Air Brake Hose: 1.4 MPa Working, 10 MPa Burst

1.4 MPa maximum working pressure. 10 MPa minimum burst pressure. Those are the first two numbers on our air brake hose datasheet, and they answer exactly one question. Probably not the one you asked first.

Air systems move air, not brake fluid. The pressures are low; the volume is not. That is the whole logic behind the 1.4 MPa working rating on this hose. Put it next to hydraulic brake hose and the gap looks enormous, but the two systems are not in the same business.

What the 1.4 MPa and 10 MPa figures do not tell you: whether a stone chip will cut through the cover on a gravel-yard run. Whether the tube stiffens at a winter loading dock in the north. Whether the fitting was crimped properly in the first place. Pressure ratings stay silent on all three.

Here is the detail that matters for sizing. The working pressure rating is the same across every bore in the range. So if the rating cannot separate the options, something else has to.

The range covers three bores: 4.8 mm, 9.5 mm and 12.7 mm. All rated to 1.4 MPa working. All built the same way: EPDM tube, PVC yarn braid, ozone-resistant EPDM cover. All serviceable from -40 °C to +120 °C. The pressure column of the datasheet is identical from top to bottom.

The 4.8 mm line handles short runs: valve connectors, brake chamber hose, auxiliary circuits. The 9.5 mm is the service-brake circuit hose, from the foot valve through the relay valve out to the chambers. The 12.7 mm is the main supply line, where the distance is long and what counts is moving volume without dropping pressure.

Read that list again and the pattern is clear. Bore follows flow and pressure drop. Never the pressure rating.

If the rating is constant and the construction is constant, what actually changes between the five variants on the datasheet? Wall thickness. The standard-wall 4.8 mm bore carries 4.5 mm of wall. The 9.5 mm standard drops to 3.5 mm. The 12.7 mm comes in at 5 mm.

Then come the thick-wall options. The 9.5 mm bore can be ordered with 4.8 mm of wall. The 12.7 mm thick-wall version carries 4.75 mm. Same working pressure. Same burst pressure. The thick-wall 9.5 mm carries roughly a third more wall than its standard twin. That extra wall is the margin against cuts and chafe. The price is outside diameter.

The standard 9.5 mm hose measures 17 ± 0.4 mm across the outside. The thick-wall version measures 19.1 ± 0.5 mm. Two millimetres sounds like nothing, until the hose has to pass an existing bracket or a grommet sized for the old coil. On paper, the wall wins the argument. In the bay, the outside diameter wins it first.

Start from the routing, not the catalogue. A run tucked along the frame rail can stay standard wall. A run exposed under the chassis, where it takes strikes, drags and rubs on every rough yard, should be specified thick-wall from the start. You have already seen what a chafe spot does to a standard-wall line. That is usually how this decision gets made the second time.

Length is the other half of the spec. Coils get cut and crimped in the workshop to what each vehicle actually needs. Pre-cut lengths arrive with sealed ends, so no dust travels with them.

The fastest way to a match is the vehicle type and the run you are replacing: a valve connector, a chamber hose, a service line or the main supply line. We will come back with the bore, the wall grade, and the coil or cut-length form that fits it.

Cut each run to the length the routing needs, not to what is left on the drum. A hose that fits its route does not need a story. It bolts on, holds pressure, and stays out of the way until the next service.