ISO 16028 standard Flush-face type, quick-action couplings for use at pressures of 20 MPa (200 bar) to 31,5 MPa (315 bar)
ISO 16028 specifies the interface dimensions for interchangeability and specifies the performance requirements for the hydraulic, flush-face type, quick-action couplings for use at pressures of 20 MPa (200 bar) to 31,5 MPa (315 bar), depending upon the coupling size.
Couplings in accordance with this International Standard are not designed to connect or disconnect under pressure.
Couplings in accordance with this International Standard provide for automatic sealing of the fluid pressure on the upstream side and on the downstream side when the coupling is disconnected.
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 quickly fluid conductor lines, without the use of tools or special devices.
ISO 16028 standard – Dimensional requirements

Body Size mm |
Body Size inch |
A | B | C | D | F | H | J | L | ||||
min. | max. | min. | max. | min. | max. | max. | min. | max. | min. | ±0.0025 | |||
6.3 | 1/4" | 20.50 | 16.10 | 16.20 | 13.85 | 14.05 | 9,70 | 9,75 | 0,6 | 5,70 | 5,80 | 11,56 | 3,175 |
10 | 3/8" | 24.10 | 19.66 | 19.79 | 17.53 | 17.73 | 12,65 | 12,70 | 0,6 | 4,68 | 4,86 | 16,25 | 3,175 |
12.5 | 1/2" | 30.15 | 24.45 | 24.58 | 21,90 | 22. 10 | 15,62 | 15,70 | 0,7 | 9,75 | 9,95 | 17,35 | 3,969 |
16 | 5/8" | 32.65 | 26.95 | 27.08 | 24,40 | 24,60 | 17,62 | 17,70 | 0,7 | 9,75 | 9,95 | 17,35 | 3,969 |
19 | 3/4" | 36.68 | 29.87 | 30.00 | 26,80 | 27,00 | 20,67 | 20,75 | 0,9 | 11,30 | 11,50 | 23,20 | 4,7625 |
25 | 1" | 44.85 | 35.94 | 36.07 | 31,90 | 32,10 | 23,67 | 23,75 | 1, 1 | 10,80 | 11,00 | 23,20 | 6,350 |
Body Size mm |
Body Size inch |
M | N | R | T | U | K | Q | |||||
min. | min. | max. | max. | min. | max. | min. | max. | min. | max. | min. | max. | ||
6.3 | 1/4" | 10.80 | 0,18 | 0,33 | 7,65 | 20,70 | 20,80 | 0,25 | 0,75 | 9,55 | 9,60 | 13,85 | 13,95 |
10 | 3/8" | 15.60 | 0,25 | 0,41 | 9,65 | 23 ,24 | 23,34 | 0,25 | 1,15 | 12,50 | 12,57 | 18, 11 | 18,21 |
12.5 | 1/2" | 16,90 | 0,25 | 0,41 | 10,40 | 30,40 | 30,50 | 0,5 | 1 | 15,51 | 15,58 | 20,30 | 20,40 |
16 | 5/8" | 17,50 | 0,30 | 0,46 | 10,50 | 32,90 | 33,00 | 0,5 | 1 | 17,48 | 17,55 | 20,30 | 20,40 |
19 | 3/4" | 21,50 | 0,30 | 0,46 | 11,25 | 38,00 | 38,10 | 0,5 | 1 | 20,48 | 20,55 | 27,30 | 27,40 |
25 | 1" | 22,60 | 0,43 | 0,58 | 13,05 | 45,25 | 45,35 | 0,75 | 1,25 | 23,48 | 23 ,55 | 29,85 | 29,95 |
ISO 16028 standard – Performance Requirements
Characteristic | 1/4" | 3/8" | 1/2" | 5/8" | 3/4" | 1" |
Rated operating pressure, in accordance with ISO 4399 |
31,5 MPa | 25MPa | 25MPa | 25MPa | 25MPa | 20MPa |
Minimum burst pressure | 126 MPa | 100 MPa | 100 MPa | 100 MPa | 100 MPa | 8OMPa |
Rated flow | 12 1/min | 23 1/min | 45 1/min | 74 1/min | 100 1/min | 189 1/min |
Maximum pressure drop at rated flow |
1 bar | 1 bar | 1 bar | 1 bar | 1 bar | 1 bar |
Rated surge flow | 36 1/min | 69 1/min | 135 1/min | 222 1/min | 300 1/min | 567 1/min |
Maximum fluid loss per disconnect |
0,02 ml | 0,035 ml | 0,07 ml | 0,1 ml | 0,15 ml | 0,25 ml |