求SAE标准( 三 ) _SAE

4.2.3.4 Repeat the preceding step two times, so the amount of brake fluid or water in the buret will be the total of the three expansions. Measure this buret reading to the nearest 0.05 cm3.
4.2.3.5 The volumetric expansion is calculated by dividing the buret reading by three and subtracting the calibration factor. This figure divided by the free length in meters (feet) will give the volumetric expansion per meter (feet) of hose.
4.2.3.6 Readjust the brake fluid or water level in the buret to zero as previously stated and repeat the procedure to obtain the expansion at pressures of 10.3 MPa +0, ?0.14 MPa (1500 psi +0, ?20 psi) and 20 MPa +0, –0.14 MPa (2900 psi +0, –20 psi.) If the pressure in the hose should inadvertently be raised to a value above that specified, but not above 24 MPa (3500 psi), completely release the pressure and allow the hose to recover for at least 15 min and then repeat the test. If the hose was subjected to a pressure above 24 MPa (3500 psi), repeat the test using a new brake hose. If at any time during the test an air bubble flows out of the hose, repeat the test after allowing at least 3 min for the hose to recover.
4.2.3.7 Test Apparatus—Test apparatus shall consist essentially of the following:
a. A source for required fluid pressures, test fluid consisting of brake fluid or water without any additives and free of air or gas bubbles.
b. A reservoir for pressure gages, fittings where the hose assembly may be mounted vertically for application of pressure under controlled conditions.
c. A graduated buret with 0.05 cm3 increments for measuring the volume of liquid corresponding to the expansion of the hose under pressure.
d. Plumbing hardware as required.
All piping and connections shall be smooth bore without recesses or offsets so all air may be freely removed from the system before running each test. Valves shall be capable of withstanding pressures involved without leakage. See Figure 2.

4.2.3.8 Calibration of Apparatus—The apparatus shall be tested prior to use to determine its calibration correction factors. These correction factors should be established at pressures of 6.9, 10.3, and 20 MPa (1000, 1500, and 2900 psi) using an assembly, which shall consist, for example, of 1.52 mm (0.060 in) minimum wall, hydraulic steel tubing with a free length of 305 mm ± 6 mm (12 in ± 0.2 in), and 6.3 mm (0.25 in) outside diameter. All fittings and adapters used in testing of the assembly shall be in this system. This may require the attachment of the tubing to the brake hose fittings in the case of special end configurations. The calibration correction factors shall be subtracted from the expansion readings obtained on the test specimens. The maximum permissible calibration correction factor shall be 0.08 cm3 at 10.3 MPa (1500 psi).
4.2.4 BURST STRENGTH TEST—Connect the specimen to the pressure system and fill completely with water or SAE Referee Brake Fluid RM 66-05, allowing all air to escape. Removal of air bubbles may be facilitated by moving the hose back and forth. Apply 27.6 MPa +0, ?1.4 MPa (4000 psi +0, ?200 psi) pressure at the rate specified in 4.2.4.1 and hold for 2 min +0, ?10 s. At the expiration of this hold period, increase the pressure at 172.5 MPa/min ± 69 MPa/min (25 000 psi/min ± 10 000 psi/min) until the hose bursts. Read the maximum pressure obtained on the calibrated gage to the nearest 1 MPa (100 psi) and record as the bursting strength of the hose assembly.
4.2.4.1 Test Apparatus—The apparatus shall consist of a suitable pressure system where hose is connected so that controlled and measured fluid pressure may be applied internally. The pressure shall be obtained by means of a hand- or power-driven pump or an accumulator system and it shall be measured with a calibrated gage. Provision shall be made for filling the hose with water or brake fluid and allowing all air to escape through a relief valve prior to application of pressure. This is important as a safety measure. The hold and burst pressures shall be applied at a rate increase of 172.5 MPa/min ± 69 MPa/min (25 000 psi/min ± 10 000 psi/min). Since this type of hose withstands a minimum bursting pressure of 49 MPa (7000 psi) for 3.2 mm (1/8 in) and 34.5 MPa (5000 psi) for 4.8 mm (3/16 in), care must be taken that all piping, valves, and fittings are sufficiently rugged and adapted to high-pressure work. The apparatus described for the expansion test may be used when it conforms to these requirements.

求SAE标准( 三 )

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