C on NBR; −20 to +250 °C on FKM
INSIDE DIAMETER
To ISO 3601-1, AS568 or your drawing
CROSS-SECTION
1.78–8.40 mm standard range, to ISO 3601-1
TOLERANCE CLASS
ISO 3601-1 Class A or Class B
QTY (pieces)
−10,000+
Minimum run: 10,000 pieces per part number
Request QuoteRequest documentation
  • MADE TO ORDER
  • ISO 9001:2015
  • 09111526A

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Visual Reference

360° PREVIEW

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Cross section viewSection through the ring and its groove — on request

Size code
ISO 3601-1 designation, or AS568 dash number
Groove dimensions
To ISO 3601-2
Squeeze
The compression the groove applies — too little leaks, too much sets
Seal type
Static face seal or radial

Section drawing available on request. Send the ISO 3601 or AS568 size code if you have one — or the groove dimensions, or the old ring with a note of the medium and temperature — and we will confirm size, compound and hardness for approval.

Technical specifications

Engineering Data

Product Family
O-Rings
Material
NBR standard; FKM, silicone or EPDM per medium and temperature
Hardness (Shore A)
70 Shore A standard, 50–90 available
Tensile Strength
Per compound datasheet, ASTM D412
Elongation at Break
Per compound datasheet, ASTM D412
Operating Temperature
−30 to +120 °C on NBR; −20 to +250 °C on FKM — see section 03
Compression Set
Tested to ASTM D395 Method B
Density
Per compound datasheet
Colour Options
Black standard; colour coding by compound on request
Lead Time
Confirmed with the quotation, from approved drawing and approved sample
Inside diameter (d1)
To ISO 3601-1 or your drawing
Cross-section (d2)
1.78–8.40 mm standard range, ISO 3601-1
Tolerance class
ISO 3601-1 Class A or B
Surface quality
ISO 3601-3 acceptance criteria
Certifications
ISO 9001:2015 — certificate 09111526A, valid to 21 February 2027
Minimum Order
10,000 pieces per part number, per compound, or quoted against the part where geometry or tooling makes that unrealistic. Prototype and first-article lots sit outside the minimum.

Dimensional reference

To customer drawing
Size code
ISO 3601-1 designation, or AS568 dash number
Groove dimensions
To ISO 3601-2
Squeeze
The compression the groove applies — too little leaks, too much sets
Seal type
Static face seal or radial

Available materials

Rubber Compound Options

Select the compound best suited to your operating environment and application requirements.

Compound

NBR

Nitrile Butadiene Rubber

Temperature range

−30 to +120 °C

For this part

The standard oil-seal compound and the right default here. Engine oil, oil vapour and blow-by gases at filler-neck temperature.

Not sure? Send the medium, temperature and load

Oil filler cap O-rings in NBR and FKM

SIZE STANDARD

ISO 3601

Class A codes = AS568 dash numbers

Key advantages

Why Specifiers Choose Margo

  • We will tell you when NBR is enough

    FKM costs two to three times NBR and earns it only above +120 °C. Send the measured temperature and we will specify down where we can — on a part ordered in tens of thousands, that is the quote.

  • Compression set is the whole game

    An O-ring seals by being squeezed and springing back. We test compression set in-house to ASTM D395 Method B and report it with every consignment — it is the number that says whether the seal is still a seal in a year.

  • ISO 3601 or AS568, your choice

    Class A size codes are the same as AS568 dash numbers. Send either — or the groove dimensions to ISO 3601-2 and we will size the ring to the housing.

  • A good ring in a bad groove still leaks

    Squeeze too light and it weeps; too heavy and it takes a set. If you are designing the housing, send it to us before you cut it — the check costs nothing and it is where most seal failures start.

Industries served

Global Applications

  • Automotive

    Oil filler caps and necks, cam-cover and dipstick seals, fluid-reservoir caps

  • Heavy Industry

    Hydraulic and pneumatic fittings, gearbox and hydraulic-reservoir caps, static seals on plant

  • Pumps & Valves

    Static O-ring seals are core pump and valve hardware

  • Infrastructure

    Hydraulic fittings on site plant and equipment

Manufacturing process

From Compound to Certification

  1. Material compounding

    Polymer blending, additive integration and batch QC in our in-house lab. Compression set at temperature is set here — it is the property an O-ring lives or dies on.

  2. Mould design and CNC tool manufacture, in-house, held as a controlled record. Multi-cavity tooling

    O-rings are made hundreds at a time.

  3. Compression Moulding

    Hydraulic press cycles at controlled temperature and pressure profiles per product spec.

  4. Post-cure and deflashing

    The parting line is the seal face on an O-ring, so flash removal is the step that decides whether it seals.

  5. Quality inspection

    Inside diameter, cross-section and surface quality checked against ISO 3601-1 and -3, plus hardness and batch sampling.

  6. Export packaging

    Industrial packing with documentation. Bagged by size code so the ring can be identified after delivery. ISPM-15 treated pallets where timber is used.

Quality assurance

Certified to International Standards

Every product leaves our facility with a documentation package — material test reports, dimensional inspection sheets and a certificate of conformance — giving traceability from raw material to finished part.

  • ISO 9001:2015 · Certificate 09111526A

    Integral Certification Ltd · Valid to 21 February 2027

    Scope: rubber moulded components — this part is within scope

  • IATF 16949 — upgrade in progress, certification targeted by end 2026

  • ISO 14001 and ISO 45001 — targeted 2027

O-rings are manufactured to ISO 3601 sizes and tolerances. This is a dimensional standard, not a certification.

Certification detail

Production metrics

Since 2005
In operation
60+
Active clients
3–4 weeks from approved sample
Avg. lead time

Downloads

Technical Documentation

Compound datasheets and dimensioned drawings are issued on request, under NDA where required. Send the ISO 3601 or AS568 size code, or the groove dimensions, and we will confirm the ring against it.

Request the size chart

FAQ

Technical & Commercial Questions

Answers to the most common questions from engineering teams and procurement managers worldwide.

  • What is the minimum order quantity for this part?

    We supply in bulk. The minimum run is 10,000 pieces per part number, per compound, or quoted against the part where geometry or tooling makes that unrealistic. Prototype and first-article lots sit outside the minimum.

  • Can you match a competitor specification or reverse-engineer an existing part?

    Yes. Send the size code if you have one — that is the whole specification. If not, send the old ring, and tell us the medium and temperature: a used O-ring has taken a set and measures smaller than it was moulded, so we size from the groove, not the sample.

  • What file formats do you accept for drawings?

    PDF, DWG and DXF — but for an O-ring a drawing is usually unnecessary. An ISO 3601 designation or AS568 dash number, plus the compound and hardness, is a complete specification. Groove dimensions to ISO 3601-2 if you have them.

  • Do you provide material test reports with each shipment?

    Yes. Material test reports, dimensional inspection sheets and a certificate of conformance ship with every consignment. Hardness, tensile to ASTM D412 and compression set to ASTM D395 Method B are tested in-house, with dimensions and surface quality checked to ISO 3601-1 and -3.

  • What are your payment and delivery terms for international orders?

    TT and LC accepted, discussed per order. Ex-works Nashik or FOB Nhava Sheva. Commercial invoice, packing list and certificate of origin are issued with every consignment. O-rings ship bagged and labelled by size code.

Same compound

Other parts we mould in the same compounds

Need this part quoted?

Send the size code, the groove dimensions, or the old ring with the medium and temperature. We confirm size, compound and hardness — and tell you if a cheaper compound will do — then quote against your annual quantity. We respond within 48 hours.

Request a quoteBack to O-Rings