"The high technical content of this project reflects the professional level and accomplishment of the instrument and deserves praise." At the production coordination meeting of Guangzhou Petrochemical Instrument and Control Center held on March 23, Project "won the fourth quarter of 2014, the best research project, the center's production technology director Zhao Li-feng said. At the end of last year, during the precautionary maintenance of two process control valves of 60KV103A and 60KV104B for three hydrogen-producing units, instrument staff of four workshops of the instrument control center discovered that the valve body is slow to act and there is a potential safety hazard of alarming for 8 seconds. If not resolved as soon as possible, will affect the normal operation of the system program, thus threatening the normal production of hydrogenation unit. As soon as possible to eliminate hidden dangers of production, four workshops to set up a technician, squad leader Yang Long led the research team to carry out "carpet" investigation. They repeatedly on the valve's reply switch, solenoid valves, air pressure valves and other accessories for inspection, testing, found no abnormal signs. Proper tackling team fool around, Yang Long in the PLC system through the input card tracking and monitoring, found that the pressure drop across the measurement circuit is too large. After further examination found that the measurement circuit pressure drop is too large due to the program control valve back switch fuse resistance caused by too much. After replacing the fuse, overtime alarm disappears. Finally, the research team to determine the fuse resistance is too large to cause the valve slow and overtime alarm "murderer." Find a problem and eliminate a hidden danger. After resolving the problem of the alarm of overtime of these two program control valves, Yanglong organizer inspected the fuses of the 88 program control valves in use by the device and found that the internal resistances of the fuses increased in varying degrees. To ensure safety, the workshop immediately developed a program of 88 program-controlled valves to replace fuses online. Recently, the fuse replacement is completed, the device control valve overtime alarm hidden dangers have been eliminated.