ISO 7241 Series B – Dimensions and requirements of quick-action couplings
In hydraulic fluid power systems, power is transmitted and controlled through a liquid under pressure within an enclosed circuit. Quick-action couplings are used to join or separate fluid conductors quickly and without the use of tools or special devices.
This International Standard specifies the interface dimensions and basic performance requirements for two series of hydraulic quick-action couplings. Both series are in widespread use and have similar technological advantages. Series B is used predominantly in North America and in the chemical industry.
ISO 7241 Series B Dimensional requirements
- Dimension D7 is the gauge diameter.
- Dimension L13 is measured to the ball.
- Diameter D11 is the diameter of the gauge ball.
- Valve is flush to minus from the end of coupling when against the stop.
- Surface roughness values in micrometers
- Minimum hardness shall be 86HR 15N at the ball contact point, in accordance with ISO 6508-1.
- The shape of the groove that receives the bearings in the coupled position is left to the manufacturer.
Dimensional requirements for ISO 7241 Series B couplings – Sizes 1/8″ to 1″
| Body Size (mm) |
Body Size (inch) |
D7 | D8 | D9 | D10 min. |
D11 ±0.0025 |
L10 max. |
L11b | L12 min. |
L13 | L14 min. |
L15 max. |
α2 max. |
| 5 | 1/8" | 16.69 | 12.09 12.19 |
10.8 10.9 |
2.16 | 3.175 | 2.79 | 0.64 1.32 |
7.87 | 11.28 11.48 |
18.92 | 0.5 | 16˚ |
| 6.3 | 1/4" | 21,21 | 15.6 15.7 |
14.1 14.2 |
2.54 | 3.967 | 4.06 | 1.07 1.73 |
9.65 | 13.41 13.61 |
22.1 | 0.5 | |
| 10 | 3/8" | 26,87 | 20.04 20.14 |
19 19.1 |
3.05 | 4.763 | 4.83 | 1.07 1.73 |
12.45 | 15.52 15.72 |
24.89 | 0.5 | |
| 12.5 | 1/2" | 33,45 | 25.65 25.76 |
23.44 23.55 |
4.57 | 5.555 | 5.08 | 1.07 1.73 |
12.19 | 17.17 17.37 |
27.94 | 0.5 | |
| 20 | 3/4" | 41,66 | 32.66 32.77 |
31.34 31.45 |
5.08 | 6.35 | 7.37 | 1.45 2.51 |
18.8 | 22.86 23.06 |
35.56 | 0.6 | |
| 25 | 1" | 49,38 | 40.46 40.56 |
37.69 37.8 |
6.1 | 6.35 | 8.64 | 1.45 2.51 |
20.57 | 27.36 27.56 |
40.39 | 0.7 |
- The size designation corresponds to the nominal size of the hose recommended for use with the coupling; see ISO 4397.
- Radius or chamfer length. Radius with chamfer is optional.
- a Dimension D12 is the gauge diameter.
- b Dimension L18 is measured to the ball.
- c Diameter D17 is the diameter of the gauge ball.
- d The shape of the groove that receives the bearings in the coupled position is left to the manufacturer.
- e Valve closed.
- f The valve opens against the stop.
- g Minimum hardness shall be 86HR 15N at the ball contact point, in accordance with ISO 6508-1 _
Dimensional requirements for Series B couplings – Sizes 1-1/2″ and 2″
| Body Size (mm) |
Body Size (inch) |
D12 | D13 | D14 | D15 min. |
D16 | L16b | L17 min. |
L18 | L19 min. |
L20 max. |
L21 | D17 ±0.0025 |
α3 max. |
| 40 | 1-1/2" | 59.13 | 47.96 48.06 |
44.4 44.5 |
8.89 | 38.05 38.15 |
1.4 2.54 |
32.56 | 38.91 39.17 |
53.34 | 10 | 26.36 26.87 |
7.938 | 21˚ |
| 50 | 2" | 85.6 | 66.55 66.68 |
63.14 63.27 |
10.16 | 53 53.16 |
1.4 2.54 |
38.1 | 45.16 45.42 |
65.02 | 15 | 32 32.51 |
12.7 |
Performance requirements
The performance values specified in this International Standard apply to standard couplings made from carbon steel. The use of any combination of other materials and related performance values shall be agreed upon between the customer and manufacturer.
| Characteristic | 5 (1/8") | 6.3 (1/4") | 10 (3/8") | 12.5 (1/2") | 20 (3/4") | 25 (1") | 40 (1-1/2") | 50 (2") |
| Maximum Rated Pressure in Accordance with ISO 2944 | 25 MPa (250 bar) |
25 MPa (250 bar) |
25 MPa (250 bar) |
25 MPa (250 bar) |
16 Mpa (160 bar) |
10 Mpa (100 bar) |
6.3 MPa (63 bar) |
5 MPa (50 bar) |
| Minimum burst pressure | 100 MPa (1000 bar) |
100 MPa (1000 bar) |
100 MPa (1000 bar) |
100 MPa (1000 bar) |
64 MPa (640 bar) |
40 MPa (400 bar) |
25 MPa (250 bar) |
20 MPa (200 bar) |
| Rated flow | 3 L/min | 12 L/min | 23 l/min | 45 1/min | 106 1/min | 189 1/min | 375 1/min | 560 1/min |
| Maximum pressure drop at rated flow | 1 bar | 1 bar | 1,3 bar | 1,3 bar | 1,3 bar | 1,5 bar | 1,8 bar | 2 bar |
| Rated surge flow | 9 1/min | 36 1/min | 69 1/min | 135 1/min | 300 1/min | 567 1/min | 1125 1/min | 1680 1/min |
| Maximum fluid loss per disconnect | 1 ml | 2 ml | 2.5 ml | 5 ml | 10 ml | 25 ml | 100 ml | 200 ml |
| The size designation corresponds to the nominal size of the hose recommended for use with the coupling; see ISO 4397 | ||||||||
