9 Surveying instruments and apparatus, measuring instruments, checking instruments, precision measuring apparatus, and levelling staffs, all of the aforesaid for monitoring, detecting and measuring fluid filling levels in the field of chemical productions, food production processes and oil productions; electrical indicators, electronic notice boards, and observation instruments, all for detecting and measuring fluid filling levels; temperature indicators for measuring fluid filling levels; marine depth finders for measuring fluid filling levels; water level indicators, quantity indicators, and electric monitoring apparatus, all for detecting and measuring fluid filling levels; fuel gauges for measuring filling levels of fuel; transmitters of electronic signals and data-processing apparatus for the application of sensors and monitors for detecting and measuring fluid software, for overfill prevention systems; optical condensers, electric capacitors, electrical boiler control instruments, and electrical heat regulating apparatus, all of the aforesaid for monitoring, detecting and measuring fluid filling levels in the field of chemical productions, food production processes and oil productions; computer programs recorded on data media, computer software recorded on data media, and computers, all of the aforesaid for the application of sensors and monitors for detecting and measuring fluid, for overfill prevention systems and sensors, for manhole monitors for measuring the entry of fluids into a manhole, and for monitoring and alarm systems for separators; data processing equipment, namely, couplers, transmitters of electronic signals, electro-dynamic apparatus for the remote control of signals; electric installations for the remote control of industrial operations, and sensors, all of the aforesaid for monitoring, detecting and measuring fluid filling levels, and level sensors for detecting and measuring liquid filling levels; sensors and sensing system for monitoring and measuring filling levels, flow sensors for measuring liquid levels, petrol station sensors for measuring fuel levels, level sensors for measuring layers in separators, overfill safety devices, namely, sensors and power controllers to prevent the overfill of oil tanks and process containers, control instruments, control apparatus, and measuring systems, all of the aforesaid to prevent the overfill of liquids