Hose assembly failure analysis

1, symptoms: hose inner tube is very hard, has been cracking.
   Analysis: temperature of the inner tube is easily precipitated plasticizer, which is a flexible hose can be a plastic material. Entrained gas oil oxidation allows the inner tube. Occur in the rubber products such oxidation reactions can be cured. Oxygen and temperature, will greatly accelerate the hardening of the hose tube. Occurred inside the inner tube cavitation also have the same effect.
2, symptoms: hose cracking internally and externally, but the elastic material is still soft at room temperature deflectable.
   Analysis: The likely reason is that the hose when the ambient temperature is very low deflection. Most standard hose is rated to -40 degrees, and some AQP hose rated temperature is -49 degrees, usually military hose rated temperature is -54 degrees, and some thermoplastic hose rated temperature is -54 degrees, poly four vinyl fluoride hose rated temperature is -73 degrees.
3, symptoms: hose rupture, hydraulic tube fittings peel the outer layer of wire reinforced rubber examination found that the entire length of the hose irregular wire breakage.
   Analysis: This indicates the pressure of the hose in a highly frequent fluctuations. SAE American Automobile Association, the two-story steel braided hose impact testing required at 133% of the recommended operating pressure of up to 200 000 cycles. About four-spiral hose SAE impact test requirements of up to 500 000 cycles. If the number of pulses within the extrapolation in a short time, more than one million times, the best choice for the enhancement layer wound hose.
4, symptoms: hose rupture, but not displayed on the entire length of the hose with multiple wire breakage. hydraulic hose sleeve May be more than one hose rupture.
   Analysis: This indicates that the pressure has exceeded the minimum burst strength of the hose. Recommended to use higher-strength hose, or hydraulic lines appear abnormally high pressure conditions can cause malfunction.