37 Installation, maintenance, servicing and repair of industrial control sensors, namely optical, electronic, opto-electronic, photo-electrical, acousto-electrical, magnetic, inductive and capacitive sensors for use in monitoring the composition of gases and liquids and for monitoring meter levels and flows in industrial processes; installation, maintenance, servicing and repair of emission analyzing and control devices, namely flame ionization detectors, gas velocity meters, gas flow meters and ultrasound gas meters; installation, maintenance, servicing and repair of gas analyzers for use in industrial process measurements and for continuous emission monitoring; installation, maintenance, servicing and repair of analyzers for analyzing hydrocarbons, and dust concentration monitors; installation, maintenance, servicing and repair liquid analyzers and water analyzers; installation, maintenance, servicing and repair of liquid and gas level monitors for level monitoring in supply tanks and storage silos; installation, maintenance, servicing and repair of torsion meters for use in controlling the power of ship engines for optimization of engine torque in relation to ship velocity; installation, maintenance, servicing and repair of gas and liquid leak detectors for detection of leaks in gas and liquid pipelines; installation, maintenance, servicing and repair of electrical conductivity meters, spectroscopic meters and photo meters; and installation, maintenance, servicing and repair of computer hardware systems and computer data memories for use with emission monitoring systems in power stations