How to choose the right Sprial Hdraulic Hose?
How to choose the Right Hydraulic Hose for Construction Machine?
When selecting steel wire spiral hydraulic hoses, a comprehensive evaluation based on the following core
dimensions is necessary to ensure a precise match between hose performance and operational requirements:
I. Pressure Rating Matching: Safety Redundancy Design
Working Pressure Selection
The rated working pressure of the hose must be ≥ 1.25 times the maximum working pressure of the system to
withstand impact loads. For example, when the system pressure is 40MPa, a hose with a rated pressure ≥ 50MPa
should be selected (e.g., type 4SP-32-32, rated at 32MPa, requires upgrading to a higher specification).
The burst pressure is typically 4 times the working pressure
4-layer steel wire spiral: High-pressure applications (e.g., mine supports, pressure up to 70-100MPa).
6-layer steel wire spiral: Ultra-high-pressure environments (e.g., deep-sea operations, pressure ≥ 140MPa).
II. Media Compatibility: Chemical Protection is Key
Petroleum-based Media
Mineral oil, hydraulic oil, fuel oil: A nitrile rubber (NBR) inner layer is required, such as the 4SP/4SH series,
offering excellent oil resistance.
Lubricating oil: If containing extreme pressure additives, verify that the hose passes the ASTM D471 oil swelling
test (volume change rate ≤10%).
Water-based Media
Emulsions, water-based hydraulic oil: A hydrogenated nitrile rubber (HNBR) or neoprene rubber (CR) inner layer
is required to prevent hydrolytic aging.
Seawater environment: An outer layer with salt spray corrosion resistant formulation is required, such as DIN
20023 standard hoses.
Special Media
High-temperature media (e.g., hot oil): A fluororubber (FKM) inner layer is required, with temperature resistance
up to 220℃.Corrosive media (e.g., acids): An outer polytetrafluoroethylene (PTFE) sheath is required, or SAE 100
R14 hoses should be selected.
2. Outer Diameter and Assembly
The outer diameter must be smaller than the equipment mounting hole diameter, leaving a 0.5-1mm gap to prevent
friction.Bending radius ≥ minimum bending radius of the hose (e.g., minimum bending radius of 260mm for type
4SP-16-50) to avoid breakage of the skeleton layer.
Length Customization
Total length = equipment interface spacing + bending allowance (usually 5%-10% of the interface spacing).
Avoid excessive length leading to loosening friction, or excessive short length causing tensile breakage.
Temperature Range
Low Temperature Environments (below -40℃): Low-temperature nitrile rubber (LT-NBR) is used to prevent the rubber
compound from hardening and cracking.High Temperature Environments (above 120℃): Silicone rubber (VMQ) or
fluororubber (FKM) outer layer is used.
Mechanical Protection
Outdoor Environments: UV anti-aging agents are added to the outer layer to prevent UV degradation.
Areas with Frequent Friction: A braided steel wire sheath or spring protective sleeve is used, such as DIN 20022 standard hoses.
Explosion-proof and Anti-static
Flammable Scenarios such as Coal Mines: MT/T 98-2006 explosion-proof certification is required; the conductivity of the
outer layer must be ≤10⁶Ω/m.
Static Sensitive Environments: Conductive carbon black is added to the inner layer; the resistance value must be ≤10⁶Ω.
3. Cost and Lifespan: Overall Economic Efficiency
Initial Cost
Imported brands are typically 1.5-2 times more expensive than domestic brands, but their pulse lifespan may be extended
by 30%-50%.
Maintenance Cost
Hydraulic Hose with good flexural strength (such as 6-layer steel wire spiral type) can reduce replacement frequency and lower
downtime losses.Anti-friction sheaths can extend the lifespan of the outer rubber layer by 2-3 times, but increase initial costs by
10%-15%.
Total Cost of Ownership (TCO)
Calculation Formula: TCO = Initial Cost + (Replacement Frequency × Cost per Replacement) + Downtime Losses.
Example: For high-pressure mine support hoses, although imported brands have higher initial costs, their TCO may be 20%
lower than domestic solutions.
