Short answer
In 24° metric connections, the tube diameter, connection type and L/S series information are required in addition to the thread size. The light and heavy series names are not sufficient for selecting by appearance or for mixing different series.
Technical explanation
ISO 8434-1 covers the 24° cone connection family. Different connection forms and series sizes may exist within the same family. A cutting ring tube assembly and an O-ring hose fitting end should not be treated as the same operation; the mating geometry is verified. Tube outside diameter, hose inside diameter and nut thread are different areas of definition. A series decision should not be made from the wrench flats of the nut alone without seeing the manufacturer's drawing.
Topic-specific checkpoints
| Item | Description |
|---|---|
| Tube diameter | Dimension separate from the hose inside diameter |
| Thread | Diameter and pitch |
| Series | L/S and the manufacturer's connection designation |
| Seat | 24° geometry and seal/ring design |
How is it assessed in practice?
On the sample form, record the tube outside diameter or hose size, the nut thread, the seat cone and the series marking on it separately. In an L/S comparison, check whether the same nominal number may belong to different measurement systems. Ask for the full product code of the connection element together with the mating part drawing. Do not transfer the torque or pre-assembly method from another series. In the event of a leak, first verify that the parts come from the same system; tightening harder does not eliminate a mismatch.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
Are L and S parts with the same thread size interchangeable?
They should not be considered directly interchangeable. Series, tube diameter and seat geometry must be verified together.
Source coverage
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S019
4 Easy Steps to Identify Hydraulic Threads Parker Hannifin · accessed 2026-10-19 PDF page 1-2: thread identification
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S071
ISO 8434-1:2018 ISO · accessed 2026-10-19 Abstract; 24-degree cone connectors; revision status