3xx87 dash sizesID 0.412–25.940 inAS568

AS568 300 Series O-Rings — 0.210 in Cord

The 300 series runs a 0.210 in cord — 5.33 mm — and it is the first of the heavy families. Large flanges, heavy hydraulic connections and the bigger static joints use it, and it is the largest cord family whose sizes are still commonly held in stock.

AS568-352 — 300 seriesAS568 dimensions · inches · plan view normalised, cord section enlarged · not to a common scale

300 Serieswhat is in this family and where it ends

This family reaches the largest inside diameter this library covers. Its cord tolerance is wider than the three lighter families', which is the standard allowing for how much harder a thick cord is to mould to size.

The 900-series boss gaskets overlap the low end of this family's bore range with much thinner cords. Those are not smaller versions of these — they are seals for a different joint, and the two should not be substituted on the strength of a bore dimension alone.

This is 87 dash numbers, from the -309 at 0.412 in (10.46 mm) inside diameter to the -395 at 25.940 in (658.88 mm). Every size in it carries a 0.210 in (5.33 mm) cord.

The numbering in this family is continuous across -309 to -395: there are no missing dash numbers inside the range.

All 87 sizesdash number, inside diameter, cord and tolerances

Dash	ID (in)	ID (mm)	Cord (in)	Cord (mm)	ID tol.	Cord tol.
-309	0.412	10.46	0.210	5.33	±0.005	±0.005
-310	0.475	12.07	0.210	5.33	±0.005	±0.005
-311	0.537	13.64	0.210	5.33	±0.007	±0.005
-312	0.600	15.24	0.210	5.33	±0.009	±0.005
-313	0.662	16.81	0.210	5.33	±0.009	±0.005
-314	0.725	18.42	0.210	5.33	±0.010	±0.005
-315	0.787	19.99	0.210	5.33	±0.010	±0.005
-316	0.850	21.59	0.210	5.33	±0.010	±0.005
-317	0.912	23.16	0.210	5.33	±0.010	±0.005
-318	0.975	24.77	0.210	5.33	±0.010	±0.005
-319	1.037	26.34	0.210	5.33	±0.010	±0.005
-320	1.100	27.94	0.210	5.33	±0.012	±0.005
-321	1.162	29.51	0.210	5.33	±0.012	±0.005
-322	1.225	31.12	0.210	5.33	±0.012	±0.005
-323	1.287	32.69	0.210	5.33	±0.012	±0.005
-324	1.350	34.29	0.210	5.33	±0.012	±0.005
-325	1.475	37.47	0.210	5.33	±0.015	±0.005
-326	1.600	40.64	0.210	5.33	±0.015	±0.005
-327	1.725	43.82	0.210	5.33	±0.015	±0.005
-328	1.850	46.99	0.210	5.33	±0.015	±0.005
-329	1.975	50.17	0.210	5.33	±0.018	±0.005
-330	2.100	53.34	0.210	5.33	±0.018	±0.005
-331	2.225	56.52	0.210	5.33	±0.018	±0.005
-332	2.350	59.69	0.210	5.33	±0.018	±0.005
-333	2.475	62.87	0.210	5.33	±0.020	±0.005
-334	2.600	66.04	0.210	5.33	±0.020	±0.005
-335	2.725	69.22	0.210	5.33	±0.020	±0.005
-336	2.850	72.39	0.210	5.33	±0.020	±0.005
-337	2.975	75.57	0.210	5.33	±0.024	±0.005
-338	3.100	78.74	0.210	5.33	±0.024	±0.005
-339	3.225	81.92	0.210	5.33	±0.024	±0.005
-340	3.350	85.09	0.210	5.33	±0.024	±0.005
-341	3.475	88.27	0.210	5.33	±0.024	±0.005
-342	3.600	91.44	0.210	5.33	±0.028	±0.005
-343	3.725	94.62	0.210	5.33	±0.028	±0.005
-344	3.850	97.79	0.210	5.33	±0.028	±0.005
-345	3.975	100.97	0.210	5.33	±0.028	±0.005
-346	4.100	104.14	0.210	5.33	±0.028	±0.005
-347	4.225	107.32	0.210	5.33	±0.030	±0.005
-348	4.350	110.49	0.210	5.33	±0.030	±0.005
-349	4.475	113.67	0.210	5.33	±0.030	±0.005
-350	4.600	116.84	0.210	5.33	±0.030	±0.005
-351	4.725	120.02	0.210	5.33	±0.030	±0.005
-352	4.850	123.19	0.210	5.33	±0.030	±0.005
-353	4.975	126.37	0.210	5.33	±0.037	±0.005
-354	5.100	129.54	0.210	5.33	±0.037	±0.005
-355	5.225	132.72	0.210	5.33	±0.037	±0.005
-356	5.350	135.89	0.210	5.33	±0.037	±0.005
-357	5.475	139.07	0.210	5.33	±0.037	±0.005
-358	5.600	142.24	0.210	5.33	±0.037	±0.005
-359	5.725	145.42	0.210	5.33	±0.037	±0.005
-360	5.850	148.59	0.210	5.33	±0.037	±0.005
-361	5.975	151.77	0.210	5.33	±0.037	±0.005
-362	6.225	158.12	0.210	5.33	±0.040	±0.005
-363	6.475	164.47	0.210	5.33	±0.040	±0.005
-364	6.725	170.82	0.210	5.33	±0.040	±0.005
-365	6.975	177.17	0.210	5.33	±0.040	±0.005
-366	7.225	183.52	0.210	5.33	±0.045	±0.005
-367	7.475	189.87	0.210	5.33	±0.045	±0.005
-368	7.725	196.22	0.210	5.33	±0.045	±0.005
-369	7.975	202.57	0.210	5.33	±0.045	±0.005
-370	8.225	208.92	0.210	5.33	±0.050	±0.005
-371	8.475	215.27	0.210	5.33	±0.050	±0.005
-372	8.725	221.62	0.210	5.33	±0.050	±0.005
-373	8.975	227.97	0.210	5.33	±0.050	±0.005
-374	9.225	234.32	0.210	5.33	±0.055	±0.005
-375	9.475	240.67	0.210	5.33	±0.055	±0.005
-376	9.725	247.02	0.210	5.33	±0.055	±0.005
-377	9.975	253.37	0.210	5.33	±0.055	±0.005
-378	10.475	266.07	0.210	5.33	±0.060	±0.005
-379	10.975	278.77	0.210	5.33	±0.060	±0.005
-380	11.475	291.47	0.210	5.33	±0.065	±0.005
-381	11.975	304.17	0.210	5.33	±0.065	±0.005
-382	12.975	329.57	0.210	5.33	±0.065	±0.005
-383	13.975	354.97	0.210	5.33	±0.070	±0.005
-384	14.975	380.37	0.210	5.33	±0.070	±0.005
-385	15.955	405.26	0.210	5.33	±0.075	±0.005
-386	16.955	430.66	0.210	5.33	±0.080	±0.005
-387	17.955	456.06	0.210	5.33	±0.085	±0.005
-388	18.955	481.46	0.210	5.33	±0.090	±0.005
-389	19.955	506.86	0.210	5.33	±0.095	±0.005
-390	20.955	532.26	0.210	5.33	±0.095	±0.005
-391	21.955	557.66	0.210	5.33	±0.100	±0.005
-392	22.940	582.68	0.210	5.33	±0.105	±0.005
-393	23.940	608.08	0.210	5.33	±0.110	±0.005
-394	24.940	633.48	0.210	5.33	±0.115	±0.005
-395	25.940	658.88	0.210	5.33	±0.120	±0.005

Inches are the standard’s own units; millimetre values are conversions — inch × 25.4, rounded to two decimals — and not the ISO 3601-1 metric sizes. Outside diameter is a reference value derived as ID + 2 × cross-section; the two diameters the standard fixes are the inside diameter and the cord.

Tolerances are the per-size figures the standard gives, not a value derived from the diameter — the same inside diameter can carry a different tolerance in a different series, and each page prints its own.

Reading a 3xx dash numberwhat the digits do and do not tell you

Every dash number in this family starts with the digit 3, which is what puts it here. The remaining two digits are its position in the family, counted upwards by inside diameter — they are not a size code, and nothing in them can be multiplied or read off to get a dimension. Two rings whose numbers differ by one can differ by a hundredth of an inch or by a quarter of one.

A cord family is named for the cord its sizes are built on, and the name is a fair description of every size in it only when the family has a single cord throughout. This one does — it carries 0.210 in (5.33 mm).

AS568-214ID 0.984 · cord 0.139 in