Fitting family
Metric DIN 24° cone fittings
Metric thread with a 24° cone inside the male, in a light (L) and a heavy (S) series sized by tube outside diameter.
What it is
The DIN fitting body has a 24° cone machined inside the male end and a counterbore that accepts a tube of a specific outside diameter. Originally it clamps a steel tube with a cutting ring; hose fittings use a swivel female with a matching cone, usually carrying an O-ring.
There are two series. Light (L) is for general pressures. Heavy (S) has a thicker wall and a larger thread for the same tube size, for higher pressures. A fitting is named by tube outside diameter and series, such as 12L or 16S.
- Thread
- Parallel metric fine, pitch in millimetres
- Seal
- 24° cone, with a cutting ring or an O-ring on the female cone
- Standard
- ISO 8434-1 / DIN 2353
- Also called
- DIN 2353, 24° cone, cutting ring, DKOL (light), DKOS (heavy)
What it looks like
How to recognise it
- The thread is metric: the pitch is 1.5 mm or 2.0 mm, and the diameter is a whole number of millimetres.
- Inside the male end there is a shallow 24° cone, then a counterbore.
- Measure the counterbore: its diameter is the tube size that names the fitting.
- The same thread appears in both series for different tube sizes, so the counterbore is needed as well as the thread.
Where it is used
The standard on German and most continental European machines, and widespread on Chinese-built equipment. Found on Volvo, Liebherr and other European brands.
Size chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 6L (tube OD 6 mm) | M12x1.5 | 12.00 mm / 0.472 in | 1.5 mm |
| 8L (tube OD 8 mm) | M14x1.5 | 14.00 mm / 0.551 in | 1.5 mm |
| 10L (tube OD 10 mm) | M16x1.5 | 16.00 mm / 0.630 in | 1.5 mm |
| 12L (tube OD 12 mm) | M18x1.5 | 18.00 mm / 0.709 in | 1.5 mm |
| 15L (tube OD 15 mm) | M22x1.5 | 22.00 mm / 0.866 in | 1.5 mm |
| 18L (tube OD 18 mm) | M26x1.5 | 26.00 mm / 1.024 in | 1.5 mm |
| 22L (tube OD 22 mm) | M30x2 | 30.00 mm / 1.181 in | 2 mm |
| 28L (tube OD 28 mm) | M36x2 | 36.00 mm / 1.417 in | 2 mm |
| 35L (tube OD 35 mm) | M45x2 | 45.00 mm / 1.772 in | 2 mm |
| 42L (tube OD 42 mm) | M52x2 | 52.00 mm / 2.047 in | 2 mm |
Seal: 24° internal cone, with a cutting ring or an O-ring cone (DKOL). The male has a 24° internal cone and a counterbore that fits the tube OD shown.
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| 6S (tube OD 6 mm) | M14x1.5 | 14.00 mm / 0.551 in | 1.5 mm |
| 8S (tube OD 8 mm) | M16x1.5 | 16.00 mm / 0.630 in | 1.5 mm |
| 10S (tube OD 10 mm) | M18x1.5 | 18.00 mm / 0.709 in | 1.5 mm |
| 12S (tube OD 12 mm) | M20x1.5 | 20.00 mm / 0.787 in | 1.5 mm |
| 14S (tube OD 14 mm) | M22x1.5 | 22.00 mm / 0.866 in | 1.5 mm |
| 16S (tube OD 16 mm) | M24x1.5 | 24.00 mm / 0.945 in | 1.5 mm |
| 20S (tube OD 20 mm) | M30x2 | 30.00 mm / 1.181 in | 2 mm |
| 25S (tube OD 25 mm) | M36x2 | 36.00 mm / 1.417 in | 2 mm |
| 30S (tube OD 30 mm) | M42x2 | 42.00 mm / 1.654 in | 2 mm |
| 38S (tube OD 38 mm) | M52x2 | 52.00 mm / 2.047 in | 2 mm |
Seal: 24° internal cone, with a cutting ring or an O-ring cone (DKOS). The male has a 24° internal cone and a counterbore that fits the tube OD shown. Heavy series has a thicker wall than light series.
Commonly confused with
- Light versus heavy series
- M18×1.5 is 12L and also 10S. M22×1.5 is 15L and 14S. Measure the tube counterbore to tell which.
- Komatsu 30° flare
- Uses the same metric fine threads with a 30° seat.
- Metric 60° cone
- Some Asian fittings use metric threads with a 60° cone. Check the cone angle.
Interchangeability
A DIN fitting connects only to the same series and tube size. Light and heavy series do not interchange even when the thread is the same, because the cone and counterbore differ.
Frequently asked questions
What is the difference between DIN light and heavy series?
Heavy series (S) has a thicker body and a larger thread for the same tube size and is rated for higher pressure. For a 12 mm tube, light series uses M18×1.5 and heavy series uses M20×1.5.
What do DKOL and DKOS mean?
They are the common names for metric female swivel hose fittings with a 24° cone and O-ring: DKOL for the light series and DKOS for the heavy series.
How do I identify a metric hydraulic fitting?
Measure the thread outside diameter in millimetres and the pitch with a metric gauge, then measure the tube counterbore inside the male. Thread and counterbore together give the series and size.
Related
- All hydraulic fitting types
- Hydraulic thread identifier
- Unit and dash-size converter
- Fitting code decoder
- Find hose length and fittings by machine model
Dimensions are nominal reference values. Confirm against the standard or the fitting manufacturer before ordering.