How to Read a Hydraulic Hose Specification

A hydraulic hose specification table packs a surprising amount of information into a small grid: nominal bore, outside diameter, working pressure, burst pressure, bend radius, often temperature range and fitting standards. To a trained eye it answers every question needed to specify a hose correctly. To everyone else it looks like a wall of numbers.

This guide walks through each column of a typical braided or spiral hose specification table, explains what the numbers mean, and points out the traps that cause mis-specification — the quiet kind that does not fail at the quote stage, but fails six months later on a machine.

1. Why the specification table matters more than the marketing page

Two hoses can carry the same part number family, the same colour cover, and similar marketing copy — and still behave differently in service. The specification table is where the differences live. Companies that publish detailed, consistent tables are telling you something about how they test.

When you compare products, compare tables, not adjectives. Here is what each row is telling you.

2. Column by column

PRODUCT NAME / CODE

The model designation, such as 1SN, 2SN, 1SC, R12, R13, or a manufacturer’s series code. This is the shorthand the industry uses to identify the construction family — for example, 1SN and 2SN correspond to single- and double-braid constructions within the SAE 100R1/100R2 families. The code is the entry point, but never the full specification: always check that the code on the table matches the code on the quote.

STANDARD

The construction standard the hose is built to, for example SAE J517, EN 853, EN 857. If a hose claims conformance to a standard, its key dimensions and pressure ratings should match that standard’s requirements. A table without a stated standard is telling you the dimensions are “typical” — good enough for some applications, risky for others.

LAYERS

The reinforcement description: number of braid or spiral layers of steel wire (or textile, for some constructions). This is the single most important structural row on the table, because pressure capability scales with reinforcement.

Watch for unit sloppiness here. Machine-translated datasheets sometimes render “2 layers” as “2nd Floor” or “2 floors” — an obvious artefact, but one that appears on enough catalogue pages to be worth a second look when a table looks unusual.

NOMINAL BORE / I.D.

The inside diameter — the fluid passage. It is quoted either in inches (1/4″, 3/8″, 1/2″, 3/4″, 1″, 1-1/4″, 2″…) or in millimetres (6, 8, 10, 12.5, 16, 19, 25, 31.5, 38, 51 mm…).

The trap: inch and metric sizes are not freely interchangeable. A 1/2″ hose has an I.D. of about 12.7 mm, and a 12 mm hose is a different part with different fittings. When ordering across suppliers, confirm which unit is being quoted, and confirm the fitting standard matches.

The second trap: I.D. determines flow. An undersized bore raises fluid velocity, which raises pressure drop and heat — a classic cause of systems that “run hot and slow” even though every component is correctly sized.

O.D.

The outside diameter — the total outer envelope of the hose. This is the dimension that decides whether the hose fits through a bulkhead, under a cover, or beside another line. It also matters for clamp sizing.

O.D. varies between manufacturers for the same nominal bore: a heavier cover, a different braid angle, or an extra abrasion wrap all add millimetres. If your assembly is tightly packaged, O.D. is a selection criterion, not an afterthought.

WORKING PRESSURE (W.P.)

The maximum continuous pressure the hose is rated to carry, in bar, MPa, or psi (1 MPa = 10 bar = 145 psi).

Three rules for using this row correctly:

1. Pressure depends on size. Working pressure falls as bore size increases. Never carry one figure across an entire table.

2. Working pressure is not peak pressure. If your circuit generates transient spikes — from relief valves, pump start-up, or fast valve switching — design against the peak, not the nominal. A standard margin is to work at 70–80% of the rated W.P.

3. Pressure derating compounds. Temperature, age, and crimp quality all reduce effective pressure capability. A hose at its listed W.P. is a hose with no margin left for anything else.

BURST PRESSURE (B.P. / MINIMUM BURST PRESSURE)

The pressure at which the hose fails catastrophically — typically around 4× working pressure for braided constructions. This is a safety margin figure, not an operating target.

Why it still matters: the ratio between burst and working pressure tells you how much abuse the construction can absorb before failure. A large gap is a sign of conservative design; a small gap means the hose lives close to its limits. Use it as a quality signal when comparing tables from different suppliers.

MINIMUM BEND RADIUS (Min. B.R.)

The tightest bend the hose can tolerate without kinking or suffering accelerated fatigue. Usually quoted in millimetres, measured to the inside of the bend.

This is the most under-respected row on the table, and the most common root cause of field failures:

A bend tighter than Min. B.R. kinks the reinforcement and creates a permanent weak point.
Repeated flexing near the limit multiplies fatigue damage even if no single bend is below the limit.
At low temperature, the effective minimum bend radius increases — see our guide on low-temperature embrittlement.

Practical rule: measure your actual routing, add 20–30% margin, and only then look up the allowable bend radius.

TEMPERATURE RANGE

The temperature band the hose is rated for, for example -40 °C to +100 °C, or -30 °C to +120 °C for steam service. Standard compounds cover general service; special fluids (phosphate ester, water-based, some solvents) and extreme temperatures require different tube compounds. If your application is outside the printed range, ask — do not assume.

FITTINGS / COUPLING STANDARD

The coupling interface the hose is designed to be crimped with, and sometimes the crimp specification. A hose is only as strong as its fitting connection: a mismatched crimp reduces burst pressure and creates the classic “pull-out” failure at the coupling.

3. A specification checklist you can hand to any supplier

To get an accurate quote and a correct hose, provide these seven items — any supplier worth their salt will ask for them anyway:

1. Bore size (I.D.) and unit used

2. Required length and end fitting types

3. Maximum working pressure, including transient peaks

4. Fluid type and concentration

5. Temperature range, including cold-start conditions

6. Tightest bend radius in the routing

7. Environment: abrasion, UV, weather, chemical splash

With those seven answers, the specification table does the rest of the work.

4. Common mis-specifications and their symptoms

Mistake	Symptom months later
Undersized I.D.	Slow cycle times, overheated fluid, high pressure drop
Working pressure ignored for transients	Bulging, fitting pull-out, burst at bends
Bend radius not checked	Kinked reinforcement, pinhole leaks near bends
Wrong tube compound for fluid	Swollen tube, cover cracking, contamination
Fitting/crimp mismatch	Leakage at coupling, reduced burst strength
Temperature range exceeded	Hardened tube, cracking at cold start

5. Summary

A specification table is a complete engineering document once you know how to read it. The columns that matter most in practice are I.D. (flow), W.P. (pressure margin), and Min. B.R. (routing), with burst pressure as a quality cross-check and temperature range as the guardrail for environment.

Read the table, measure the machine, and specify from data. That process takes ten minutes and eliminates the majority of hydraulic hose failures.

How to Read a Hydraulic Hose Specification Table (ID, OD, W.P., B.P., MBR)