BS ISO 7714:2018 pdf download – Agricultural irrigation equipment — Volumetric valves — General requirements and test methods Endurance tests performed in accordance with 7.8 are not required to be performed within the framework of the acceptance tests if the pattern approval test in Table 3 has been carried out for the same volumetric valve model, provided that the manufacturer has not introduced changes in the structure of the volumetric valve since the pattern approval test. 7.3.2 Thermal preconditioning Thermal preconditioning shall be performed before pattern approval tests. Subsequent thermal preconditioning shall be performed after substantial mechanical, structural, or material modification of the volumetric valve. Precondition the volumetric valve at a temperature of 50 °C to 55 °C for a period of 24 h using one of the following methods: a) immersing it in water; b) passing water through it at a sufficiently low flow rate to maintain the preconditioning temperature; c) placing it in an air oven. After thermal preconditioning, proceed with the tests. 7.4 Test of resistance to hydrostatic pressure Connect the valve inlet to a pressure source and increase the pressure gradually to 1,6 times the maximum working pressure. Maintain this pressure for 2 min. Perform the test procedure twice: once with the valve open and its outlet or outlets closed, and a second time with the valve closed and its outlet or outlets open. The volumetric valve shall withstand the test without incurring damage and without malfunctioning. No signs of leakage shall appear through the valve body, its joints or outlets. The test is applicable to plastic as well as metal valves. 7.5 Test of manual opening and closing 7.5.1 Non-serial volumetric valves 7.5.1.1 Open the volumetric valve per manufacturing instructions. Wait until the valve is fully opened. Manually close the valve per manufacturing instructions and do this and 7.5.1.2 for all open close scenarios of the valve. Ensure that the volumetric valve has fully closed. 7.5.1.2 Repeat the procedure with the hydrostatic pressure at the valve inlet at the maximum working pressure. 7.5.1.3 Perform the test three times. The valve shall open and close satisfactorily on each occasion. 7.5.2 Serial volumetric valves (single outlet, single outlet “skip over”, and dual outlet) 7.5.2.1 General Different manufacturers solve the same automation problems by different means. For this reason, tests of serial volumetric valves should be performed according to the manufacturer’s instructions. The tester should be satisfied that...
Download Address
Download