NEWS CENTER

Read a test report the way the bench reads it. Every test answers one question, and no test answers two. A report with five lines carries five answers; a report with three carries three, and the two that were left out will not come up again until something fails in the field.

Expansion testing: two pressure points, not one

Expansion tells you how far the wall moves when pressure rises. It is quoted in millilitres per metre at 6.9 MPa and 10.3 MPa, and both points belong in a report, because a figure at one pressure has measured half the behaviour.

The numbers also do not travel across bores. Our 3.2 mm low-expansion assembly measures 0.25 ml/m at 6.9 MPa and 0.36 at 10.3 MPa. The 4.8 mm line measures 1.81 and 2.36. The 6.3 mm line measures 2.69 and 3.84. Same construction throughout, and the spread runs past an order of magnitude, which means a single acceptance threshold applied to every size rejects sound 6.3 mm stock and waves through a poor 3.2 mm batch.

Burst testing proves the reinforcement, and stops there

Burst is the number most purchase orders quote, and the one easiest to over-read. It measures what the reinforcement can hold: 80 MPa across most of the 3.2 mm range, 70 on one 3.2 mm build, 60 on the 4.8 mm, 50 on the 6.3 mm.

On the air brake line the same test loses its discriminating power. Every bore carries 1.4 MPa working and 10 MPa burst, so the figure cannot separate one bore from another. What separates them there is the run location and the bore, and the pressure test confirms only that reinforcement is present at all.

The temperature window is a claim with two ends

A working range is two claims, and a report showing only the hot end has tested half of it. The hydraulic range is rated from -48°C to +120°C. The air brake range runs -40°C to +120°C. Cold matters because a cover that cracks at the lower end has failed before the hose ever sees pressure, and heat matters because the compound decides how long the wall keeps its shape.

Neither end answers the question a buyer actually asks, which is how the hose behaves after two years in service. That is a different test on a different timescale, and it does not appear on a shipping report.

What the bench cannot see

Three failures stay invisible to a pressure gauge. A bonding layer that lets the reinforcement separate shows up as a blister or a bulge, never as a pressure drop. A cover that has lost its ozone resistance shows up as hairline cracks before anything leaks. A fitting coating that cannot take salt shows up as corrosion under the crimp, long before the joint weeps.

That is why every shipment leaves with a test report, and why the fitting finish is checked on a 96-hour salt spray rather than assumed. Neither check replaces the other. A batch can pass pressure and salt spray and still separate at the bonding layer under flex, so the report is read as a coverage map, not a verdict.

Questions that make a report auditable

Ask these five before the report is filed:

1. Which of the five tests ran on this batch, and which did not?
2. At what pressure points was expansion measured, and on which bore?
3. Does the burst figure apply to the bore on my order line, or to the whole range?
4. Does the report name the size and the batch, or only the product family?
5. When a test is missing, who signs off on shipping that batch anyway?

A report that answers all five is auditable. A report that answers the first two is a shipping document.

Bring us the report you are working from and the bore on your order line, and we will tell you which line covers what you are buying. The standard brake hose range lists expansion and burst per bore, the low expansion brake hose assemblies carry the 3.2 mm figures quoted above, and the heavy duty range is at jzhose.com.

FAQ

Does a passing test report mean the batch is good? No. It means the batch passed the tests that were run on it. A report carrying expansion and burst says nothing about the bonding layer, the cover's ozone resistance, or how the hose behaves after a thousand pressure cycles. Read the report as a list of what was checked, and treat the missing lines as unknowns rather than as passes.

Which tests should I require in the report? Start with expansion at both pressure points, minimum burst for the bore you are buying, and the working window at both ends. Add the fitting finish if the hose will see salt. Then require that the report names the bore and the batch, because a report written against the product family cannot be matched to the cartons on your dock.

The report listed several tests and the batch still failed in service. How? Because the failure came in a mode none of those tests covers. Delamination at the bonding layer, ozone cracking in the cover, and corrosion at the crimp all pass a static pressure test. If the field failure looks like a bulge, a crack, or a wet crimp rather than a burst, the test set was the problem, not the result.