1. Hose size measurement: inner diameter, outer diameter, outer diameter of reinforcement layer, wall thickness, concentricity, thickness of inner and outer layers, inner diameter of assembly, the new national standard and ISO have added length and measurement point marks, and stipulated that no pipe joints and There are various methods of measuring the hose length of the fitting.
2. Hydraulic test Verification pressure test: Check whether the hose and assembly are leaking, deformed and damaged under the verification pressure for 30s-60s. Deformation test under pressure: keep for 1 minute under the specified pressure (working pressure proof pressure or other pressure lower than the proof pressure), measure the length and outer diameter change of the hose, as well as the twist angle and bending. Burst pressure test: measure the pressure when the hose bursts under the specified pressure increasing speed. Leakage test: Store for 5min under static pressure of 70% of the minimum burst pressure, repeat once to check whether there is leakage or damage. Since the test often uses water, the burst pressure and leakage pressure measured at room temperature may be slightly lower than the viscosity of the actual liquid used.
3. Low temperature flexural test Low temperature rigidity: the hose is clamped on a torsion wheel with a diameter of 12 times the inner diameter of the hose, and after being parked at low temperature for 6 hours, the torque measured when twisted 180° within 12s is the same as the torque measured at the standard temperature. ratio of torque. Bending at low temperature: The hose is clamped on a torsion wheel with a diameter of 12 times the inner diameter of the hose. After parking at low temperature for 24 hours, twist it 180° within 10s to check whether the inner and outer rubber is brittle and damaged. The easiest test to measure the low temperature brittleness of the hose is to bend the sample 90° at low temperature, or compress a section of the hose to 1/2 after freezing to see if it is brittle. Check to see if the sample is brittle.
4. Bending test: After bending the hose to a certain extent, measure the ratio of the minimum outer diameter of the bending part to the outer diameter before bending, the passing ability of the steel ball and the bending force when it is pressurized in the tube.
5. Suction flat test: vacuumize within 1min, keep it for 10min, roll it with a steel ball whose diameter is 0.9 times the inner diameter of the hose, and check the degree of collapse of the hose. Some standards use the rate of change of the outer diameter of the hose to indicate the degree of deformation of the hose.
6. Interlayer adhesion strength test: Most of the automobile hoses are braided hoses with a diameter of less than 50mm. The test usually uses a long sample with a width of 10mm or 25mm, and a ring with a width of 25mm is also used, which is peeled at 90° and the tensile speed is 25mm. /min.
7. Liquid wall penetration test: under normal pressure, connect the hose to a container filled with a certain liquid and seal the mouth of the container, place the test device horizontally, and then periodically measure the leakage of the entire test device caused by the liquid permeating outward through the hose. The mass changes to find the permeation speed of the liquid.
8. Volume expansion test: The rubber hose should not produce obvious volume changes under the pressure of the transmitted liquid. The method of measuring the volume expansion is to connect the rubber hose to a hydraulic source, and the other end and a measuring tube to measure the liquid volume after the expansion of the rubber hose. connected. Raise the pressure in the hose to the test pressure to expand the hose, then close the hydraulic source and open the valve connected to the measuring tube. At this time, the liquid in the volume expansion part rises into the measuring tube, and the expanded volume can be measured.
9. Cleanliness and extraction test: The fuel hose is usually injected with C liquid into the hose, emptied after being parked for 24 hours, and the inner wall is cleaned with C liquid. Collect the injected and rinsed C liquid, filter out the insoluble impurities, dry and weigh to obtain the weight of the insoluble impurities, and express the cleanliness by the number of impurities on the inner surface area of the unit hose or the maximum size of the impurities; the filtered solution is evaporated and dried , Weigh out the weight of soluble matter. The wax-like substance was extracted from the above-mentioned filtrate by evaporating and drying the above-mentioned filtrate with methanol, and the obtained methanol extract was evaporated to dryness, and the weight of the wax-like substance was weighed.
10. Salt spray test: Put the hose assembly in the salt spray formed by 5% sodium chloride aqueous solution at 35°C for 24 hours, and check whether the metal of the pipe joint is corroded.
