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ISO 8434-1 · DIN 2353

Metric 24 degree cone, DIN 2353 / ISO 8434-1, light (L) and heavy (S) series

A straight metric thread with a 24 degree internal cone, sealed by a cutting ring biting into the tube or by a soft seal captured in the cone.

20 sizes60 degree flanksParallel thread24 degree cone (DIN)

Identify a fittingCompare with a lookalike
24 degree cone (DIN), on a parallel thread2424 degree boreParallel threadOpen end on the left
Schematic cross-section of the male half, upper side only, with the centre line dashed and the open end on the left. Cone angles are drawn at their true angle from the axis; nothing else is to scale and no dimension should be measured off it.

How to recognise it

A shallow internal cone at the bottom of a straight metric port, with a cutting ring or a captive soft seal sitting in it.

Where it seals: The 24 degree cone against a cutting ring bitten into the tube, or against a soft seal captured in the cone on the sealing-cone version.

The cutting ring and the tube outside diameter have to match the series. A light-series ring on a heavy-series body, or the wrong tube diameter, will not bite properly and the joint will blow out under pressure.

How it is sized

Sized by tube outside diameter in millimetres AND by series: the same thread can carry two different tube sizes depending on whether it is light or heavy series.

Where you will find it: European hydraulics, mobile and industrial machinery built in Germany, Italy, Scandinavia and increasingly Asia.

Also searched as: DIN 2353, 24 degree cone, metric bite type, DIN fitting, L series, S series.

All sizes

Metric DIN 24 degree size table

Thread, pitch, diameters and working pressure for every Metric DIN 24 degree size in the database.
SizeThreadTPI / pitchBasic major ØMeasured across crestsTube ODWorking pressure
6L (M12 x 1.5)M12 x 1.51.5 mm pitch12 mm / 0.472 inNot published6 mm250 to 315 bar (3,626 to 4,569 psi)
8L (M14 x 1.5)M14 x 1.51.5 mm pitch14 mm / 0.551 inNot published8 mm250 to 315 bar (3,626 to 4,569 psi)
10L (M16 x 1.5)M16 x 1.51.5 mm pitch16 mm / 0.63 inNot published10 mm250 to 315 bar (3,626 to 4,569 psi)
12L (M18 x 1.5)M18 x 1.51.5 mm pitch18 mm / 0.709 inNot published12 mm250 to 315 bar (3,626 to 4,569 psi)
15L (M22 x 1.5)M22 x 1.51.5 mm pitch22 mm / 0.866 inNot published15 mm250 to 315 bar (3,626 to 4,569 psi)
18L (M26 x 1.5)M26 x 1.51.5 mm pitch26 mm / 1.024 inNot published18 mm160 to 315 bar (2,321 to 4,569 psi)
22L (M30 x 2.0)M30 x 2.02 mm pitch30 mm / 1.181 inNot published22 mm160 bar (2,321 psi)
28L (M36 x 2.0)M36 x 2.02 mm pitch36 mm / 1.417 inNot published28 mm100 to 160 bar (1,450 to 2,321 psi)
35L (M45 x 2.0)M45 x 2.02 mm pitch45 mm / 1.772 inNot published35 mm100 to 160 bar (1,450 to 2,321 psi)
42L (M52 x 2.0)M52 x 2.02 mm pitch52 mm / 2.047 inNot published42 mm100 to 160 bar (1,450 to 2,321 psi)
6S (M14 x 1.5)M14 x 1.51.5 mm pitch14 mm / 0.551 inNot published6 mm630 bar (9,137 psi)
8S (M16 x 1.5)M16 x 1.51.5 mm pitch16 mm / 0.63 inNot published8 mm630 bar (9,137 psi)
10S (M18 x 1.5)M18 x 1.51.5 mm pitch18 mm / 0.709 inNot published10 mm630 bar (9,137 psi)
12S (M20 x 1.5)M20 x 1.51.5 mm pitch20 mm / 0.787 inNot published12 mm630 bar (9,137 psi)
14S (M22 x 1.5)M22 x 1.51.5 mm pitch22 mm / 0.866 inNot published14 mm630 bar (9,137 psi)
16S (M24 x 1.5)M24 x 1.51.5 mm pitch24 mm / 0.945 inNot published16 mm400 bar (5,802 psi)
20S (M30 x 2.0)M30 x 2.02 mm pitch30 mm / 1.181 inNot published20 mm400 bar (5,802 psi)
25S (M36 x 2.0)M36 x 2.02 mm pitch36 mm / 1.417 inNot published25 mm400 bar (5,802 psi)
30S (M42 x 2.0)M42 x 2.02 mm pitch42 mm / 1.654 inNot published30 mm250 to 400 bar (3,626 to 5,802 psi)
38S (M52 x 2.0)M52 x 2.02 mm pitch52 mm / 2.047 inNot published38 mm250 to 315 bar (3,626 to 4,569 psi)

20 of the 20 sizes carry a published working pressure. Every one of them prints the exact conditions it applies under on its own page - a figure without its material and safety factor is not a rating.

On paper

Identification sheets covering Metric DIN 24 degree

Metric DIN 2353 / ISO 8434-1, light and heavy series1 sectionsSeat and thread identification: all ten standards1 sectionsPublished working pressures, with the conditions they apply under5 sections

Where these figures come from

Dimensions are as defined by ISO 8434-1, DIN 2353. FittingKey is an independent reference and is not affiliated with, endorsed by or approved by any standards body or fitting manufacturer.

Every value on this page was checked against 5 independent published sources:

Which published source supplied each column, and what it gave.
ColumnSourcesWhat they gave
Dash and trade sizegates-idchart, adaptall-24, mcgill-id, apex-threadidFour publishers give the same thread-to-tube map for both series, including the eight threads that carry a different tube size in each series.
Basic major diametergates-idchart, mcgill-idThe basic major diameter of an ISO metric thread is the number in its designation: M18 x 1.5 measures 18 mm across the crests. Both charts print exactly that.
Working pressuretubes-int, adaptall-24One publisher gives the ISO 8434-1 cutting-ring figure together with the spread across producers and states the conditions in full - carbon or stainless steel, static, safety factor 4. The other gives a single figure per size band. Where they differ the page prints both.

Sources disagree: DIN 2353 heavy series, 30 mm tube, working pressure.

  • 400 bar (adaptall-24)
  • 250 bar as the ISO 8434-1 cutting-ring figure, 250 to 315 bar across producers (tubes-int)

The 400 bar figure sits outside the producer range the other source publishes for the same size band, which is the only place in the metric table where that happens. Both figures are printed on the size page. Assume the lower one unless the fitting's own catalogue says otherwise.