A hydraulic hose datasheet stands on five numbers: working pressure (quoted per DN at +20 °C, it falls as bore rises), burst pressure (minimum 4 × working pressure for wire-reinforced hydraulic hose), temperature range of the tube compound, minimum bend radius, and impulse cycle rating. This article decodes each parameter, with real EN 853/EN 856 tables, so you can read any manufacturer's datasheet critically. If you want the ordering workflow instead, use the companion 12-criteria selection checklist.
What does "working pressure" actually mean?
Working pressure (WP) is the maximum continuous operating pressure of the assembly at +20 °C, and it is size-specific. The single most common datasheet misreading is carrying one pressure figure across a hose family. Reinforcement mechanics forbid it: hoop stress rises with diameter, so the same construction holds far less pressure in a large bore.
| DN | EN 853 1SN | EN 853 2SN | EN 856 4SP | EN 856 4SH |
|---|---|---|---|---|
| DN 6 | 250 bar | 415 bar | — | — |
| DN 10 | 180 bar | 330 bar | 445 bar | — |
| DN 12 | 160 bar | 275 bar | 415 bar | — |
| DN 16 | 130 bar | 250 bar | 350 bar | — |
| DN 19 | 105 bar | 215 bar | 350 bar | 420 bar |
| DN 25 | 88 bar | 165 bar | 280 bar | 380 bar |
| DN 31 | 63 bar | 125 bar | 210 bar | 325 bar |
| DN 38 | 50 bar | 90 bar | 185 bar | 290 bar |
| DN 51 | 40 bar | 80 bar | 165 bar | 250 bar |
The deliberate exceptions are the constant-pressure spiral types of EN 856: R12 = 280 bar, R13 = 345 bar, R15 = 420 bar across their size ranges, designed so fleet engineers can standardise one pressure class in every bore.
Three related figures complete the pressure picture:
- Burst pressure, the destructive qualification value; wire-reinforced hydraulic hose is qualified at a minimum 4:1 burst-to-WP ratio. It is not an operating reserve. (Safety factors are class-specific: PTFE hose is commonly 3:1, unreinforced hose around 5:1, never transplant factors between families.)
- Proof pressure, non-destructive verification at about 1.5 × WP, tested per ISO 1402.
- Pressure spikes, valve-shift transients can exceed nominal pressure by 30–100 % and are the dominant driver of wire fatigue. If spikes exceed ~1.25 × nominal, move from braid to spiral construction.
How does temperature derate the hose?
All catalogue pressures assume +20 °C; as temperature rises, the elastomer softens and the effective rating falls, apply the manufacturer's derating curve, not the headline figure.
| Tube compound | Typical continuous range | Typical media |
|---|---|---|
| NBR (standard hydraulic) | −40 to +100 °C (short peaks ~+120 °C) | Mineral oils, HFA/HFB |
| HNBR / heat-stabilised | −40 to +120/140 °C | Hot mineral oil circuits |
| EPDM | −40 to +140 °C | Water-glycol (HFC), never mineral oil |
| PTFE liner | −70 to +260 °C | Phosphate esters (HFD-R), extreme temps |
Measure the fluid temperature at the pump outlet (the hottest point) and include radiant sources along the routing, a hose passing 50 mm from an exhaust manifold operates far above the fluid temperature. Sustained operation above the tube rating hardens the cover, embrittles the tube and shows up as premature cracking long before the pressure rating is ever challenged.
What does minimum bend radius control?
Minimum bend radius (MBR) is the tightest centreline radius at which the reinforcement still works as designed; below it, wires at the bend take strain beyond their fatigue limit on every pressure cycle. MBR is size- and construction-specific, spiral hose is stiffer than braid:
| DN | EN 853 2SN (typical MBR) | EN 856 4SH (typical MBR) |
|---|---|---|
| DN 12 | ≈ 180 mm | — |
| DN 19 | ≈ 240 mm | ≈ 280 mm |
| DN 25 | ≈ 300 mm | ≈ 340 mm |
| DN 38 | ≈ 500 mm | ≈ 560 mm |
| DN 51 | ≈ 630 mm | ≈ 700 mm |
Violating MBR, even briefly during installation, can halve impulse life, and the eventual mid-body failure rarely gets traced back to the routing error. Design rules that keep assemblies inside their MBR: keep a straight tangent behind each ferrule (the crimp zone is the highest-stress region), use elbow adaptors instead of tight hose bends, add ~20 % radius margin in dynamic flexing zones, and consider compact constructions (EN 857 2SC, ISO 11237) where space is genuinely tight.
What do impulse ratings tell you?
Impulse testing cycles the assembly with pressure pulses at elevated temperature and reports the cycles survived, the datasheet's proxy for fatigue life in dynamic circuits. Braided types are qualified to lower cycle counts than spiral types; performance-based ISO 18752 classifies hoses by grade, with the top grades qualified to one million impulse cycles. A mobile machine's boom circuit can accumulate hundreds of thousands of cycles a year, which is why braided hose that passes every static test still needs annual replacement in such duty while spiral hose runs multiples of that. Ask for the impulse qualification of the specific hose and size, not a family-level claim.
The remaining datasheet lines, decoded
- Fluid compatibility: match the tube to the specific fluid formulation — NBR for mineral oil, EPDM for water-glycol (never oil), PTFE for phosphate esters. See the manufacturer's matrix, not a generic elastomer chart.
- Length change under pressure: typically −4 % to +2 %; install with slack, never taut.
- Vacuum: standard hydraulic hose is not rated for sustained suction, suction lines need internal-helix support; check the collapse rating.
- Electrical properties: antistatic/conductive requirements (ATEX, mining) are verified by resistance testing to ISO 8031, require the certificate.
- Crimp data: hose OD tolerance and ferrule/crimp diameter are part of the qualified system; a fraction of a millimetre off published crimp data compromises the rated pressure.
- Marking: a compliant hose is branded with manufacturer, type/standard, DN, WP and date, verify it on receipt against the order.
Which standard governs which construction?
- EN 853, wire-braid types 1SN/2SN (approximate counterparts of SAE 100R1AT/R2AT, similar, not 1:1 interchangeable).
- EN 857, compact braid 1SC/2SC: smaller OD and tighter MBR at 2SN-class pressures.
- EN 856, spiral types 4SP/4SH plus constant-pressure R12/R13/R15.
- EN 854, textile-braid types for low pressure.
- EN 855 / ISO 3949, thermoplastic types (R7/R8), including non-conductive versions.
- ISO 18752, performance-graded alternative: specifies impulse class and duty, leaving construction to the manufacturer.
- ISO 1402, hydrostatic proof/burst test methods; ISO 4413, hydraulic system safety practice, including hose inspection expectations.
For circuits with incidental food contact, the tube compound additionally needs EC 1935/2004 compliance (rubber compounds: FDA 21 CFR 177.2600), certification is compound- and version-specific.
For how these standards map onto the SAE system, see EN 853 vs SAE J517; for the braid-class decision inside EN 853, see 1SN vs 2SN.
Reading a datasheet: a worked example
A DN 25 press feed line running 240 bar nominal with valve spikes to 300 bar at 70 °C oil: EN 853 2SN (165 bar at DN 25) is out immediately; EN 856 4SP (280 bar) fails on spikes; EN 856 4SH (380 bar) or R13 (345 bar) covers the duty with temperature-derating margin. That ten-minute table check is the entire difference between a five-year assembly and an unplanned shutdown.
Browse hydraulic hoses by construction and pressure class or run a search for EN 856 hose to compare datasheet values across the range.
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