ISO 15171-1 Connection for fluid power and general use – Hydraulic couplings for diagnostic purposes- Coupling not for connection under pressure

In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an enclosed circuit. In general applications, a fluid may be conveyed under pressure. Components are equipped with ports providing diagnostic points in a hydraulic system. Diagnostic couplings may be installed to aid in the diagnosis of hydraulic systems.

This part of ISO 15171 specifies dimensions, performance requirements, and test procedures for the male quick-action half of a metric coupling with an M14 x 1,5 straight stud end to mate with an ISO 6149-1 port, to be used for diagnostic purposes. Couplings in accordance with this part of ISO 15171 are not designed to connect under pressure. The coupling is designed for use in hydraulic systems that use mineral oil.

This part of ISO 15171 does not apply to the female half of the mating hydraulic quick-action coupling, which is not on the machine.

Couplings in accordance with this part of ISO 15171 may be used at a maximum working pressure of 40 MPa (400 bar). The permissible working pressure depends upon the materials, design, working conditions, application, etc.

Conformance to the dimensional information in this part of ISO 15171 does not guarantee rated performance. Each manufacturer should perform testing in accordance with the specification contained in this part of ISO 15171 to assure that components comply with the performance rating.

Performance requirements

Working pressure and temperature

Couplings shall be designed for use at a maximum working pressure of 40 MPa (400 bar) within a temperature range between -20 °c and + 120 °c. The temperature range of couplings with elastomeric seals depends on the limits of the temperature range of the seals.

Rated flow

The coupling shall be rated to handle a flow of 3 l/min at a maximum pressure drop of 500 kPa (5 bar), with a maximum rated flow without malfunction of 15 l/min.

Burst and cyclic endurance (impulse) pressures

The male half of the coupling shall meet at least a burst pressure of 160 MPa (1 600 bar) and a cyclic endurance (impulse) pressure of 53,2 MPa (532 bar) when tested.

Test methods

Testing shall be conducted in accordance with ISO 8434-5 for burst, cyclic endurance (impulse), and vacuum. The test samples shall be tightened to the torque requirement given in ISO 6149-2 for the M14 x 1,5 size stud end. After the cyclic endurance test, it shall be possible to connect and disconnect the coupling with the female half without leakage, binding, or malfunction. Test results shall be reported using the form given in ISO 8434-5.


Design and dimensions shall conform to dimension requirements. Stud end and O-ring shall be in accordance with ISO 6149-2.

Unless otherwise agreed upon between the supplier and purchaser, seals for stud ends shall be included in the delivery.

  • Width across flats
  • Maximum engagement
  • Hardness 42 HRC to 55 HRC in contact area
  • Ra ≤2,5 μm for 4,57 mm length
  • Valve open
  • This groove is for product marking and attachment of protective cap. Alternate marking location is on hex flats.
  • O-ring
  • Stud end in accordance with ISO 6149-2
  • Identification groove in accordance with ISO 6149-2