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

ISO 7241 B Series Quick Coupling 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.
ISO 7241 B Quick Couplers Dimensional Requirements
  • 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