Metric O-Ring Information


Metric O-Rings are a type of mechanical gasket used for sealing applications. They are a specific variation of O-Rings, which are mechanical seals in the shape of a torus with a round cross-section. Metric O-Rings are designed with standardized dimensions based on the International Organization for Standardization or ISO 3601, making them suitable for applications that follow metric specifications.

The sizing of metric O-Rings is defined by their internal dimension (ID) and cross-section (CS). For example, a typical part number for a metric O-Ring would be specified as "CS X ID [material & shore hardness]." For instance, "N2.00X010" denotes an O-Ring with a 2mm cross-section, 10mm cross-section, made from Buna-N Nitrile rubber (NBR) with a shore hardness of 70.

Metric O-Rings are manufactured using various materials, such as synthetic rubbers, thermosets, and elastomers, each chosen based on factors like chemical compatibility, temperature range, sealing pressure, lubrication requirements, durometer, size, and cost. Some of the most common materials used for metric O-Rings include:

  1. Buna-N Nitrile (NBR) Metric O-Rings 70 Durometer: NBR is a popular choice due to its good mechanical properties, resistance to lubricants and greases, and cost-effectiveness. The resistance and flexibility of NBR depend on the acrylonitrile (ACN) content and the curing system used.

  2. Viton®/FKM Metric O-Rings (Fluorocarbon) 75/80 Duro: FKM O-Rings offer excellent resistance to high temperatures and a wide range of chemicals. They are known for their low gas permeability, resistance to aging and ozone, and self-extinguishing properties. FKM materials have varying compositions and fluorine content, providing improved chemical or temperature resistance in specific applications.

  3. EPDM Metric O-Rings (EPR, EPM) Ethylene Propylene Diene Monomer: EPDM O-Rings exhibit good resistance to hot water, steam, polar solvents, silicone oils and greases, and diluted acids. Special formulations of EPDM are suitable for use with glycol-based brake fluids.

  4. Silicone VQM Metric O-Rings: VQM O-Rings have excellent flexibility and can withstand extreme temperatures. They are commonly used in applications requiring resistance to high and low temperatures, as well as in medical and food-grade applications.

These are just a few examples of the materials used for metric O-Rings, and there are other options available depending on specific application requirements.

Metric O-Rings find widespread use in various industries and applications where sealing is necessary. They are employed in both static and dynamic applications, such as fluid or gas sealing in pumps, hydraulic systems, automotive components, machinery, and more. The use of metric dimensions allows for compatibility with international standards, making them suitable for applications worldwide.


 

Information within is believed to be accurate and reliable. However, The O-Ring Store, LLC makes no warranty, expressed or implied, that parts supplied in this material will perform satisfactorily in specific applications. It’s the customer’s responsibility to evaluate the material prior to use.

 

Metric O-Ring Dimensional Tolerances

Metric O-Ring Tolerances
Cross Section (mm) Tolerance (mm)
≤ 2.62 ± 0.08
2.63 – 3.00 ± 0.09
3.01 – 4.50 ± 0.10
4.51 – 5.50 ± 0.13
5.51 – 7.50 ± 0.15
7.51 – 8.50 ± 0.18
8.51 – 10.0 ± 0.20

I.D. (mm) Tolerance (mm)
1.80 – 2.79 ± 0.13
2.80 – 4.86 ± 0.14
4.87 – 6.69 ± 0.15
6.70 – 8.75 ± 0.16
8.76 – 10.59 ± 0.17
10.5 – 11.79 ± 0.18
11.8 – 14.99 ± 0.19
15.0 – 16.99 ± 0.20
17.0 – 18.99 ± 0.21
19.0 – 21.19 ± 0.22
21.2 – 22.39 ± 0.23
22.4 – 24.99 ± 0.24
25.0 – 25.79 ± 0.25
25.8 – 27.99 ± 0.26
28.0 – 29.99 ± 0.28
30.0 – 31.49 ± 0.29
31.5 – 32.49 ± 0.31
32.5 – 34.49 ± 0.32
34.5 – 35.49 ± 0.33
35.5 – 36.49 ± 0.34
36.5 – 37.49 ± 0.35
37.5 – 38.59 ± 0.36
38.7 – 39.99 ± 0.37
40.0 – 41.19 ± 0.38
41.2 – 42.49 ± 0.39
42.5 – 43.69 ± 0.40
43.7 – 44.99 ± 0.41
45.0 – 46.19 ± 0.42
46.2 – 47.49 ± 0.43
47.5 – 48.69 ± 0.44
48.7 – 49.99 ± 0.45
50.0 – 51.49 ± 0.46
51.5 – 52.99 ± 0.47
53.0 – 54.49 ± 0.48
54.5 – 55.99 ± 0.50
56.0 – 57.99 ± 0.51
58.0 – 59.99 ± 0.52
60.0 – 61.49 ± 0.54
61.5 – 52.99 ± 0.55
63.0 – 64.99 ± 0.58
65.0 – 68.99 ± 0.58
I.D. (mm) Tolerance (mm)
67.0 – 68.99 ± 0.59
69.0 – 70.99 ± 0.61
71.0 – 72.99 ± 0.63
73.0 – 74.99 ± 0.64
75.0 – 77.49 ± 0.66
77.5 – 79.99 ± 0.67
80.0 – 82.49 ± 0.69
82.5 – 84.99 ± 0.71
85.0 – 87.49 ± 0.73
87.5 – 89.99 ± 0.75
90.0 – 92.49 ± 0.77
92.5 – 94.99 ± 0.79
95.0 – 97.49 ± 0.81
97.5 – 99.99 ± 0.83
100 – 102.9 ± 0.84
103 – 105.9 ± 0.87
106 – 108.9 ± 0.89
109 – 111.9 ± 0.91
112 – 114.9 ± 0.93
115 – 117.9 ± 0.95
118 – 121.9 ± 0.97
122 – 124.9 ± 1.00
125 – 127.9 ± 1.03
128 – 131.9 ± 1.05
132 – 135.9 ± 1.08
136 – 139.9 ± 1.10
140 – 144.9 ± 1.13
145 – 149.9 ± 1.17
150 – 154.9 ± 1.20
155 – 159.9 ± 1.24
160 – 164.9 ± 1.27
165 – 169.9 ± 1.31
170 – 174.9 ± 1.34
175 – 179.9 ± 1.38
180 – 184.9 ± 1.41
185 – 189.9 ± 1.44
190 – 194.9 ± 1.48
195 – 199.9 ± 1.51
200 – 205.9 ± 1.55
206 – 211.9 ± 1.59
212 – 217.9 ± 1.63
I.D. (mm) Tolerance (mm)
218 – 223.9 ± 1.67
224 – 229.9 ± 1.71
230 – 235.9 ± 1.75
238 – 242.9 ± 1.79
243 – 249.9 ± 1.83
250 – 257.9 ± 1.88
258 – 264.9 ± 1.93
265 – 271.9 ± 1.98
272 – 279.9 ± 2.02
280 – 289.9 ± 2.08
290 – 299.9 ± 2.14
300 – 306.9 ± 2.21
307 – 314.9 ± 2.25
315 – 324.9 ± 2.30
325 – 334.9 ± 2.37
335 – 344.9 ± 2.43
345 – 354.9 ± 2.49
355 – 364.9 ± 2.56
365 – 374.9 ± 2.62
375 – 386.9 ± 2.68
387 – 399.9 ± 2.78
400 – 411.9 ± 2.84
412 – 424.9 ± 2.91
425 – 436.9 ± 2.99
437 – 449.9 ± 3.07
450 – 461.9 ± 3.15
462 – 474.9 ± 3.22
475 – 486.9 ± 3.30
487 – 499.9 ± 3.37
500 – 514.9 ± 3.45
515 – 529.9 ± 3.54
530 – 544.9 ± 3.63
545 – 559.9 ± 3.72
560 – 579.9 ± 3.81
580 – 599.9 ± 3.93
600 – 614.9 ± 4.05
615 – 629.9 ± 4.13
630 – 649.9 ± 4.22
650 – 669.9 ± 4.34
670 – 689.9 ± 4.46
≥ 690 ± 0.65%

 

 
   
Metric o-ring groove designs vary greatly and choosing the right one for your application is important for maximum o-ring performance. This metric o-ring groove design reference guide will help you find the right radius, back-up, pressure and other o-ring dimensions for basic applications.

O-Ring Cross Section

(L) Cylinder Groove Depth

(G) Cylinder Groove Width No Back Up Rings

(G) Cylinder Groove Width One Back Up Ring

(G) Cylinder Groove Width Two Back Up Rings

(L) Flange Groove Depth

(G) Flange Groove Width

(R) Radius without back up ring

(R) Radius with back up ring

1.0

0.8

1.4

0.65

1.4

0.2

0.2

1.2

0.95

1.7

0.8

1.7

0.2

0.2

1.3

1.05

1.8

0.9

1.8

0.2

0.2

1.5

1.2

2.1

1.0

2.1

0.2

0.2

1.6

1.3

2.2

1.1

2.2

0.3

0.2

1.9 & 2.0

1.65

2.5

3.9

5.3

1.4

2.5

0.5

0.2

2.4

2.0

3.2

4.6

6.0

1.7

3.2

0.5

0.3

2.5

2.1

3.4

4.8

6.2

1.8

3.4

0.5

0.3

2.6

2.25

3.6

5.0

6.4

1.9

3.6

0.6

0.3

2.7

2.3

3.7

5.1

6.5

1.95

3.7

0.6

0.3

3.0

2.5

3.9

5.3

6.7

2.2

3.9

0.8

0.3

3.15

2.7

4.0

5.4

6.8

2.3

4.0

0.8

0.4

3.5

3.1

4.8

6.2

7.6

2.7

4.8

1.0

0.4

4.0

3.5

5.4

7.1

8.8

3.1

5.4

1.0

0.4

4.5

4.0

6.0

7.7

9.4

3.4

6.0

1.0

0.4

5.0

4.3

6.7

8.4

10.1

3.9

6.7

1.0

0.4

5.5

4.8

7.3

9.0

10.7

4.4

7.3

1.2

0.6

5.7

5.0

7.7

9.4

11.1

4.6

7.7

1.2

0.6

6.0

5.3

8.2

9.9

11.6

4.8

8.2

1.2

0.6

6.35

5.6

8.7

10.4

12.1

5.1

8.7

1.2

0.6

6.5

5.7

8.9

10.6

12.3

5.4

8.9

1.2

0.6

7.0

6.1

9.5

12.0

14.5

5.8

9.5

1.5

0.6

7.5

6.5

14.4

12.9

15.4

6.2

10.4

1.5

0.6

8.0

7.0

11.0

13.5

16.0

6.6

11.0

1.5

0.6

8.4

7.5

11.7

14.2

16.7

6.9

11.7

2.0

0.6

9.0

7.8

12.5

15.0

17.5

7.4

12.5

2.0

0.6

9.5

8.3

13.3

15.8

18.3

7.8

13.3

2.0

0.6

10.0

8.7

13.5

16.0

18.5

8.3

13.5

2.0

0.6

11.0

9.6

15.5

18.0

20.5

9.1

15.5

3.0

0.6

12.0

10.5

16.8

19.3

21.8

10.3

16.8

3.0

0.6

14.0

12.2

19.0

21.5

24.0

11.6

19.0

3.0

0.6

15.0

13.2

20.0

22.5

25.0

12.5

20.0

3.0

0.6

16.0

14.0

21.5

24.0

26.5

13.5

21.5

3.0

0.6

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