Parker O-Ring X-Reference: Sizes, Compounds & Equivalents

Parker Hannifin is one of the largest and most widely referenced suppliers of O-rings and sealing components in the industrial world. Engineers, maintenance teams, and procurement professionals frequently encounter Parker part numbers, compound codes, and dash numbers when specifying or replacing seals. Understanding how to decode these designations — and how to cross-reference them to generic industry standards — is essential for sourcing equivalent O-rings when Parker lead times are long, when cost reduction is required, or when an alternative supplier must be qualified.

Parker O-Ring Numbering System

Parker O-ring part numbers follow a structured format that encodes size, material, and sometimes special features. The most common format is:

2-XXX (size code) + compound suffix

The "2-XXX" Dash Number

The prefix "2-" indicates a standard O-ring. The three-digit number (XXX) is Parker's internal size code, which maps directly to the AS568 dash number system. This is the most important cross-reference to understand: in the vast majority of cases, Parker's 2-XXX number is interchangeable with AS568-XXX.

For example:

Parker 2-214 = AS568-214 = inside diameter 0.984 inch, cross-section 0.139 inch
Parker 2-110 = AS568-110 = inside diameter 0.362 inch, cross-section 0.103 inch
Parker 2-325 = AS568-325 = inside diameter 1.475 inch, cross-section 0.210 inch

This mapping holds for the entire 2-series: 2-001 through 2-475 correspond to AS568-001 through AS568-475. The dimensional tolerances specified by Parker for these sizes are also aligned with AS568 Class 1 (standard) or Class 2 (precision) tolerances.

Metric Sizes

For metric O-rings, Parker uses a different numbering convention. Common metric series include:

2- prefix for inch-series (AS568)
3- prefix for some metric series (depending on catalog)
Direct millimeter specification for custom metric sizes

Metric O-rings are often specified by inside diameter × cross-section in millimeters rather than by dash number. When cross-referencing metric Parker sizes, verify the actual ID and CS dimensions rather than relying on the prefix alone.

Less Common Prefixes

Parker occasionally uses prefixes other than "2-" for specialized O-ring types:

Prefix	Description
2-	Standard molded O-ring, AS568 sizes
3-	Metric or non-AS568 standard sizes (catalog-dependent)
S-	Spliced or vulcanized O-rings (large diameters)
Custom	Special compounds, colors, or formulations

For procurement, always request the dimensional drawing or AS568 dash number when a non-standard prefix is encountered. This prevents ambiguity in manufacturing and inspection.

Parker Dash Number to AS568 Cross-Reference

The following table confirms the direct equivalence between Parker 2-series dash numbers and AS568 dash numbers for the most commonly requested sizes:

Parker Part No.	AS568 Equivalent	Nominal ID (inch)	Nominal CS (inch)	Nominal ID (mm)	Nominal CS (mm)
2-006	−006	0.070	0.070	1.78	1.78
2-007	−007	0.103	0.070	2.62	1.78
2-008	−008	0.112	0.070	2.84	1.78
2-009	−009	0.147	0.070	3.73	1.78
2-010	−010	0.176	0.070	4.47	1.78
2-011	−011	0.239	0.070	6.07	1.78
2-110	−110	0.362	0.103	9.19	2.62
2-111	−111	0.424	0.103	10.77	2.62
2-112	−112	0.487	0.103	12.37	2.62
2-113	−113	0.549	0.103	13.94	2.62
2-114	−114	0.612	0.103	15.54	2.62
2-115	−115	0.674	0.103	17.12	2.62
2-116	−116	0.737	0.103	18.72	2.62
2-117	−117	0.799	0.103	20.29	2.62
2-118	−118	0.862	0.103	21.89	2.62
2-119	−119	0.924	0.103	23.47	2.62
2-120	−120	0.987	0.103	25.07	2.62
2-121	−121	1.049	0.103	26.64	2.62
2-122	−122	1.112	0.103	28.24	2.62
2-123	−123	1.174	0.103	29.82	2.62
2-124	−124	1.237	0.103	31.42	2.62
2-125	−125	1.299	0.103	32.99	2.62
2-126	−126	1.362	0.103	34.59	2.62
2-127	−127	1.424	0.103	36.17	2.62
2-128	−128	1.487	0.103	37.77	2.62
2-129	−129	1.549	0.103	39.34	2.62
2-130	−130	1.612	0.103	40.94	2.62
2-131	−131	1.674	0.103	42.52	2.62
2-132	−132	1.737	0.103	44.12	2.62
2-133	−133	1.799	0.103	45.69	2.62
2-134	−134	1.862	0.103	47.29	2.62
2-135	−135	1.925	0.103	48.90	2.62
2-136	−136	1.987	0.103	50.47	2.62
2-137	−137	2.050	0.103	52.07	2.62
2-138	−138	2.112	0.103	53.64	2.62
2-139	−139	2.175	0.103	55.25	2.62
2-140	−140	2.237	0.103	56.82	2.62
2-141	−141	2.300	0.103	58.42	2.62
2-142	−142	2.362	0.103	59.99	2.62
2-143	−143	2.425	0.103	61.60	2.62
2-144	−144	2.487	0.103	63.17	2.62
2-145	−145	2.550	0.103	64.77	2.62
2-210	−210	0.734	0.139	18.64	3.53
2-211	−211	0.796	0.139	20.22	3.53
2-212	−212	0.859	0.139	21.82	3.53
2-213	−213	0.921	0.139	23.39	3.53
2-214	−214	0.984	0.139	24.99	3.53
2-215	−215	1.046	0.139	26.57	3.53
2-216	−216	1.109	0.139	28.17	3.53
2-217	−217	1.171	0.139	29.74	3.53
2-218	−218	1.234	0.139	31.34	3.53
2-219	−219	1.296	0.139	32.92	3.53
2-220	−220	1.359	0.139	34.52	3.53
2-221	−221	1.421	0.139	36.09	3.53
2-222	−222	1.484	0.139	37.69	3.53
2-223	−223	1.609	0.139	40.87	3.53
2-224	−224	1.734	0.139	44.04	3.53
2-225	−225	1.859	0.139	47.22	3.53
2-226	−226	1.984	0.139	50.39	3.53
2-227	−227	2.109	0.139	53.57	3.53
2-228	−228	2.234	0.139	56.74	3.53
2-229	−229	2.359	0.139	59.92	3.53
2-230	−230	2.484	0.139	63.09	3.53
2-231	−231	2.609	0.139	66.27	3.53
2-232	−232	2.734	0.139	69.44	3.53
2-233	−233	2.859	0.139	72.62	3.53
2-234	−234	2.984	0.139	75.79	3.53
2-235	−235	3.109	0.139	78.97	3.53
2-236	−236	3.234	0.139	82.14	3.53
2-237	−237	3.359	0.139	85.32	3.53
2-238	−238	3.484	0.139	88.49	3.53
2-239	−239	3.609	0.139	91.67	3.53
2-240	−240	3.734	0.139	94.84	3.53
2-325	−325	1.475	0.210	37.47	5.33
2-326	−326	1.600	0.210	40.64	5.33
2-327	−327	1.725	0.210	43.82	5.33
2-328	−328	1.850	0.210	46.99	5.33
2-329	−329	1.975	0.210	50.17	5.33
2-330	−330	2.100	0.210	53.34	5.33
2-331	−331	2.225	0.210	56.52	5.33
2-332	−332	2.350	0.210	59.69	5.33
2-333	−333	2.475	0.210	62.87	5.33
2-334	−334	2.600	0.210	66.04	5.33
2-335	−335	2.725	0.210	69.22	5.33
2-336	−336	2.850	0.210	72.39	5.33
2-337	−337	2.975	0.210	75.57	5.33
2-338	−338	3.100	0.210	78.74	5.33
2-339	−339	3.225	0.210	81.92	5.33
2-340	−340	3.350	0.210	85.09	5.33
2-341	−341	3.475	0.210	88.27	5.33
2-342	−342	3.600	0.210	91.44	5.33
2-343	−343	3.725	0.210	94.62	5.33
2-344	−344	3.850	0.210	97.79	5.33
2-345	−345	3.975	0.210	100.97	5.33
2-346	−346	4.100	0.210	104.14	5.33
2-347	−347	4.225	0.210	107.32	5.33
2-348	−348	4.350	0.210	110.49	5.33
2-349	−349	4.475	0.210	113.67	5.33
2-350	−350	4.600	0.210	116.84	5.33

This is not an exhaustive list — Parker's 2-series covers all AS568 dash numbers from −001 to −475. For sizes not listed here, the mapping is direct: Parker 2-XXX = AS568-XXX.

Dimensional Verification

While the dash number mapping is direct, always verify dimensions when switching suppliers. Manufacturing tolerances, mold tooling, and quality control can produce measurable differences between suppliers even for the same nominal dash number. For critical applications, request a dimensional inspection report (CMM or optical measurement) for the first article.

Parker Compound Codes Decoded

Parker uses alphanumeric compound designations that encode the base polymer and hardness. The first letter indicates the polymer family; the numbers indicate the specific compound formulation; and the trailing number (after the hyphen or as a separate specification) indicates Shore A hardness.

Common Parker Compound Cross-Reference

Parker Compound	Base Polymer	Hardness (Shore A)	Generic Equivalent	Key Properties
N0674-70	NBR (Nitrile)	70	NBR 70	Standard oil-resistant, low cost, −30°C to +100°C
N0674-90	NBR (Nitrile)	90	NBR 90	High hardness for extrusion resistance
N1490-70	NBR (Low-temp)	70	Low-temp NBR	Improved low-temp to −40°C
V0747-75	FKM (Fluorocarbon)	75	FKM 75	High temp, fuel resistant, −15°C to +200°C
V0747-90	FKM (Fluorocarbon)	90	FKM 90	High hardness, high pressure
V1238-80	FKM (GF-type)	80	GF-FKM 80	High fluorine, broader chemical resistance
E0540-70	EPDM	70	EPDM 70	Water, steam, phosphate ester, −40°C to +120°C
E0540-80	EPDM	80	EPDM 80	Higher hardness EPDM
S0604-70	VMQ (Silicone)	70	VMQ 70	Wide temp range, low strength, −60°C to +200°C
S0604-80	VMQ (Silicone)	80	VMQ 80	Higher hardness silicone

Understanding the Compound Code Structure

N = Nitrile (NBR) family
V = Viton/Fluorocarbon (FKM) family
E = EPDM family
S = Silicone (VMQ) family
Numbers (e.g., 0674, 0747) = Internal Parker compound formulation identifier
Trailing number (e.g., −70, −75, −90) = Nominal Shore A hardness

The compound formulation number is proprietary to Parker — it identifies the specific polymer grade, filler package, cure system, and additive package used. Two different compound numbers within the same polymer family (e.g., N0674 vs. N1490) may use different base polymers, different cure chemistry, or different additive packages that produce different physical properties beyond hardness.

Hardness Interpretation

The trailing number is nominal Shore A hardness. Typical tolerances are ±5 Shore A for 70-durometer compounds and ±4 Shore A for 90-durometer compounds. For procurement of equivalent O-rings, match the nominal hardness and verify that the tolerance is acceptable for your application.

Application	Typical Hardness	Rationale
General-purpose static seal	70 Shore A	Good compliance, low seating force
Dynamic seal (reciprocating)	70–80 Shore A	Balanced compliance and wear resistance
High-pressure static seal	80–90 Shore A	Extrusion resistance
High-pressure dynamic seal	85–90 Shore A	Maximum extrusion resistance with acceptable friction
Low-temperature service	70 Shore A	Softer compound maintains flexibility at low temperature

How to Find an Equivalent or Replacement O-Ring

When a Parker part number is specified but Parker supply is unavailable or too expensive, follow this systematic approach to identify an equivalent:

Step 1: Decode the Size

Extract the dash number from the Parker part number. For 2-XXX format, the AS568 equivalent is direct. For metric or non-standard prefixes, request the actual ID and CS dimensions.

Example: Parker 2-214-V0747-75

Size: 2-214 = AS568-214
Material: V0747 = FKM family
Hardness: 75 Shore A

Step 2: Identify the Base Polymer

Match the Parker compound prefix to the generic polymer family:

Parker Prefix	Polymer	Primary Applications
N	NBR	Mineral oils, hydraulic fluids, fuels, water
V	FKM	High temperature, aggressive chemicals, aromatic fuels
E	EPDM	Water, steam, phosphate ester, brake fluid, polar solvents
S	VMQ	Wide temperature, low strength, FDA/food-grade options
P	Polyurethane (PU)	High abrasion, dynamic hydraulics, pneumatics
K	HNBR	Sour gas, automotive AC, high-temp oil service

Notes: PTFE is not a standard one-letter elastomer prefix in Parker O-ring compound numbering; PTFE seals are usually listed by specific product families. FFKM is also not a single standard prefix — Parker uses specialty compound codes (e.g., Parofluor ULTRA series). For PTFE or FFKM equivalents, request the compound data sheet and compare ASTM D2000 or manufacturer specs.

Step 3: Match the Hardness

Specify the equivalent hardness. In most cases, the exact hardness match is required for proper gland fill and squeeze percentage. A 5-point hardness difference changes the effective cross-section by approximately 1–2%, which can be significant in precision gland designs.

Step 4: Verify Critical Physical Properties

For high-performance or critical applications, request the following data from the alternative supplier and compare to Parker specifications:

Property	Test Standard	Typical Requirement
Tensile strength	ASTM D412	≥ 10 MPa (NBR), ≥ 8 MPa (FKM)
Elongation at break	ASTM D412	≥ 150%
Compression set (22 h at standard temp)	ASTM D395	≤ 20% (NBR), ≤ 25% (FKM)
Hardness	ASTM D2240	Match ±5 Shore A
Temperature range	Supplier datasheet	Must cover operating range

Step 5: Verify Fluid Compatibility

If the application involves a specific fluid (particularly hydraulic fluid with additive packages, aviation fuels, or process chemicals), request immersion test data or conduct ASTM D471 immersion testing on samples from the alternative supplier. Do not rely on generic compatibility charts for critical applications — additive packages in commercial fluids can significantly alter compatibility.

Step 6: Qualify the Alternative Supplier

For production quantities, conduct a first-article inspection (FAI) including:

Dimensional verification (ID, CS, tolerances per AS568)
Hardness measurement
Visual inspection (no flash, voids, or surface defects)
Batch test data review (if available)
Functional testing in the actual application or a representative test fixture

Special Considerations for Critical Applications

Aerospace and Defense

Aerospace applications typically require material specifications beyond the generic polymer type. Parker aerospace compounds (e.g., compounds qualified to AMS-R-83485 for FKM, AMS 3216 for NBR) carry specific batch testing and traceability requirements. When cross-referencing aerospace Parker parts, verify that the alternative supplier can provide:

Certificate of Conformance (CoC) referencing the AMS specification
Lot-specific batch test data
Date-of-cure marking per SAE AS 1933
Full material traceability

Generic commercial-grade equivalents are not acceptable for flight-critical hardware.

Food and Pharmaceutical

For FDA 21 CFR 177.2600 applications, Parker specifies compounds with USP Class VI or FDA-compliant formulations. When cross-referencing, verify that the alternative compound is certified to the same regulatory standard — not merely "food-grade" or "FDA acceptable." Request the FDA compliance letter or USP test report.

Semiconductor and Cleanroom

Semiconductor applications require low-outgassing, low-extractable compounds with metal-ion control. Parker compounds for semiconductor service (e.g., specific cleanroom-grade FKM or FFKM formulations) may not have direct generic equivalents. Cross-reference only with suppliers who can provide outgassing test data (per ASTM E595) and metallic contamination analysis.

FAQ

Q1: Is a Parker 2-XXX O-ring exactly the same size as an AS568-XXX O-ring?

Yes, dimensionally they are equivalent. Parker designed the 2-series to map directly to AS568 dash numbers, and the nominal dimensions and tolerances are identical. However, manufacturing variations between suppliers can produce small differences in actual dimensions — typically within the AS568 tolerance band, but potentially at opposite ends of the tolerance range. For critical applications, verify actual dimensions with a first-article inspection when switching suppliers.

Q2: Can I replace a Parker V0747-75 O-ring with a generic FKM 75?

In most industrial applications, yes. V0747-75 is a standard FKM compound at 75 Shore A hardness. A generic FKM 75 Shore A O-ring from a reputable supplier will provide equivalent performance in standard mineral oil, fuel, and chemical service. The exceptions: (1) Aerospace applications requiring AMS-R-83485 qualification — generic FKM may not meet the specification; (2) Applications with specific fluid additive packages where Parker's proprietary formulation provides compatibility advantages; (3) Extreme temperature or chemical environments where a specific high-fluorine FKM grade is required.

Q3: What is the difference between Parker N0674 and N1490?

Both are NBR compounds, but they are formulated for different service conditions. N0674 is the standard general-purpose NBR compound with good oil resistance and mechanical properties for typical industrial hydraulic and pneumatic service. N1490 is a low-temperature NBR formulation with improved cold flexibility — it maintains sealing performance to approximately −40°C versus approximately −30°C for N0674. N1490 is specified for outdoor equipment, cold-climate hydraulics, and applications where startup at low temperature is required. N0674 is lower cost and adequate for normal temperature ranges.

Q4: Can I cross-reference Parker metric O-ring sizes to AS568?

Metric Parker sizes do not map directly to AS568 dash numbers because the dimensions are different. AS568 is an inch-based standard with specific ID and CS values; metric sizes follow ISO 3601-1 or are custom dimensions. A metric O-ring with ID 25.00 mm and CS 3.53 mm is close to AS568-214 (24.99 mm × 3.53 mm) — the difference is 0.01 mm, which is usually negligible. But a metric size like 30.00 mm × 4.00 mm has no direct AS568 equivalent. Always verify actual dimensions rather than assuming interchangeability between metric and inch-based sizes.

Q5: Why does the Parker compound number matter if the polymer and hardness are the same?

The compound number identifies the specific formulation, not just the base polymer and hardness. Different compounds within the same polymer family can have significantly different physical properties: compression set resistance, fluid swell behavior, low-temperature flexibility, and high-temperature stability. For example, two FKM compounds at 75 Shore A may differ in fluorine content (65% vs. 70%), cure system (bis-phenol vs. peroxide), or additive package — producing different chemical resistance and temperature limits. For non-critical applications, the polymer family and hardness are usually sufficient. For critical applications, match the compound number or request detailed physical property data.

Q6: How do I specify an equivalent O-ring when the Parker part number is worn or missing?

If the part number is unreadable, measure the installed O-ring's inside diameter and cross-sectional diameter using calibrated measuring tools (cone gauges for CS, optical comparator or CMM for ID). Identify the application fluid and operating temperature range. With these three pieces of information — dimensions, fluid, and temperature — a qualified supplier can specify the correct AS568 size and material. If the O-ring is still installed in a standard gland (SAE J1926, ISO 3601, etc.), the gland dimensions can also be used to infer the correct O-ring size. Do not guess based on visual appearance alone.

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Need to cross-reference a Parker O-ring or find an equivalent? Contact our engineering team with the Parker part number, compound code, or your measured dimensions and application conditions — we decode the specification, confirm the AS568 equivalent, and supply equivalent O-rings in NBR, FKM, EPDM, and VMQ with dimensional certification and material CoC. Custom compounds and aerospace-grade materials available with full traceability.