The two most common hydraulic coupling families are ISO 7241-1 A ("ISO A") and Flat Face (ISO 16028). Choosing correctly affects leakage, contamination, pressure capacity and total cost of ownership.
ISO A overview
ISO A poppet couplings are the classic, economical choice — widely used on agricultural machinery. They connect easily and are available everywhere, but the recessed poppet traps a little oil that spills on disconnect and can admit dirt.
Flat Face overview
Flat Face (ISO 16028) couplings have flush mating surfaces. They minimise oil loss and air inclusion, resist contamination, and tolerate higher pressure — preferred for construction and demanding mobile equipment.
Side-by-side comparison
| Criterion | ISO A | Flat Face (ISO 16028) |
|---|---|---|
| Oil spillage | Noticeable | Minimal |
| Contamination resistance | Moderate | High |
| Max pressure | 250–350 bar | 350–500 bar |
| Cost | Lower | Higher |
| Best for | Agriculture, light industry | Construction, breakers |
Which one to choose
Choose ISO A for budget-sensitive agricultural use where occasional spillage is acceptable. Choose Flat Face for construction, dusty environments, higher pressure and where cleanliness matters. Never mix standards on the same circuit.