A lot of pneumatic diaphragm valves （lose-air to close） made by SEREG is used in Dayabay Nuclear Power Station. Because of their stable performance

these valves are used as isolation valves in the system of higher nuclear level. In order to track the operating conditions of equipment

two sets of advanced tool

FRATOL Ⅲ H

have been purchased for testing said valves. The test can be done on site without dismounting the valve. According to the measured mechanical parameters

such as the initial drop-seat load

the packing load

and the performance of spring washers

the valve state can be diagnosed and adjusted properly. In addition

the defects of spring washers

diaphragms and O-rings can be also checked with the said tool

enabling the replacement of them to be timely realized. In other words

the preventive maintenance can be implemented on the basis of reducing unnecessary disassembly.