Japanese O-rings

Japanese O-rings - JIS B2401

The use of substitute O-rings in underwater equipment should, in general, be avoided. If substitution is necessary, the following issues should be considered:
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Material type is selected for resistance to damage, chemical attack and UV light. Types used in underwater engineering applications are usually Nitrile-butadiene (NBR), Silicone, or Buna.
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Material hardness is important. Too soft and the O-ring will extrude under pressure, causing catastrophic failure. Too hard and the seal will be stiff and prone to abrasion damage. Underwater housing door, port and control O-rings usually have Shore hardness in the 60 to 75 range.
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Japanese O-rings do not have exact substitutes from the standard European and American inch and metric size ranges.

Given below are the specifications for Japanese Industry Standard (JIS) B2401 series O-rings.
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Once a size has been found, note that a complete spec. also includes material type and hardness. For example, the O-ring for a Nikonos plug is P9, the material is NBR or Silicone, and the Shore hardness (Sh) is 60-70.
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It is not unusual for manufacturers to use non-standard (specially manufactured) sizes.

All dimensions in mm

d = 1.5 ±0.1	D (±0.15)
S 2	1.5
S 3	2.5
S 4	3.5
S 5	4.5
S 6	5.5
S 7	6.5
S 8	7.5
S 9	8.5
S 10	9.5
S 11.2	10.7
S 12	11.5
S 12.5	12.0
S 14	13.5
S 15	14.5
S 16	15.5
S 18	17.5
S 20	19.5
S 22	21.5

d = 1.9 ±0.07	D (±0.12)
P 2	1.8
P 3	2.8
P 4	3.8
P 5	4.8
P 6	5.8
P 7	6.8
P 8	7.8
P 9	8.8
P 10	9.8

d = 2.0 ±0.1	D (±0.15)
S 22.4	21.9
S 24	23.5
S 25	24.5
S 26	25.5
S 28	27.5
S 29	28.5
S 30	29.5
S 31.5	31.0
S 32	31.5
S 34	33.5
S 35	34.5
S 35.5	35.0
S 36	35.5
S 38	37.5
S 39	38.5
S 40	39.5

d = 2.0 ±0.1	D (±0.25)
S 42	41.5
S 44	43.5
S 45	44.5
S 46	45.5
S 48	47.5
S 50	49.5
S 53	52.5
S 55	54.5
S 56	55.5
S 60	59.5
S 63	62.5
S 65	64.5
S 67	66.5
S 70	69.5

d = 2.0 ±0.1	D (±0.4)
S 71	70.5
S 75	74.5
S 80	79.5
S 85	84.5
S 90	89.5
S 95	94.5
S 100	99.5
S 105	104.5
S 110	109.5
S 112	111.5
S 115	114.5
S 120	119.5
S 125	124.5

d = 2.0 ±0.1	D (±0.6)
S 130	129.5
S 132	131.5
S 135	134.5
S 140	139.5
S 145	144.5
S 150	149.5
S 155	154.5
S 160	159.5
S 165	164.5
S 170	169.5
S 175	174.5
S 180	179.5

d = 2.0 ±0.1	D (±0.8)
S 185	184.5
S 190	189.5
S 195	194.5
S 200	199.5
S 205	204.5
S 210	209.5
S 215	214.5
S 220	219.5
S 225	224.5
S 230	229.5
S 235	234.5
S 240	239.5
S 245	244.5
S 250	249.5
S 255	254.5
S 260	259.5
S 265	264.5
S 270	269.5
S 275	274.5
S 280	279.5
S 285	284.5
S 290	289.5
S 295	294.5
S 300	299.5

d = 2.4 ±0.07	D (±0.12)
P 10A	9.8
P 11	10.8
P 11.2	11.0
P 12	11.8
P 12.5	12.3
P 14	13.8
P 15	14.8
P 16	15.8
P 18	17.8

d = 2.4 ±0.07	D (±0.15)
P 20	19.8
P 21	20.8
P 22	21.8

d = 3.1 ±0.1	D (±0.15)
G 25	24.4
G 30	29.4
G 35	34.4
G 40	39.4

d = 3.1 ±0.1	D (±0.25)
G 45	44.4
G 50	49.4
G 52	51.4
G 55	54.4
G 58	57.4
G 60	59.4
G 62	61.4
G 63	62.4
G 64	63.4
G 65	64.4
G 67	66.4
G 70	69.4

d = 3.1 ±0.1	D (±0.40)
G 72	71.4
G 75	74.4
G 80	79.4
G 85	84.4
G 90	89.4
G 95	94.4
G 100	99.4
G 105	104.4
G 110	109.4
G 115	114.4
G 120	119.4
G 125	124.4

d = 3.1 ±0.1	D (±0.60)
G 130	129.4
G 135	134.4
G 140	139.4
G 145	144.4
Gs 150	149.3
Gs 155	154.3
Gs 160	159.3
Gs 165	164.3
Gs 170	169.3
Gs 175	174.3
Gs 180	179.3

d = 3.1 ±0.1	D (±0.80)
Gs 185	184.3
Gs 190	189.3
Gs 195	194.3
Gs 200	199.3
Gs 205	204.3
Gs 210	209.3
Gs 215	214.3
Gs 220	219.3
Gs 225	224.3
Gs 230	229.3
Gs 235	234.3
Gs 240	239.3
Gs 245	244.3
Gs 250	249.3
Gs 255	254.3
Gs 260	259.3
Gs 265	264.3
Gs 270	269.3
Gs 275	274.3
Gs 280	279.3
Gs 285	284.3
Gs 290	289.3
Gs 295	294.3
Gs 300	299.3

d = 3.1 ±0.12	D (±1.20)
Gs 305	304.3
Gs 310	309.3
Gs 315	314.3
Gs 320	319.3
Gs 325	324.3
Gs 330	329.3
Gs 335	334.3
Gs 340	339.3
Gs 345	344.3
Gs 350	349.3
Gs 355	354.3
Gs 360	359.3
Gs 365	364.3
Gs 370	369.3
Gs 375	374.3
Gs 380	379.3
Gs 385	384.3
Gs 390	389.3
Gs 395	394.3
Gs 400	399.3

d = 3.1 ±0.12	D (±1.50)
Gs 405	404.3
Gs 410	409.3
Gs 415	414.3
Gs 420	419.3
Gs 425	424.3
Gs 430	429.3
Gs 435	434.3
Gs 440	439.3
Gs 445	444.3
Gs 450	449.3
Gs 455	454.3
Gs 460	459.3
Gs 465	464.3
Gs 470	469.3
Gs 475	474.3
Gs 480	479.3
Gs 485	484.3
Gs 490	489.3
Gs 495	494.3
Gs 500	499.3

d = 3.5 ±0.1	D (±0.15)
P 22A	21.7
P 22.4	22.1
P 24	23.7
P 25	24.7
P 25.5	25.2
P 26	25.7
P 28	27.7
P 29	28.7
P 29.5	29.2
P 30	29.7
P 31	30.7
P 31.5	31.2
P 32	31.7
P 34	33.7
P 35	34.7
P 35.5	35.2
P 36	35.7
P 38	37.7
P 39	38.7
P 40	39.7

d = 3.5 ±0.1	D (±0.25)
P 41	40.7
P 42	41.7
P 44	43.7
P 45	44.7
P 46	45.7
P 48	47.7
P 49	48.7
P 50	49.7

d = 5.7 ±0.15	D (±0.25)
P 48A	47.6
P 50A	49.6
P 52	51.6
P 53	52.6
P 55	54.6
P 56	55.6
P 58	57.6
P 60	59.6
P 62	61.6
P 63	62.6
P 65	64.6
P 67	66.6
P 70	69.6

d = 5.7 ±0.15	D (±0.4)
P 71	70.6
P 75	74.6
P 80	79.6
P 85	84.6
P 90	89.6
P 95	94.6
P 100	99.6
P 102	101.6
P 105	104.6
P 110	109.6
P 112	111.6
P 115	114.6
P 120	119.6
P 125	124.6

d = 5.7 ±0.15	D (±0.6)
P 130	129.6
P 132	131.6
P 135	134.6
P 140	139.6
P 145	144.6
P 150	149.6

d = 5.7 ±0.15	D (±0.60)
G 150	149.3
G 155	154.3
G 160	159.3
G 165	164.3
G 170	169.3
G 175	174.3
G 180	179.3

d = 5.7 ±0.15	D (±0.80)
G 185	184.3
G 190	189.3
G 195	194.3
G 200	199.3
G 210	204.3
G 215	214.3
G 220	219.3
G 225	224.3
G 230	229.3
G 235	234.3
G 240	239.3
G 245	244.3
G 250	249.3
G 255	254.3
G 260	259.3
G 265	264.3
G 270	269.3
G 275	274.3
G 280	279.3
G 285	284.3
G 290	289.3
G 295	294.3
G 300	299.3

d = 5.7 ±0.15	D (±1.00)
G 305	304.3
G 310	309.3
G 315	314.3
G 320	319.3
G 325	324.3
G 330	329.3
G 335	334.3
G 340	339.3
G 345	344.3
G 350	349.3
G 355	354.3
G 360	359.3
G 365	364.3
G 370	369.3
G 375	374.3
G 380	379.3
G 385	384.3
G 390	389.3
G 395	394.3
G 400	399.3

d = 5.7 ±0.15	D (±1.20)
G 405	404.3
G 410	409.3
G 415	414.3
G 420	419.3
G 425	424.3
G 430	429.3
G 435	434.3
G 440	439.3
G 445	444.3
G 450	449.3
G 455	454.3
G 460	459.3
G 465	464.3
G 470	469.3
G 475	474.3
G 480	479.3
G 485	484.3
G 490	489.3
G 495	494.3
G 500	499.3
G 505	504.3

d = 5.7 ±0.15	D (±1.60)
G 510	509.3
G 515	514.3
G 520	519.3
G 525	524.3
G 530	529.3
G 535	534.3
G 540	539.3
G 545	544.3
G 550	549.3
G 555	554.3
G 560	559.3
G 565	564.3
G 570	569.3
G 575	574.3
G 580	579.3
G 585	584.3
G 590	589.3
G 595	594.3
G 600	599.3

d = 8.4 ±0.15	D (±0.6)
P 150A	149.5
P 155	154.5
P 160	159.5
P 165	164.5
P 170	169.5
P 175	174.5
P 180	179.5

d = 8.4 ±0.15	D (±0.8)
P 185	184.5
P 190	189.5
P 195	194.5
P 200	199.5
P 205	204.5
P 209	208.5
P 210	209.5
P 215	214.5
P 220	219.5
P 225	224.5
P 230	229.5
P 235	234.5
P 240	239.5
P 245	244.5
P 250	249.5
P 255	254.5
P 260	259.5
P 265	264.5
P 270	269.5
P 275	274.5
P 280	279.5
P 285	284.5
P 290	289.5
P 295	294.5
P 300	299.5

d = 8.4 ±0.15	D (±1.0)
P 305	304.5
P 310	309.5
P 315	314.5
P 320	319.5
P 325	324.5
P 330	329.5
P 335	334.5
P 340	339.5
P 345	344.5
P 350	349.5
P 355	354.5
P 360	359.5
P 365	364.5
P 370	369.5
P 375	374.5
P 380	379.5
P 385	384.5
P 390	389.5
P 395	394.5
P 400	399.5

d = 8.4 ±0.15	D (±1.2)
P 405	404.5
P 410	409.5
P 415	414.5
P 420	419.5
P 425	424.5
P 430	429.5
P 435	434.5
P 440	439.5
P 445	444.5
P 450	449.5
P 455	454.5
P 460	459.5
P 465	464.5
P 470	469.5
P 475	474.5
P 480	479.5
P 485	484.5
P 490	489.5
P 495	494.5
P 500	499.5

d = 8.4 ±0.15	D (±1.6)
P 505	504.5
P 510	509.5
P 515	514.5
P 520	519.5
P 525	524.5
P 530	529.5
P 535	534.5
P 540	539.5
P 545	544.5
P 550	549.5
P 555	554.5
P 560	559.5
P 565	564.5
P 570	569.5
P 575	574.5
P 580	579.5
P 585	584.5
P 590	589.5
P 595	594.5
P 600	599.5

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