What Information Does a Customer Need to Provide for O-Ring Selection

Jul.23.2026

The core is not "asking the customer for a pile of parameters" — it's letting sales and customer service judge three things in the shortest time: can it be quoted quickly as a standard part, is engineering selection needed, and is there an existing failure or compliance risk.

An O-ring's basic dimensions are usually defined by inner diameter d1 and cross-section diameter d2 (also called wire diameter); ISO 3601-1 also organizes the O-ring dimension and tolerance identification code system around inner diameter, cross-section.

One. Minimum Information: Quick Quote Version

When a customer just wants to buy a common O-ring, sales should at minimum get the following 6 items:

Required Field	What the Customer Should Provide	Purpose
Dimension	ID × wire diameter, or OD × wire diameter, or spec number, e.g. AS568, ISO 3601, GB/T 3452, JIS B 2401	Judges whether it's a standard stock spec, whether opening a new mold is needed
Material	NBR, FKM, EPDM, VMQ, HNBR, FFKM etc.; if unknown, state the contacted media	Core basis for material selection
Hardness	Shore A, e.g. 70A, 75A, 80A, 90A; if unknown, state "not sure"	Determines compression deformation, assembly difficulty, extrusion resistance
Media contacted	Oil, water, air, steam, fuel, refrigerant, acid/alkali, solvent, food, pharma liquid etc.	Core basis for material selection
Temperature and pressure	Working temperature, highest/lowest temperature, working pressure, peak pressure	Judges material, hardness, whether a back-up ring is needed
Quantity and lead time	Sample quantity, batch quantity, annual usage quantity, expected delivery time	Quote, inventory, production schedule

These 6 items can support a preliminary quote, but cannot guarantee a correct type selection. O-ring reliability depends on installation groove, compression rate, clearance, motion form, surface roughness, lubrication and pressure direction factors; e.g. extrusion risk under pressure directly correlates with sealing clearance and material hardness, and may need increased hardness or added back-up rings when necessary.

Two. Complete Information: Engineering Selection Version

1. Dimensional Specification Information

Field	Customer Should Provide	Sales Judgment Point
ID	mm or inch	Preferred dimension field
Cross-section CS	mm or inch	Preferred dimension field
Outer diameter OD	Auxiliary provide	OD = ID + 2×CS, can be used for cross-check
Standard number	AS568, ISO 3601, GB/T 3452, JIS B 2401, DIN 3771 etc.	Judges standard library and tolerance system
Tolerance requirement	General, tightened, per drawing	Judges whether custom or inspection control is needed
Whether a sample exists	Yes/No; whether it's an old, deformed, or failed part	An old part's dimension may already be stretched, compressed, or swollen — cannot be treated fully as the design dimension
Whether a drawing exists	2D/3D/groove diagram/assembly diagram	Prioritize drawing review when a drawing exists

Sales judgment rule: when the customer only gives "OD is however much, thickness is however much," must ask back whether it's the free-state dimension or the post-assembly measured dimension. Old O-rings commonly have compression set, swelling, wear, and the measured dimension deviates from the original spec, should not be installed directly per this.

2. Seal Type and Motion Method

Field	Customer Should Provide	Why Important
Static/dynamic seal	Static seal, reciprocating motion, rotary motion, oscillating motion	Determines compression rate, friction, wear and material choice
Installation position	Face seal, axial seal, radial seal, piston seal, rod seal, flange seal, valve-stem seal	Determines groove structure
Motion speed	Reciprocating speed, rotation speed, frequency, stroke	Necessary for a dynamic seal to evaluate friction and wear
Whether lubricated	Dry friction, oil lubrication, water lubrication, grease lubrication	Affects wear, friction and compatibility
Surface material	Metal, plastic, glass, ceramic etc.	Affects wear, friction and compatibility
Surface roughness	Ra value or machining method	Especially critical for high-speed/dynamic seals

O-rings are usually classified by relative-motion type into static seals and dynamic seals: almost no relative motion is a static seal; reciprocating, rotary, or oscillating motion is a dynamic seal. Special attention: although an O-ring can be used for some dynamic applications, dynamic scenarios generally only suit medium operating conditions; higher speed, higher pressure, or long-term wear scenarios may need a dedicated seal member, not a general O-ring.

3. Media Information

Field	Customer Should Provide	Example
Media name	Specific liquid/gas name	Hydraulic oil, water, air, steam, gasoline, diesel, refrigerant, cold-chain fluid, alcoholic, acid/alkali
Media composition	Chemical name, concentration, additive	"30% ethylene glycol water solution + antifreeze" is more useful
Media state	Liquid, gas, steam, powder	Gas/vacuum sealing needs additional consideration of permeation and compression set
Whether mixed media	Multiple media or cleaning agents	Food, medical, chemical, CIP/SIP common
Contact method	Long-term immersion, intermittent contact, splash contact, cleaning contact	Determines material safety margin
Whether ozone/UV/outdoor	Yes/No	Affects EPDM, NBR, CR and other material selection

Material selection cannot just look at broad statements like "oil resistant, high-temperature resistant." Elastomer materials are affected by media, oxygen, ozone, pressure and temperature and other external factors, and may present swelling, shrinkage, hardening, cracking or tearing.

4. Temperature Information

Field	Customer Should Provide	Sales Judgment Point
Normal working temperature	Long-term temperature	Selects the material's primary basis
Highest temperature	Peak temperature	Judges whether short-term overheating is sufficient
Lowest temperature	Cold-startup, low-temperature environment	Judges low-temperature elasticity and embrittlement risk
Temperature duration	Short-term, periodic, long-term	Affects compression set and aging risk
Temperature cycling	Whether hot/cold alternates	Affects compression set and leak risk

Temperature is not an isolated parameter. High temperature will erode the elastomer's chemical resistance, low temperature can cause elasticity loss and form a leak path. So sales cannot only ask "how heat-resistant does it need to be" — should follow up: how much for long-term, how much peak, how long sustained, and whether it cycles hot/cold.

5. Pressure Information

Field	Customer Should Provide	Sales Judgment Point
Working pressure	MPa, bar, psi	Judges whether the common hardness is enough
Peak pressure	Instant highest pressure	Judges pressure-shock and groove design
Pressure direction	One-way, two-way, internal pressure, external pressure	Determines back-up ring position and groove design
Pressure variation	Stable, pulsed, frequent startup	Pressure shock combines with extrusion risk
Whether vacuum	Vacuum degree	Affects gas permeability, compression set, material outgassing risk
Whether high-pressure gas	Helium, air, natural gas etc.	Explosive-decompression relevant, need to note permeation, gas expansion

The higher the pressure, the more you can't just "swap for a harder material." An O-ring's extrusion limit under pressure is jointly determined by the sealing clearance and hardness; if pressure and clearance combined exceed material capability, hardness needs to be raised, clearance reduced, or a back-up ring added.

6. Groove and Installation Structure Information

Field	Customer Should Provide	Why Important
Groove type	Axial groove, radial groove, live-plug groove, rod groove, end-face groove	Determines O-ring compression direction
Groove width	mm	Judges whether expansion space is sufficient
Groove depth	mm	Judges compression rate
Groove ID	Shaft diameter, bore diameter, groove-bottom diameter	Judges stretch rate and compression rate
Fit clearance	Clearance between piston and cylinder, shaft and hole	Affects extrusion risk
Surface roughness	Ra or machining method	Affects sealing lifespan and leakage
Chamfer and assembly path	Whether sharp corners, threads, holes exist	Key for high-pressure scenarios
Whether back-up ring allowed	Single, double back-up ring, not allowed	Determines whether other sealing forms need changing

Groove information decides whether the O-ring "can seal well" and "can seal at all." The O-ring needs to obtain initial sealing capability through compression, while groove depth, clearance, and line diameter jointly determine the compression rate; dynamic seals generally need lower compression to lower friction.

7. Material and Hardness Information

Field	Customer Should Provide	Sales Judgment Point
Specified material	NBR, FKM, EPDM, VMQ, HNBR, FVMQ, FFKM, PTFE encapsulated etc.	Whether it can be priced per customer specification
Hardness	70A, 75A, 80A, 90A etc.	Affects assembly, compression, extrusion resistance
Color	Black, brown, green, red, transparent etc.	Color cannot serve as material basis
Low-temperature requirement	Whether cold-startup, low-temperature seal	Judges NBR/FKM/VMQ/HNBR applicability
Compression set requirement	Whether long-term compression cannot leak	Common in static seal, vacuum, medical, food equipment
Wear resistance requirement	Dynamic seal, frequently moving	Judges whether other seal form is needed
Existing product material	What material currently used, whether failed	Judges replacement, upgrade, or cost reduction

Common material pre-screening can be done this way, but must still recheck with specific media and temperature: general mineral oil/hydraulic oil → NBR, HNBR, FKM (temperature high or life requirement high should preferentially evaluate HNBR/FKM); fuel oil, gasoline, diesel → FKM, FVMQ, FFKM (need to confirm fuel composition, alcohol additives); hot water, steam, ethylene-glycol coolant → EPDM (doesn't fit most petroleum-based oils); food equipment → FDA-related material, VMQ, EPDM, FKM etc., must confirm food-contact regulation and test report; high-temperature chemical media → FKM, FFKM, PTFE-encapsulated, cost difference is large, must confirm specific chemical; low-temperature seal → VMQ, FVMQ, low-temperature NBR, low-temperature FKM, low-temperature elasticity is more critical than room-temperature hardness; high-pressure hydraulic → 90A NBR/FKM/HNBR + back-up ring, need to see pressure, clearance, groove.

8. Certification, Regulatory, and Quality Requirements

Scenario	Customer Should Explain	Sales Should Follow Up
Food contact	FDA, LFGB, EU 1935/2004, 3-A etc.	Is it material compliance or finished-product testing? Is a test report needed?
Drinking water	NSF/ANSI/CAN 61, WRAS, KTW, ACS etc.	Contact water temperature, country/market, certificate valid range
Medical/pharma	USP Class VI, ISO 10993, DMF, extractables/leachables	Is it raw-material screening, component verification, or ultimately medical-device filing?
Automotive	IATF 16949, PPAP, IMDS, RoHS, REACH	Is a PPAP grade, material data, batch traceability needed?
Aerospace/military	AS568, AMS, MIL, full-dimension report	Drawing, spec number, full-dimension report
Environmental compliance	RoHS, REACH, PAHs, halogen, phthalate	Applicable country and customer specification
Batch traceability	COC, COA, material certificate, batch number	Is it required every batch, or is stock kept

Food contact cannot only write "food grade." US FDA 21 CFR 177.2600 specifies material requirements for elastomer products for repeated food contact used in production, processing, packaging, transport or holding of food; drinking water more commonly references the health impact of drink-water system components as specified by NSF/ANSI/CAN 61; medical, USP <88> covers biological reactivity of elastomers, plastics and other polymer materials; ISO 10993-1 is used for risk-management framework for biological evaluation of medical devices; automotive companies commonly require an IATF 16949 quality management system, PPAP, IMDS and customer-specific specifications; AIAG and ISO/TS 16949:2016 explain it defines the quality management system requirements for global automotive industry organizations.

Three. Quick Judgment Process for Pre-Sales and Customer Service

Step One: Judge Whether the Customer Is "Buying a Replacement Part" or "Doing New Design"

Replacement part: priority ask: is there an old part, drawing, spec number, equipment model, current-use material, failure reason. Suits quick quote, but be alert: the old part's dimension may already be deformed, best also provide groove dimension or drawing.

New design: must ask: sealing structure, media, temperature, pressure, motion form, groove, certification, life requirement. A new design cannot only quote per "ID × wire diameter" — otherwise later leak risk is high.

Step Two: First Judge Whether It's a Standard Part or Non-Standard Part

Customer Situation	Sales Action
Customer provides AS568, ISO 3601, GB/T 3452, JIS B 2401 or other spec number	Directly check stock and standard pricing
Customer provides ID × wire diameter	Match standard spec; confirm tolerance if close to a standard dimension
Customer only provides OD	Follow up wire diameter or ID
Customer only sends a photo	Request supplemental dimensions, drawing or sample
Customer provides an old part	Recommend simultaneously measuring the groove, avoid ordering per a deformed dimension
Customer requires a special dimension	Judge whether an existing mold exists; if not, evaluate mold-opening, MOQ, lead time

Step Three: Judge Material Risk

Customer Statement	What's Unclear	Should Follow Up
"Need oil resistance"	Oil type not clear	Hydraulic oil, machine oil, diesel, gasoline, silicone oil, synthetic oil? How much temperature?
"Need high-temperature resistance"	Temperature range not clear	How much long-term? How much peak? How long sustained?
"Need corrosion resistance"	Chemical name unclear	Chemical name, concentration, temperature, whether mixed media?
"Need food-grade"	Standard unclear	FDA, LFGB, 3-A, NSF? Is a report needed?
"Need medical-grade"	Contact grade unclear	Is it human contact? Contact time? Is USP/ISO 10993 needed?
"Need automotive-grade"	Quality-document unclear	Is IATF, PPAP, IMDS, RoHS/REACH needed?

Step Four: Judge Whether Engineering Review Is Needed

When any of the following occurs, sales should not directly promise "this material has no problem" — should transfer to engineering or technical confirmation.

High-Risk Signal	Reason
Dynamic seal, high-speed rotation, frequent reciprocating	O-ring may wear, generate heat, twist
High pressure, pressure pulsation, large clearance	May extrude, cut, need back-up ring or structure change
Steam, strong acid/alkali, solvent, fuel, brake fluid, coolant	Material compatibility risk high
Low-temperature startup or hot/cold cycling	May have low-temperature compression set
Vacuum or gas seal	Need to consider permeation, outgassing, compression set
Food, medical, drink water, automotive, aerospace	Compliance and traceability requirement high
Customer has leak, swelling, cracking, wear issue with existing part	Failure analysis needed, not simply swap the same spec

Four. Directly Usable O-Ring Inquiry Information Sheet

A. Basic Information

Field	Customer to Fill In
Customer name/project name	___
Applied equipment/component name	___
Is it a replacement or new design	Replacement / New design / Not sure
Whether a drawing exists	Yes / No
Whether a sample exists	Yes / No
Whether existing spec/part number exists	___
Expected quantity	Sample: ___ pcs; batch: ___ pcs; annual usage: ___ pcs
Expected lead time	___

B. Dimensional Specification

Field	Customer to Fill In
Inner diameter ID	___ mm/inch
Wire diameter CS	___ mm/inch
Outer diameter OD	___ mm/inch
Standard spec	AS568/ISO 3601/GB/T 3452/JIS B 2401/other
Tolerance requirement	General / tightened / per drawing
Drawing number	___
Whether alternative standard dimensions allowed	Yes / No / need confirmation

C. Operating Condition Information

Field	Customer to Fill In
Seal type	Static seal / dynamic seal
Installation form	Face / axial / radial / live plug / rod / flange / valve stem / other
Motion method	No motion / reciprocating / rotary / oscillating
Motion speed or frequency	___
Whether lubricated	Dry friction / oil lubrication / water lubrication / grease lubrication / not sure
Media	___
Media concentration/formula	___
Working temperature	Normal: ___; lowest: ___; highest: ___
Working pressure	Normal pressure: ___; highest: ___; peak: ___
Whether vacuum	Yes/No; vacuum degree: ___
Whether pressure shock	Yes / No / not sure
Whether outdoor, ozone, UV environment	Yes / No

D. Groove and Structure

Field	Customer to Fill In
Groove width	___ mm
Groove depth	___ mm
Groove-bottom diameter	___ mm
Shaft diameter/bore diameter	___ mm
Fit clearance	___ mm
Pressure direction	One-way / two-way / internal pressure / external pressure
Surface roughness	Ra ___
Whether allows using a fitted drawing	Yes / No / not sure
Whether assembly passes threads, sharp corners, chamfer	Yes / No

E. Material, Hardness, and Certification

Field	Customer to Fill In
Specified material	NBR/FKM/EPDM/VMQ/HNBR/FFKM/other
Specified hardness	___ Shore A
Color requirement	Black/brown/green/red/white/transparent/other
Whether food-grade certification required	FDA/LFGB/3-A/other/not needed
Whether drinking-water certification required	NSF/WRAS/KTW/ACS/other/not needed
Whether medical-grade required	USP Class VI/ISO 10993/other/not needed
Whether automotive-grade required	IATF 16949/PPAP/IMDS/other/not needed
Whether RoHS/REACH required	Yes / No
Whether COC/COA material report required	Yes / No
Whether batch traceability required	Yes / No

F. Existing Product Failure Situation

Field	Customer to Fill In
Existing product material	___
Failure after how long in use	___
Failure phenomenon	Leak / swelling / shrinkage / cracking / hardening / softening / wear / broken / discoloration
Whether failure photo exists	Yes / No
Whether material has been changed	Yes / No
Problem to be solved hopefully	Cost reduction / life extension / oil resistance / prevent leak / certification / other

Five. Simplest Inquiry Script Facing the Customer

Can be sent directly to the customer:

To quickly confirm the O-ring spec, please provide the following information: Dimension: inner diameter × wire diameter, or outer diameter × wire diameter; if a drawing/sample exists please send together. Material and hardness: e.g. NBR 70A, FKM 75A; if not sure please state the contact media. Contact media: oil, water, air, steam, fuel, chemical liquid or food value. Temperature and pressure: long-term working temperature, highest/lowest temperature, working pressure and peak pressure. Installation method: static seal or dynamic seal, if dynamic seal please state rotational or reciprocating motion. Groove/installation: e.g. groove dimension, mating component or equipment model, if available please provide. Certification requirement: is food-grade, medical-grade, drinking-water, automotive-grade, RoHS/REACH etc. needed. Quantity and lead time: sample quantity, batch quantity, expected lead time.

Six. Sales-Internal Field Priority

Priority	Field	No-Time Handling
P0, essential	Dimension, quantity, purpose, media, temperature, pressure	Cannot make a reliable selection, can only do a rough inquiry
P0, essential	Static/dynamic seal	Cannot judge groove, compression rate, friction risk
P1, high-risk essential	Groove dimension, clearance, pressure direction	High pressure, dynamic seal, failure problems must be supplemented
P1, high-risk essential	Certification and report requirement	Food, medical, automotive, drinking water must be confirmed
P1, high-risk essential	Existing product failure information	Must be collected if leaked or damaged already
P2, business essential	Packaging, lead time, annual usage, target price	Used for quoting and supply arrangement

Seven. Most Common Mistakes

Only asking dimension, not asking media. Dimension only decides whether it can be installed — it doesn't decide whether it can hold pressure, is oil resistant, water resistant, or steam/chemical resistant.

Only asking material, not asking temperature. The same material's media-resistance table can differ greatly between room temperature and high temperature.

Only asking pressure, not asking clearance. Whether it extrudes under high pressure doesn't only depend on pressure — it also depends on groove clearance, hardness, and whether there's a back-up ring.

Treating color as material. Black is not necessarily NBR, brown is not necessarily FKM, transparent is not necessarily silicone. Color can only serve as auxiliary information.

Treating "food-grade/medical-grade/automotive-grade" as a single material attribute. This type of requirement is essentially about matching regulation, report, system, traceability, and customer specification — the specific standard must be clarified.

Directly copying the old O-ring dimension. An old part may already be compression-set, stretched, expanded or shrunk — best combine with groove dimension and drawing confirmation.

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What Information Does a Customer Need to Provide for O-Ring Selection

One. Minimum Information: Quick Quote Version

Two. Complete Information: Engineering Selection Version

1. Dimensional Specification Information

2. Seal Type and Motion Method

3. Media Information

4. Temperature Information

5. Pressure Information

6. Groove and Installation Structure Information

7. Material and Hardness Information

8. Certification, Regulatory, and Quality Requirements

Three. Quick Judgment Process for Pre-Sales and Customer Service

Step One: Judge Whether the Customer Is "Buying a Replacement Part" or "Doing New Design"

Step Two: First Judge Whether It's a Standard Part or Non-Standard Part

Step Three: Judge Material Risk

Step Four: Judge Whether Engineering Review Is Needed

Four. Directly Usable O-Ring Inquiry Information Sheet

A. Basic Information

B. Dimensional Specification

C. Operating Condition Information

D. Groove and Structure

E. Material, Hardness, and Certification

F. Existing Product Failure Situation

Five. Simplest Inquiry Script Facing the Customer

Six. Sales-Internal Field Priority

Seven. Most Common Mistakes

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What Information Does a Customer Need to Provide for O-Ring Selection

One. Minimum Information: Quick Quote Version

Two. Complete Information: Engineering Selection Version

1. Dimensional Specification Information

2. Seal Type and Motion Method

3. Media Information

4. Temperature Information

5. Pressure Information

6. Groove and Installation Structure Information

7. Material and Hardness Information

8. Certification, Regulatory, and Quality Requirements

Three. Quick Judgment Process for Pre-Sales and Customer Service

Step One: Judge Whether the Customer Is "Buying a Replacement Part" or "Doing New Design"

Step Two: First Judge Whether It's a Standard Part or Non-Standard Part

Step Three: Judge Material Risk

Step Four: Judge Whether Engineering Review Is Needed

Four. Directly Usable O-Ring Inquiry Information Sheet

A. Basic Information

B. Dimensional Specification

C. Operating Condition Information

D. Groove and Structure

E. Material, Hardness, and Certification

F. Existing Product Failure Situation

Five. Simplest Inquiry Script Facing the Customer

Six. Sales-Internal Field Priority

Seven. Most Common Mistakes

Useful Links

Product

Portfolio