What tests do hydraulic hoses need to undergo before leaving the factory?
1. Salt spray test
Testing method: Salt spray testing is an accelerated testing method that first atomizes a certain concentration of salt water and then sprays it into a closed constant temperature box. By observing the changes in the hose joint after being placed in the constant temperature box for a period of time, the corrosion resistance of the joint can be reflected.
Evaluation criteria: The most common evaluation criterion is to compare the time it takes for oxides to appear on the joint with the expected value during design to determine whether the product is qualified.
2. Blasting test
Testing method: Burst testing is a destructive test that typically involves uniformly increasing the pressure of a hydraulic hose assembly that has been newly compressed for 30 days to 4 times the maximum working pressure, in order to determine the minimum burst pressure of the hose assembly.
Evaluation criteria: If the test pressure is below the minimum burst pressure and the hose has already experienced phenomena such as leakage, bulging, joint popping, or hose bursting, it is considered unqualified.
3. Low temperature bending test
Testing method: Low temperature bending test is to place the tested hose assembly in a low-temperature chamber, maintain the temperature of the low-temperature chamber constant at the minimum operating temperature specified for the hose, and keep the hose in a straight line state. The test lasts for 24 hours. Subsequently, a bending test was conducted on the core shaft, with a diameter twice the minimum bending radius of the hose. After the bending was completed, the hose was allowed to return to room temperature, and there were no visible cracks on the hose. Then, a pressure test was conducted. At this point, the entire low-temperature bending test is considered complete.
Evaluation criteria: During the entire testing process, the tested hose and related accessories should not rupture; When conducting the pressure test after restoring room temperature, the tested hose must not leak or rupture.
4. Pulse testing
Testing method: Pulse testing of hydraulic hoses is a predictive test for hose life. The experimental steps are as follows:
* First, bend the hose assembly into a 90 ° or 180 ° angle and install it onto the experimental device;
* Inject the corresponding test medium into the hose assembly, and maintain the medium temperature at 100 ± 3 ℃ during high temperature testing;
* Apply pulse pressure to the interior of the hose assembly, with a test pressure of 100%/125%/133% of the maximum working pressure of the hose assembly. The test frequency can be selected between 0.5Hz and 1.3Hz. After completing the corresponding standard specified number of pulses (Parker conducted 2000000 cyclic pulse tests on its GlobalCore 787 and 797), the experiment is completed.
There is also an upgraded version of pulse testing – flex pulse testing. This test requires fixing one end of the hydraulic hose assembly and connecting the other end to a horizontal moving device. During the test, the movable end needs to move back and forth at a certain frequency.
Evaluation criteria: If there is no failure of the hose assembly after completing the required total number of pulses, it is considered to have passed the pulse test.
