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
18.104.22.168 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 22.214.171.124 for all open close scenarios of the valve. Ensure that the volumetric valve has fully closed.
126.96.36.199 Repeat the procedure with the hydrostatic pressure at the valve inlet at the maximum working pressure.
188.8.131.52 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)
184.108.40.206 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 the test procedure presented to the tester by the manufacturer represents the serial function in question.
220.127.116.11 Test procedure Perform the same operations as for the non-serial volumetric valve, as described in 7.5.1, applying any necessary modifications in accordance with the manufacturer’s instructions. During the test, observe the orifice that transmits the hydraulic command to the next volumetric valve intended to be opened. When the tested volumetric valve is open, this orifice should freely pass water and when the tested volumetric valve is closed the orifice should close, or vice versa, depending on the logic of the hydraulic command.
7.6 Tests of accuracy
The type(s) of accuracy tests performed depend(s) on the class of volumetric valve. Volumetric valves with a cumulative volume counter (Class 1 and Class 2) shall be subjected to two tests of accuracy:
— accuracy of measurement (18.104.22.168);
— accuracy of dosing (22.214.171.124).
Volumetric valves without a cumulative volume counter (Class 3) shall be subjected to the test of accuracy of dosing only (126.96.36.199).
7.6.2 Flow rates and maximum permissible error for accuracy tests
188.8.131.52 Accuracy of measurement
Accuracy of measurement of the volumetric valve shall be tested at the following flow rates: q V1 ; 1,6q V1 ;
0,3q V3 ; q V3 ; and q V4 .
Determine the relative error (see also ISO 4064-2).
The relative error shall not exceed the following:
— for Class 1, ±2 % within the range of flow rates (q V1 to q V4 );
— for Class 2, ±4 % within the range of flow rates (q V1 to q V4 ).BS ISO 7714 pdf download.