The basic principle of electrical impedance tomography (EIT) is similar to electrical resistance tomography (ERT) in that multiple measurements at the periphery of a process vessel or pipeline are taken and combined to provide information on the electrical properties of the process volume.
The key difference between electrical impedance tomography and ERT is that EIT combines resistance and reactance (the imaginary component related to phase shift in the measured signal). Generally ERT contains the essential information for process tomography measurements in conducting processes, however there are some systems (for example bio-related processes) where phase shift carries useful information – hence the benefit in utilising electrical impedance tomography.
The illustration above shows the behaviour of three different materials: (i) a pure conductor; (ii) a pure insulator; and (ii) a complex material which conducts and causes a phase shift (actually a banana!).
For more details about these instruments, or to discuss which type of tomography technology would be most appropriate for your process requirements, you can contact us directly via telephone on +44 (0) 161 832 9297, or fill out an Enquiry Form.