The Ultimate O-Ring Selection Guide: Insights from the Dichtomatik Handbook

O-rings are among the most versatile and widely used sealing components in industrial, automotive, aerospace, and hydraulic applications. Selecting the right O-ring is critical to ensuring leak-free performance, longevity, and system reliability. Drawing on principles from the Dichtomatik O-Ring Handbook by All Seals Inc., this guide provides engineers and maintenance professionals with actionable insights for optimal O-ring selection and application.

Why O-Ring Material Matters

The performance of an O-ring largely depends on its material compatibility with the operating environment. Common elastomers include:

• Nitrile (NBR): Ideal for oils and fuels; cost-effective for general-purpose use.
• FKM (Viton®): Excellent resistance to high temperatures and aggressive chemicals.
• EPDM: Best for steam, water, and brake fluids—but not for petroleum-based fluids.
• Silicone: Flexible at low temperatures; used in food, medical, and high-temp applications.
• PTFE (Teflon®): Chemically inert and suitable for extreme purity or corrosive environments.

Pro Tip: Always cross-reference your fluid type, temperature range, and pressure conditions with an elastomer compatibility chart—like those in the Dichtomatik Handbook—to avoid premature seal failure.

Nitrile O-Rings (NBR / Buna-N)

Nitrile is widely regarded as the standard choice for oil-based systems and remains one of the best O-ring materials for industrial applications.

NBR is commonly used where O-ring material compatibility with oil and fuel is required. Its balance of performance and cost makes it ideal for general-purpose sealing.

• Temperature range: -40°C to +120°C
• Best applications: Hydraulic systems, pumps, compressors
• Limitations: Poor resistance to ozone and UV exposure

For many engineers comparing nitrile vs viton O-rings, NBR is often selected when temperatures are moderate and cost efficiency is important.

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Viton® O-Rings (FKM)

Viton is a high-performance elastomer designed for harsh environments. It is often considered the best O-ring material for high temperature and chemical resistance.

FKM O-rings provide excellent sealing in aggressive media, making them ideal for petrochemical and chemical processing equipment.

• Temperature range: -20°C to +200°C
• Best applications: Oil and gas industry, chemical processing, vacuum systems
• Limitations: Not suitable for ketones such as acetone

When evaluating viton vs nitrile O-ring comparison, Viton is the preferred option for high-temperature and chemically aggressive conditions.

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EPDM O-Rings (Ethylene Propylene)

EPDM is the preferred elastomer for water-based and outdoor sealing. It offers excellent resistance to ozone, UV, and weathering.

EPDM O-rings are commonly selected as O-ring materials for water and steam applications, especially in HVAC and outdoor systems.

• Temperature range: -55°C to +150°C
• Best applications: Water systems, steam lines, HVAC equipment
• Limitations: Not compatible with petroleum oils or fuels

Engineers often compare EPDM vs nitrile O-rings when selecting seals for non-oil environments.

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Silicone O-Rings (VMQ)

Silicone O-rings are known for flexibility and thermal stability. They are often used where low temperature O-ring materials or FDA compliance is required.

Silicone is commonly selected for clean environments rather than high-pressure systems.

• Temperature range: -60°C to +225°C
• Best applications: Food and beverage, medical devices, electronics
• Limitations: Low tear resistance in dynamic applications

In silicone vs viton O-ring evaluations, silicone is chosen for flexibility and cleanliness, while Viton excels in chemical resistance.

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O-Ring Material Comparison Overview

Material	Oil Resistance	Heat Resistance	Low Temperature	Cost
Nitrile (NBR)	Excellent	Moderate	Good	$
Viton (FKM)	Outstanding	Excellent	Fair	$$$
EPDM	Poor	Good	Excellent	$$
Silicone	Poor	Excellent	Outstanding	$$

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Understanding O-Ring Hardness and Durometer Selection

Material type alone is not enough. Proper O-ring hardness selection is essential, especially for high-pressure systems.

• 70 Shore A: Standard choice for most sealing applications
• 90 Shore A: Recommended for high-pressure or extrusion-prone environments

Incorrect durometer selection is a common cause of leakage and early seal failure.

Read More : How to Select the Right Seal Material for Oil, Gas & Chemical Industries

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Common O-Ring Failure Causes and Troubleshooting

Understanding why O-rings fail prematurely can help prevent future issues:

• Swelling: Caused by chemical incompatibility
• Cracking or hardening: Often due to UV or ozone exposure
• Compression set: Result of excessive heat or long-term compression

Selecting the correct material and hardness greatly reduces these risks.

Correct O-Ring Sizing and Tolerances

An improperly sized O-ring can lead to extrusion, leakage, or excessive friction. Key dimensions include:

• Inside Diameter (ID)
• Cross-Section (CS)
• Groove dimensions (width and depth)

The Dichtomatik Handbook emphasizes proper gland design to ensure:

• Adequate compression (typically 15–30% for static seals, 10–20% for dynamic)
• Sufficient space to prevent over-compression
• Clearance to avoid extrusion under pressure

Use standardized sizing (e.g., AS568, ISO 3601) and consult tolerance tables to match hardware specifications.

Installation Best Practices

Even the highest-quality O-ring can fail if installed incorrectly. Follow these guidelines:

1. Lubricate the O-ring and mating surfaces with a compatible lubricant.
2. Avoid sharp edges on glands or shafts that could nick or tear the seal.
3. Stretch minimally during installation—excessive stretching causes permanent set.
4. Use installation tools for small or tight-tolerance applications to prevent twisting.

The Dichtomatik Handbook includes detailed diagrams and torque recommendations to support safe handling.

Common Failure Modes & How to Prevent Them

Understanding O-ring failure is key to improving system reliability. Typical issues include:

• Extrusion/Nibbling: Caused by high pressure and insufficient gland support. Use backup rings or harder durometer materials.
• Compression Set: Results from prolonged exposure to high temps. Switch to high-temp elastomers like FKM or FFKM.
• Chemical Degradation: Swelling, cracking, or hardening due to fluid incompatibility. Re-evaluate material choice.
• Abrasion: Common in dynamic seals. Ensure proper lubrication and surface finish (Ra < 0.4 µm recommended).

O-rings are fundamental components in countless mechanical systems, providing reliable and efficient sealing solutions. Among the various standards, the Inch Series O-rings, often defined by standards like AS568 (Aerospace Standard) and SAE J2077, hold significant importance, particularly in North American and other industries adhering to imperial measurements.

What Are Inch Series O-Rings?

Inch Series O-rings are standardized elastomeric seals characterized by their cross-sectional diameter (thickness) and inside diameter (ID), both measured in inches (or fractions thereof). Unlike metric O-rings which use millimeters, the dimensions of Inch Series O-rings follow specific charts established by standards organizations. This standardization ensures interchangeability and simplifies the selection process for engineers and maintenance professionals.

What Defines Metric Series O-Rings?

Unlike their inch-based counterparts, Metric Series O-rings are specified using the metric system for both their Inside Diameter (ID) and Cross-Sectional Diameter (CS). This straightforward metric sizing makes them incredibly intuitive for engineers and technicians working within the metric framework. You’ll often find them simply designated by their dimensions, for example, “O-Ring 10 x 2” (ID 10mm, CS 2mm).

How to Prevent O-Ring Failure: A Practical Material Selection Guide for Industrial Systems

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Frequently Asked Questions (FAQ)

What is the best O-ring material for oil and fuel applications?

Nitrile (NBR) is the most common choice due to excellent oil resistance. For higher temperatures or aggressive fuels, Viton (FKM) is recommended.

What is the best O-ring material for high temperature?

Viton and Silicone are both suitable high-temperature O-ring materials. Viton offers superior chemical resistance, while silicone performs better at extreme temperature swings.

Can EPDM O-rings be used with oil?

No. EPDM is not compatible with petroleum-based oils and should only be used in water, steam, or outdoor applications.

How do I choose the correct O-ring hardness?

For most applications, 70 Shore A is sufficient. High-pressure systems may require 90 Shore A O-rings to prevent extrusion.

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Selecting the correct O-ring involves understanding the specific requirements of your application:

Dimensions: Determine the required Inside Diameter (ID) and Cross-Section (CS) based on your groove dimensions. Referencing the AS568 chart is common for inch sizes.
Material: Choose the appropriate elastomer based on the operating temperature, pressure, and the media (fluids, gases) it will contact.
Operating Conditions: Consider factors like pressure cycling, abrasion, and whether the application is static or dynamic (involve movement).
Whether you’re designing a new system or replacing a seal, understanding the role and specifications of Inch Series O-rings is vital for achieving optimal performance and longevity. Their proven track record, standardization, and material diversity make them indispensable elements in achieving reliable sealing across numerous industries.

Size Ref.	Inside Diameter	Tolerance +/-	Cross Section	Tolerance +/-	I.D. MM	Section MM	Volume Cu. Inch	Nominal I.D.	Nominal O.D.	Nominal Width
-001	0.029	0.006	0.040	0.003	0,74	1,02	0.0003	1/32	3/32	1/32
-002	0.042	0.006	0.050	0.003	1,07	1,27	0.0006	3/64	9/64	3/64
-003	0.056	0.006	0.060	0.003	1,42	1,53	0.0010	1/16	3/16	1/16
-004	0.070	0.006	0.070	0.003	1,78	1,78	0.0017	5/64	13/16	1/16
-005	0.101	0.006	0.070	0.003	2,57	1,78	0.0021	3/32	7/32	1/16
-006	0.114	0.006	0.070	0.003	2,90	1,78	0.0022	1/8	1/4	1/16
-007	0.145	0.006	0.070	0.003	3,69	1,78	0.0026	5/32	9/32	1/16
-008	0.176	0.006	0.070	0.003	4,47	1,78	0.0030	3/16	5/16	1/16
-009	0.208	0.006	0.070	0.003	5,28	1,78	0.0034	7/32	11/32	1/16
-010	0.239	0.007	0.070	0.003	6,07	1,78	0.0037	1/4	3/8	1/16
-011	0.239	0.007	0.070	0.003	7,66	1,78	0.0045	5/16	7/16	1/16
-012	0.301	0.007	0.070	0.003	9,25	1,78	0.0052	3/8	1/2	1/16
-013	0.426	0.007	0.070	0.003	10,82	1,78	0.0060	7/16	9/16	1/16
-014	0.489	0.007	0.070	0.003	12,42	1,78	0.0068	1/2	5/8	1/16
-015	0.551	0.007	0.070	0.003	14,00	1,78	0.0075	9/16	11/16	1/16
-016	0.614	0.009	0.070	0.003	15,60	1,78	0.0083	5/8	3/4	1/16
-017	0.676	0.009	0.070	0.003	17,16	1,78	0.0090	11/16	13/16	1/16
-018	0.739	0.009	0.070	0.003	18,77	1,78	0.0098	3/4	7/8	1/16
-019	0.801	0.009	0.070	0.003	20,35	1,78	0.0105	13/16	15/16	1/16
-020	0.864	0.009	0.070	0.003	21,95	1,78	0.0113	7/8	1	1/16
-021	0.926	0.009	0.070	0.003	23,52	1,78	0.0120	15/16	1 1/16	1/16
-022	0.989	0.010	0.070	0.003	25,12	1,78	0.0128	1	1 1/8	1/16
-023	1.051	0.010	0.070	0.003	26,70	1,78	0.0136	1 1/16	1 3/16	1/16
-024	1.114	0.010	0.070	0.003	28,30	1,78	0.0143	1 1/8	1 1/4	1/16
-025	1.176	0.011	0.070	0.003	29,87	1,78	0.0151	1 3/16	1 5/16	1/16
-026	1.239	0.011	0.070	0.003	31,47	1,78	0.0158	1 1/4	1 3/8	1/16
-027	1.301	0.011	0.070	0.003	33,05	1,78	0.0166	1 5/16	1 7/16	1/16
-028	1.364	0.013	0.070	0.003	34,65	1,78	0.0173	1 3/8	1 1/2	1/16
-029	1.489	0.013	0.070	0.003	37,82	1,78	0.0188	1 1/2	1 5/8	1/16
-030	1.614	0.013	0.070	0.003	41,06	1,78	0.0204	1 5/8	1 3/4	1/16
-031	1.739	0.015	0.070	0.003	44,17	1,78	0.0219	1 3/4	1 7/8	1/16
-032	1.864	0.015	0.070	0.003	47,37	1,78	0.0234	1 7/8	2	1/16
-033	1.989	0.018	0.070	0.003	50,52	1,78	0.0249	2	2 1/8	1/16
-034	2.114	0.018	0.070	0.003	53,67	1,78	0.0264	2 1/8	2 1/4	1/16
-035	2.239	0.018	0.070	0.003	56,87	1,78	0.0279	2 1/4	2 3/8	1/16
-036	2.364	0.018	0.070	0.003	60,04	1,78	0.0294	2 3/8	2 1/2	1/16
-037	2.489	0.018	0.070	0.003	63,22	1,78	0.0309	2 1/2	2 5/8	1/16
-038	2.614	0.020	0.070	0.003	66,50	1,78	0.0324	2 5/8	2 3/4	1/16
-039	2.739	0.020	0.070	0.003	69,57	1,78	0.0340	2 3/4	2 7/8	1/16
-040	2.864	0.020	0.070	0.003	72,76	1,78	0.0355	2 7/8	3	1/16
-041	2.989	0.024	0.070	0.003	75,94	1,78	0.0370	3	3 1/4	1/16
-042	3.239	0.024	0.070	0.003	82,28	1,78	0.0400	3 1/4	3 1/2	1/16
-043	3.489	0.024	0.070	0.003	88,64	1,78	0.0430	3 1/2	3 3/4	1/16
-044	3.739	0.027	0.070	0.003	95,12	1,78	0.0460	3 3/4	3 7/8	1/16
-045	3.989	0.027	0.070	0.003	101,34	1,78	0.0491	4	4 1/8	1/16
-046	4.239	0.030	0.070	0.003	107,84	1,78	0.0521	4 1/4	4 3/8	1/16
-047	4.489	0.030	0.070	0.003	114,20	1,78	0.0551	4 1/2	4 5/8	1/16
-048	4.739	0.030	0.070	0.003	120,56	1,78	0.0581	4 3/4	4 7/8	1/16
-049	4.989	0.037	0.070	0.003	126,92	1,78	0.0612	5	5 1/4	1/16
-050	0.049	0.037	0.070	0.003	133,28	1,78	0.0643	1/16	5 3/8	1/16
-102	0.081	0.006	0.103	0.003	1,24	2,62	0.0040	3/32	9/32	3/32
-103	0.112	0.006	0.103	0.003	2,06	2,62	0.0048	2,84	5/16	3/32
-104	0.143	0.006	0.103	0.003	3,63	2,62	0.0064	5/32	11/32	3/32
-105	0.174	0.006	0.103	0.003	4,42	2,62	0.0072	3/16	3/8	3/32
-106	0.206	0.006	0.103	0.003	5,23	2,62	0.0080	7/32	13/32	3/32
-107	0.237	0.007	0.103	0.003	6,02	2,62	0.0088	1/4	7/16	3/32
-108	0.299	0.007	0.103	0.003	7,60	2,62	0.0105	5/16	1/2	3/32
-109	0.362	0.007	0.103	0.003	9,19	2,62	0.0122	3/8	9/16	3/32
-110	0.424	0.007	0.103	0.003	10,78	2,62	0.0138	7/16	5/8	3/32
-111	0.487	0.007	0.103	0.003	12,37	2,62	0.0154	1/2	11/16	3/32
-112	0.549	0.007	0.103	0.003	13,95	2,62	0.0171	9/16	3/4	3/32
-113	0.612	0.007	0.103	0.003	15,54	2,62	0.0187	5/8	13/16	3/32
-114	0.674	0.009	0.103	0.003	17,13	2,62	0.0203	11/16	7/8	3/32
-115	0.737	0.009	0.103	0.003	18,72	2,62	0.0220	3/4	15/16	3/32
-116	0.799	0.009	0.103	0.003	20,29	2,62	0.0236	13/16	1	3/32
-117	0.862	0.010	0.103	0.003	21,90	2,62	0.0253	7/8	1 1/16	3/32
-118	0.924	0.010	0.103	0.003	23,47	2,62	0.0269	15/16	1 1/8	3/32
-119	0.987	0.010	0.103	0.003	25,07	2,62	0.0285	1	1 3/16	3/32
-120	1.049	0.010	0.103	0.003	26,65	2,62	0.0302	1 1/16	1 1/4	3/32
-121	1.112	0.010	0.103	0.003	28,25	2,62	0.0318	1 1/8	1 5/16	3/32
-122	1.174	0.010	0.103	0.003	29,83	2,62	0.0334	1 3/16	1 3/8	3/32
-123	1.237	0.012	0.103	0.003	31,42	2,62	0.0351	1 1/4	1 7/16	3/32
-124	1.299	0.012	0.103	0.003	33,05	2,62	0.0367	1 5/16	1 1/2	3/32
-125	1.362	0.012	0.103	0.003	34,60	2,62	0.0383	1 3/8	1 9/16	3/32
-126	1.424	0.012	0.103	0.003	36,17	2,62	0.0400	1 7/16	1 5/8	3/32
-127	1.487	0.012	0.103	0.003	37,77	2,62	0.0416	1 1/2	1 11/16	3/32
-128	1.549	0.012	0.103	0.003	39,35	2,62	0.0432	1 9/16	1 3/4	3/32
-129	1.612	0.015	0.103	0.003	40,95	2,62	0.0449	1 5/8	1 13/16	3/32
-130	1.674	0.015	0.103	0.003	42,52	2,62	0.0465	1 11/16	1 7/8	3/32
-131	1.737	0.015	0.103	0.003	44,12	2,62	0.0482	1 3/4	1 15/16	3/32
-132	1.799	0.015	0.103	0.003	45,70	2,62	0.0498	1 13/16	2	3/32
-133	1.862	0.015	0.103	0.003	47,30	2,62	0.0514	1 7/8	2 1/16	3/32
-134	1.925	0.015	0.103	0.003	48,90	2,62	0.0531	1 15/16	2 1/8	3/32
-135	1.987	0.017	0.103	0.003	50,47	2,62	0.0547	2	2 3/16	3/32
-136	2.050	0.017	0.103	0.003	52,07	2,62	0.0564	2 1/16	2 1/4	3/32
-137	2.112	0.017	0.103	0.003	53,65	2,62	0.0580	2 1/8	2 5/16	3/32
-138	2.175	0.017	0.103	0.003	55,25	2,62	0.0596	2 3/16	2 3/8	3/32
-139	2.237	0.017	0.103	0.003	56,82	2,62	0.0612	2 1/4	2 7/16	3/32
-140	2.300	0.017	0.103	0.003	58,42	2,62	0.0629	2 5/16	2 1/2	3/32
-141	2.362	0.020	0.103	0.003	60,09	2,62	0.0645	2 3/8	2 9/16	3/32
-142	2.425	0.020	0.103	0.003	61,60	2,62	0.0662	2 7/16	2 5/8	3/32
-143	2.487	0.020	0.103	0.003	63,17	2,62	0.0678	2 1/2	2 11/16	3/32
-144	2.550	0.020	0.103	0.003	64,77	2,62	0.0694	2 9/16	2 3/4	3/32
-145	2.612	0.020	0.103	0.003	66,35	2,62	0.0711	2 5/8	2 13/16	3/32
-146	2.675	0.020	0.103	0.003	67,95	2,62	0.0727	2 11/16	2 7/8	3/32
-147	2.737	0.022	0.103	0.003	69,52	2,62	0.0743	2 3/4	2 15/16	3/32
-148	2.800	0.022	0.103	0.003	71,12	2,62	0.0760	2 7/8	3	3/32
-149	2.862	0.022	0.103	0.003	72,70	2,62	0.0776	2 15/16	3 1/8	3/32
-150	2.987	0.022	0.103	0.003	75,88	2,62	0.0809	3	3 3/16	3/32
-151	3.237	0.024	0.103	0.003	82,22	2,62	0.0874	3 1/4	3 7/16	3/32
-152	3.487	0.024	0.103	0.003	88,58	2,62	0.0940	3 1/2	3 11/16	3/32
-153	3.737	0.024	0.103	0.003	94,93	2,62	0.1005	3 3/4	3 15/16	3/32
-154	3.987	0.028	0.103	0.003	101,28	2,62	0.1071	4	4 3/16	3/32
-155	4.237	0.028	0.103	0.003	107,63	2,62	0.1136	4 1/4	4 7/16	3/32
-156	4.487	0.030	0.103	0.003	113,98	2,62	0.1202	4 1/2	4 11/16	3/32
-157	4.737	0.030	0.103	0.003	120,33	2,62	0.1267	4 3/4	4 15/16	3/32
-158	4.987	0.035	0.103	0.003	126,67	2,62	0.1332	5	5 3/16	3/32
-159	5.237	0.035	0.103	0.003	133,23	2,62	0.1398	5 1/4	5 7/16	3/32
-160	5.487	0.035	0.103	0.003	139,38	2,62	0.1463	5 1/2	5 11/16	3/32
-161	5.737	0.035	0.103	0.003	145,73	2,62	0.1529	5 3/4	5 15/16	3/32
-162	5.987	0.035	0.103	0.003	152,07	2,62	0.1594	6	6 3/16	3/32
-163	6.237	0.040	0.103	0.003	158,43	2,62	0.1660	6 1/4	6 7/16	3/32
-164	6.487	0.040	0.103	0.003	164,78	2,62	0.1726	6 1/2	6 11/16	3/32
-165	6.737	0.040	0.103	0.003	171,13	2,62	0.1791	6 3/4	6 15/16	3/32
-166	6.987	0.040	0.103	0.003	177,48	2,62	0.1856	7	7 3/16	3/32
-167	7.237	0.045	0.103	0.003	183,83	2,62	0.1921	7 1/4	7 7/16	3/32
-168	7.487	0.045	0.103	0.003	190,18	2,62	0.1986	7 1/2	7 11/16	3/32
-169	7.737	0.045	0.103	0.003	196,53	2,62	0.2052	7 3/4	7 15/16	3/32
-170	7.987	0.045	0.103	0.003	202,88	2,62	0.2117	8	8 3/16	3/32
-171	8.237	0.050	0.103	0.003	209,23	2,62	0.2182	8 1/4	8 7/16	3/32
-172	8.487	0.050	0.103	0.003	215,58	2,62	0.2247	8 1/2	8 11/16	3/32
-173	8.737	0.050	0.103	0.003	221,93	2,62	0.2313	8 3/4	8 15/16	3/32
-174	8.987	0.050	0.103	0.003	228,28	2,62	0.2378	9	9 3/16	3/32
-175	9.237	0.055	0.103	0.003	234,63	2,62	0.2443	9 1/4	9 7/16	3/32
-176	9.487	0.055	0.103	0.003	240,98	2,62	0.2508	9 1/2	9 11/16	3/32
-177	9.737	0.055	0.103	0.003	247,33	2,62	0.2574	9 3/4	9 15/16	3/32
-178	0.171	0.006	0.139	0.004	4,34	3,53	0.0148	3/16	7/16	1/8
-201	0.234	0.007	0.139	0.004	5,94	3,53	0.0178	1/4	1/2	1/8
-202	0.296	0.007	0.139	0.004	7,52	3,53	0.0207	5/16	9/16	1/8
-203	0.359	0.007	0.139	0.004	9,12	3,53	0.0237	3/8	5/8	1/8
-204	0.421	0.007	0.139	0.004	10,69	3,53	0.0267	7/16	11/16	1/8
-205	0.484	0.007	0.139	0.004	12,29	3,53	0.0297	1/2	3/4	1/8
-206	0.546	0.007	0.139	0.004	13,87	3,53	0.0327	9/16	13/16	1/8
-207	0.609	0.009	0.139	0.004	15,47	3,53	0.0357	5/8	7/8	1/8
-208	0.671	0.009	0.139	0.004	17,04	3,53	0.0386	11/16	15/16	1/8
-209	0.734	0.010	0.139	0.004	18,64	3,53	0.0416	3/4	1	1/8
-210	0.796	0.010	0.139	0.004	20,22	3,53	0.0446	13/16	1 1/16	1/8
-211	0.859	0.010	0.139	0.004	21,82	3,53	0.0476	7/8	1 1/8	1/8
-212	0.921	0.010	0.139	0.004	23,43	3,53	0.0505	15/16	1 3/16	1/8
-213	0.984	0.010	0.139	0.004	25,03	3,53	0.0535	1	1 1/4	1/8
-214	1.046	0.010	0.139	0.004	26,57	3,53	0.0565	1 1/16	1 5/16	1/8
-215	1.109	0.012	0.139	0.004	28,17	3,53	0.0595	1 1/8	1 3/8	1/8
-216	1.171	0.012	0.139	0.004	29,75	3,53	0.0624	1 3/16	1 7/16	1/8
-217	1.234	0.012	0.139	0.004	31,34	3,53	0.0656	1 1/4	1 1/2	1/8
-218	1.296	0.012	0.139	0.004	32,93	3,53	0.0684	1 5/16	1 9/16	1/8
-219	1.359	0.012	0.139	0.004	34,52	3,53	0.0714	1 3/8	1 5/8	1/8
-220	1.421	0.012	0.139	0.004	36,15	3,53	0.0744	1 7/16	1 11/16	1/8
-221	1.484	0.012	0.139	0.004	37,75	3,53	0.0774	1 1/2	1 3/4	1/8
-222	1.609	0.015	0.139	0.004	40,87	3,53	0.0833	1 5/8	1 7/8	1/8
-223	1.734	0.015	0.139	0.004	44,05	3,53	0.0893	1 3/4	2	1/8
-224	1.859	0.015	0.139	0.004	47,23	3,53	0.0952	1 7/8	2 1/8	1/8
-225	1.984	0.018	0.139	0.004	50,47	3,53	0.1012	2	2 1/4	1/8
-226	2.109	0.018	0.139	0.004	53,57	3,53	0.1072	2 1/8	2 3/8	1/8
-227	2.234	0.018	0.139	0.004	56,75	3,53	0.1131	2 1/4	2 1/2	1/8
-228	2.359	0.020	0.139	0.004	59,92	3,53	0.1191	2 3/8	2 5/8	1/8
-229	2.484	0.020	0.139	0.004	63,19	3,53	0.1250	2 1/2	2 3/4	1/8
-230	2.609	0.020	0.139	0.004	66,27	3,53	0.1310	2 5/8	2 7/8	1/8
-231	2.734	0.024	0.139	0.004	69,44	3,53	0.1370	2 3/4	3	1/8
-232	2.859	0.024	0.139	0.004	72,62	3,53	0.1429	2 7/8	3 1/8	1/8
-233	2.984	0.024	0.139	0.004	75,91	3,53	0.1489	3	3 1/4	1/8
-234	3.109	0.024	0.139	0.004	78,97	3,53	0.1548	3 1/8	3 3/8	1/8
-235	3.234	0.024	0.139	0.004	82,14	3,53	0.1608	3 1/4	3 1/2	1/8
-236	3.359	0.024	0.139	0.004	85,32	3,53	0.1668	3 3/8	3 5/8	1/8
-237	3.484	0.024	0.139	0.004	88,63	3,53	0.1727	3 1/2	3 3/4	1/8
-238	3.609	0.028	0.139	0.004	91,67	3,53	0.1787	3 5/8	3 7/8	1/8
-239	3.734	0.028	0.139	0.004	94,84	3,53	0.1846	3 3/4	4	1/8
-240	3.859	0.028	0.139	0.004	98,02	3,53	0.1906	3 7/8	4 1/8	1/8
-241	3.984	0.028	0.139	0.004	101,35	3,53	0.1966	4	4 1/4	1/8
-242	4.109	0.028	0.139	0.004	104,37	3,53	0.2025	4 1/8	4 3/8	1/8
-243	4.234	0.030	0.139	0.004	107,54	3,53	0.2085	4 1/4	4 1/2	1/8
-244	4.359	0.030	0.139	0.004	110,72	3,53	0.2144	4 3/8	4 5/8	1/8
-245	4.484	0.030	0.139	0.004	114,07	3,53	0.2204	4 1/2	4 3/4	1/8
-246	4.609	0.030	0.139	0.004	117,07	3,53	0.2264	4 5/8	4 7/8	1/8
-247	4.734	0.030	0.139	0.004	120,24	3,53	0.2323	4 3/4	5	1/8
-248	4.859	0.035	0.139	0.004	123,42	3,53	0.2383	4 7/8	5 1/8	1/8
-249	4.984	0.035	0.139	0.004	126,79	3,53	0.2442	5	5 1/4	1/8
-250	5.109	0.035	0.139	0.004	129,77	3,53	0.2502	5 1/8	5 3/8	1/8
-251	5.234	0.035	0.139	0.004	133,15	3,53	0.2561	5 1/4	5 1/2	1/8
-252	5.359	0.035	0.139	0.004	136,33	3,53	0.2621	5 3/8	5 5/8	1/8
-253	5.484	0.035	0.139	0.004	139,51	3,53	0.2681	5 1/2	5 3/4	1/8
-254	5.609	0.035	0.139	0.004	142,69	3,53	0.2740	5 5/8	5 7/8	1/8
-255	5.734	0.035	0.139	0.004	145,87	3,53	0.2800	5 3/4	6	1/8
-256	5.859	0.035	0.139	0.004	149,05	3,53	0.2859	5 7/8	6 1/8	1/8
-257	5.984	0.035	0.139	0.004	152,23	3,53	0.2919	6	6 1/4	1/8
-258	6.234	0.040	0.139	0.004	158,59	3,53	0.3038	6 1/4	6 1/2	1/8
-259	6.484	0.040	0.139	0.004	164,95	3,53	0.3157	6 1/2	6 3/4	1/8
-260	6.734	0.040	0.139	0.004	171,31	3,53	0.3276	6 3/4	7	1/8
-261	6.984	0.040	0.139	0.004	177,67	3,53	0.3396	7	7 1/4	1/8
-262	7.234	0.045	0.139	0.004	184,03	3,53	0.3515	7 1/4	7 1/2	1/8
-263	7.484	0.045	0.139	0.004	190,39	3,53	0.3634	7 1/2	7 3/4	1/8
-264	7.734	0.045	0.139	0.004	196,75	3,53	0.3753	7 3/4	8	1/8
-265	7.984	0.045	0.139	0.004	203,11	3,53	0.3872	8	8 1/4	1/8
-266	8.234	0.045	0.139	0.004	209,47	3,53	0.3992	8 1/4	8 1/2	1/8
-267	8.484	0.045	0.139	0.004	215,83	3,53	0.4117	8 1/2	8 3/4	1/8
-268	8.734	0.050	0.139	0.004	222,19	3,53	0.4230	8 3/4	9	1/8
-269	8.984	0.050	0.139	0.004	228,55	3,53	0.4349	9	9 1/4	1/8
-270	9.234	0.050	0.139	0.004	234,91	3,53	0.4468	9 1/4	9 1/2	1/8
-271	9.484	0.050	0.139	0.004	241,27	3,53	0.4588	9 1/2	9 3/4	1/8
-272	9.734	0.055	0.139	0.004	247,63	3,53	0.4707	9 3/4	10	1/8
-273	9.984	0.055	0.139	0.004	253,99	3,53	0.4826	10	10 1/4	1/8
-274	10.484	0.055	0.139	0.004	266,71	3,53	0.5064	10 1/2	10 3/4	1/8
-275	10.984	0.055	0.139	0.004	279,43	3,53	0.5303	11	11 1/4	1/8
-276	11.484	0.055	0.139	0.004	292,15	3,53	0.5541	11 1/2	11 3/4	1/8
-277	11.984	0.065	0.139	0.004	304,87	3,53	0.5779	12	12 1/4	1/8
-278	12.984	0.065	0.139	0.004	330,31	3,53	0.6256	13	13 1/4	1/8
-279	13.984	0.065	0.139	0.004	355,75	3,53	0.6733	14	14 1/4	1/8
-280	14.984	0.065	0.139	0.004	381,19	3,53	0.7210	15	15 1/4	1/8
-281	15.955	0.065	0.139	0.004	405,90	3,53	0.7676	16	16 1/4	1/8
-282	16.955	0.075	0.139	0.004	431,34	3,53	0.8155	17	17 1/4	1/8
-283	17.955	0.080	0.139	0.004	456,78	3,53	0.8627	18	18 1/4	1/8
-284	0.412	0.085	0.139	0.004	10,48	3,53	0.0677	7/16	13/16	3/16
-309	0.475	0.007	0.21	0.004	12,08	3,53	0.0745	1/2	7/8	3/16
-310	0.537	0.007	0.21	0.004	13,66	3,53	0.0813	9/16	15/16	3/16
-311	0.600	0.009	0.21	0.004	15,26	3,53	0.0881	5/8	1	3/16
-312	0.662	0.009	0.21	0.004	16,84	3,53	0.0949	11/16	1 1/16	3/16
-313	0.725	0.009	0.21	0.004	18,44	3,53	0.1017	3/4	1 1/8	3/16
-314	0.787	0.009	0.21	0.004	20,02	3,53	0.1085	13/16	1 3/16	3/16
-315	0.850	0.009	0.21	0.004	21,62	3,53	0.1153	7/8	1 1/4	3/16
-316	0.912	0.009	0.21	0.004	23,20	3,53	0.1221	15/16	1 5/16	3/16
-317	0.975	0.010	0.21	0.004	24,80	3,53	0.1289	1	1 3/8	3/16
-318	1.037	0.010	0.21	0.004	26,38	3,53	0.1357	1 1/16	1 7/16	3/16
-319	1.100	0.010	0.21	0.004	27,98	3,53	0.1425	1 1/8	1 1/2	3/16
-320	1.162	0.011	0.21	0.004	29,56	3,53	0.1493	1 3/16	1 9/16	3/16
-321	1.225	0.011	0.21	0.004	31,16	3,53	0.1561	1 1/4	1 5/8	3/16
-322	1.287	0.011	0.21	0.004	32,74	3,53	0.1629	1 5/16	1 11/16	3/16
-323	1.350	0.011	0.21	0.004	34,34	3,53	0.1697	1 3/8	1 3/4	3/16
-324	1.475	0.011	0.21	0.004	37,52	3,53	0.1833	1 1/2	1 7/8	3/16
-325	1.600	0.015	0.21	0.004	47,70	3,53	0.1970	1 5/8	2	3/16
-326	1.725	0.015	0.21	0.004	43,88	3,53	0.2106	1 3/4	2 1/8	3/16
-327	1.850	0.015	0.21	0.004	47,06	3,53	0.2242	1 7/8	2 1/4	3/16
-328	1.975	0.015	0.21	0.004	50,24	3,53	0.2378	2	2 3/8	3/16
-329	2.100	0.018	0.21	0.004	53,42	3,53	0.2514	2 1/8	2 1/2	3/16
-330	2.225	0.018	0.21	0.004	56,60	3,53	0.2650	2 1/4	2 5/8	3/16
-331	2.350	0.018	0.21	0.004	59,78	3,53	0.2786	2 3/8	2 3/4	3/16
-332	2.475	0.018	0.21	0.004	62,96	3,53	0.2922	2 1/2	2 7/8	3/16
-333	2.600	0.020	0.21	0.004	66,14	3,53	0.3058	2 5/8	3	3/16
-334	2.725	0.020	0.21	0.004	69,32	3,53	0.3194	2 3/4	3 1/8	3/16
-335	2.850	0.020	0.21	0.004	72,50	3,53	0.3330	2 7/8	3 1/4	3/16
-336	2.975	0.020	0.21	0.004	75,68	3,53	0.3466	3	3 3/8	3/16
-337	3.100	0.024	0.21	0.004	78,86	3,53	0.3602	3 1/8	3 1/2	3/16
-338	3.225	0.024	0.21	0.004	82,04	3,53	0.3738	3 1/4	3 5/8	3/16
-339	3.350	0.024	0.21	0.004	85,22	3,53	0.3874	3 3/8	3 3/4	3/16
-340	3.475	0.024	0.21	0.004	88,40	3,53	0.4010	3 1/2	4	3/16
-341	3.600	0.024	0.21	0.004	91,58	3,53	0.4146	3 5/8	4 1/8	3/16
-342	3.725	0.028	0.21	0.004	94,76	3,53	0.4282	3 3/4	4 1/4	3/16
-343	3.850	0.028	0.21	0.004	97,94	3,53	0.4418	3 7/8	4 3/8	3/16
-344	3.975	0.028	0.21	0.004	101,12	3,53	0.4558	4	4 1/2	3/16
-345	4.100	0.028	0.21	0.004	104,30	3,53	0.4690	4 1/8	4 5/8	3/16
-346	4.225	0.030	0.21	0.004	107,48	3,53	0.4826	4 1/4	4 3/4	3/16
-347	4.350	0.030	0.21	0.004	110,66	3,53	0.4962	4 3/8	4 7/8	3/16
-348	4.475	0.030	0.21	0.004	113,84	3,53	0.5098	4 1/2	5	3/16
-349	4.600	0.030	0.21	0.004	117,02	3,53	0.5243	4 5/8	5 1/8	3/16
-350	4.725	0.030	0.21	0.004	120,20	3,53	0.5379	4 3/4	5 1/4	3/16
-351	4.850	0.030	0.21	0.004	123,38	3,53	0.5515	4 7/8	5 3/8	3/16
-352	4.975	0.037	0.21	0.004	126,56	3,53	0.5652	5	5 1/2	3/16
-353	5.100	0.037	0.21	0.004	129,74	3,53	0.5788	5 1/8	5 5/8	3/16
-354	5.225	0.037	0.21	0.004	132,92	3,53	0.5924	5 1/4	5 3/4	3/16
-355	5.350	0.037	0.21	0.004	136,10	3,53	0.6060	5 3/8	5 7/8	3/16
-356	5.475	0.037	0.21	0.004	139,28	3,53	0.6197	5 1/2	6	3/16
-357	5.600	0.037	0.21	0.004	142,46	3,53	0.6333	5 5/8	6 1/8	3/16
-358	5.725	0.037	0.21	0.004	145,64	3,53	0.6469	5 3/4	6 1/4	3/16
-359	5.850	0.037	0.21	0.004	148,82	3,53	0.6605	5 7/8	6 3/8	3/16
-360	5.975	0.037	0.21	0.004	152,00	3,53	0.6742	6	6 1/2	3/16
-361	6.225	0.037	0.21	0.004	158,36	3,53	0.7014	6 1/4	6 5/8	3/16
-362	6.475	0.040	0.21	0.004	164,72	3,53	0.7287	6 1/2	6 7/8	3/16
-363	6.725	0.040	0.21	0.004	171,08	3,53	0.7559	6 3/4	7 1/8	3/16
-364	6.975	0.040	0.21	0.004	177,44	3,53	0.7832	7	7 3/8	3/16
-365	7.225	0.045	0.21	0.004	183,80	3,53	0.8104	7 1/4	7 5/8	3/16
-366	7.475	0.045	0.21	0.004	190,16	3,53	0.8379	7 1/2	7 7/8	3/16
-367	7.725	0.045	0.21	0.004	196,52	3,53	0.8649	7 3/4	8 1/8	3/16
-368	7.975	0.045	0.21	0.004	202,88	3,53	0.8922	8	8 3/8	3/16
-369	8.225	0.050	0.21	0.004	209,24	3,53	0.9194	8 1/4	8 5/8	3/16
-370	8.475	0.050	0.21	0.004	215,60	3,53	0.9467	8 1/2	8 7/8	3/16
-371	8.725	0.050	0.21	0.004	221,96	3,53	0.9739	8 3/4	9 1/8	3/16
-372	8.975	0.050	0.21	0.004	228,32	3,53	1.0011	9	9 3/8	3/16
-373	9.225	0.055	0.21	0.004	234,68	3,53	1.0284	9 1/4	9 5/8	3/16
-374	9.475	0.055	0.21	0.004	241,04	3,53	1.0557	9 1/2	9 7/8	3/16
-425	4.475	0.033	0.275	0.006	113,84	6,99	0.8863	4 1/2	5	1/4
-426	4.600	0.033	0.275	0.006	117,02	6,99	0.9079	4 5/8	5 1/8	1/4
-427	4.725	0.033	0.275	0.006	120,20	6,99	0.9330	4 3/4	5 1/4	1/4
-428	4.850	0.033	0.275	0.006	123,38	6,99	0.9563	4 7/8	5 3/8	1/4
-429	4.975	0.037	0.275	0.006	126,56	6,99	0.9796	5	5 1/2	1/4
-430	5.100	0.037	0.275	0.006	129,74	6,99	1.0030	5 1/8	5 5/8	1/4
-431	5.225	0.037	0.275	0.006	132,92	6,99	1.0263	5 1/4	5 3/4	1/4
-432	5.350	0.037	0.275	0.006	136,10	6,99	1.0496	5 3/8	5 7/8	1/4
-433	5.475	0.037	0.275	0.006	139,28	6,99	1.0729	5 1/2	6	1/4
-434	5.600	0.037	0.275	0.006	142,46	6,99	1.0962	5 5/8	6 1/8	1/4
-435	5.725	0.037	0.275	0.006	145,64	6,99	1.1196	5 3/4	6 1/4	1/4
-436	5.850	0.037	0.275	0.006	148,82	6,99	1.1429	5 7/8	6 3/8	1/4
-437	5.975	0.037	0.275	0.006	152,00	6,99	1.1662	6	6 1/2	1/4
-438	6.225	0.037	0.275	0.006	158,36	6,99	1.2129	6 1/4	6 3/4	1/4
-439	6.475	0.040	0.275	0.006	164,72	6,99	1.2595	6 1/2	7	1/4
-440	6.725	0.040	0.275	0.006	171,08	6,99	1.3062	6 3/4	7 1/4	1/4
-441	6.975	0.040	0.275	0.006	177,44	6,99	1.3528	7	7 1/2	1/4
-442	7.225	0.045	0.275	0.006	183,80	6,99	1.3995	7 1/4	7 3/4	1/4
-443	7.475	0.045	0.275	0.006	190,16	6,99	1.4461	7 1/2	8	1/4
-444	7.725	0.045	0.275	0.006	196,52	6,99	1.4928	7 3/4	8 1/4	1/4
-445	7.975	0.045	0.275	0.006	202,88	6,99	1.5394	8	8 1/2	1/4
-446	8.475	0.045	0.275	0.006	215,60	6,99	1.6327	8 1/2	9	1/4
-447	8.975	0.055	0.275	0.006	228,32	6,99	1.7260	9	9 1/2	1/4
-448	9.475	0.055	0.275	0.006	241,04	6,99	1.8193	9 1/2	10	1/4
-449	9.975	0.055	0.275	0.006	253,76	6,99	1.9126	10	10 1/2	1/4
-450	10.475	0.060	0.275	0.006	266,48	6,99	2.0059	10 1/2	11	1/4
-451	10.975	0.060	0.275	0.006	279,20	6,99	2.0992	11	11 1/2	1/4
-452	11.475	0.060	0.275	0.006	291,20	6,99	2.1925	11 1/2	12	1/4
-453	11.975	0.060	0.275	0.006	304,64	6,99	2.2858	12	12 1/2	1/4
-454	12.475	0.060	0.275	0.006	317,36	6,99	2.3791	12 1/2	13	1/4
-455	12.975	0.060	0.275	0.006	330,08	6,99	2.4724	13	13 1/2	1/4
-456	13.475	0.070	0.275	0.006	342,80	6,99	2.5657	13 1/2	14	1/4
-457	13.975	0.070	0.275	0.006	355,52	6,99	2.6590	14	14 1/2	1/4
-458	14.475	0.070	0.275	0.006	368,24	6,99	2.7523	14 1/2	15	1/4
-459	14.975	0.070	0.275	0.006	380,96	6,99	2.8456	15	15 1/2	1/4
-460	15.475	0.070	0.275	0.006	393,68	6,99	2.9389	15 1/2	16	1/4
-461	15.955	0.075	0.275	0.006	405,90	6,99	3.0350	16	16 1/2	1/4
-462	16.455	0.075	0.275	0.006	418,62	6,99	3.1285	16 1/2	17	1/4
-463	16.955	0.080	0.275	0.006	431,34	6,99	3.2220	17	17 1/2	1/4
-464	17.455	0.085	0.275	0.006	444,06	6,99	3.3155	17 1/2	18	1/4
-465	17.955	0.085	0.275	0.006	456,78	6,99	3.4090	18	18 1/2	1/4
-466	18.455	0.085	0.275	0.006	469,50	6,99	3.5025	18 1/2	19 1/4	1/4
-467	18.955	0.090	0.275	0.006	482,22	6,99	3.5960	19	19 1/2	1/4
-468	19.455	0.090	0.275	0.006	494,94	6,99	3.6895	19 1/2	20	1/4
-469	19.955	0.095	0.275	0.006	507,66	6,99	3.7830	20	20 1/2	1/4
-470	20.955	0.095	0.275	0.006	533,10	6,99	3.9700	21	21 1/2	1/4

References & Further Reading

• Dichtomatik O-Ring Handbook (PDF)
• ISO 3601 Metric O-Rings – Global O-Ring and Seal
• O-Ring Chemical Compatibility Chart – AllOrings.com
• Chemical Resistance Guide – The O-Ring Store
• Engineer Technical Reference Guide for O-Ring Design – AllOrings.com