Conventional pipe to soil potential measurements at existing test posts do not provide an indication of the true pipe to soil potential even a few metres away from the test post.
To enable a complete pipe to soil potential profile over the entire length of the pipeline a close interval survey is required with pipe to soil potentials recorded at approximately 1 to 2 metres.
Advances in technology have made it practical to carry out close interval surveys on buried structures.
It is, however not so easy to do them correctly, with maximum effectiveness, accuracy, and unambiguous data presentation.
The BAC Global Surveyor System has been purpose built by cathodic protection engineers who understand the requirements for effective field work and cathodic protection data accuracy.
The Surveyor System forms a complete package comprising:
- Datalogger synchronized to the current interrupters.
- Synchronised switchers to an accuracy of +/- 4 milliseconds/day
- Cable dispenser with automatic distance incrementing
- Special high insulation resistance lightweight cable (re-usable)
- Specialist data handling software. The surveyor Datalogger has the very highest specification available for field instruments.
- Input impedance switchable between 10 and 1000 megohms
- Common mode rejection: better than +/- 1mV for any dc input(operating range): better than 100 dB at 50-60 Hz for 10V ac input
- Normal mode rejection: better than 60 dB at 50-60 Hz for 10V ac input
- Voltage accuracy 0.1% FS
- Automatic optimum range selection for best voltage accuracy
- Four independent channels all synchronous (4 potential)
- All channels balanced input (No earth leakage problems)
- Automatically calibrates between each measurement
- Unique synchronization with switchers to +/- 4 milliseconds/day
- Unique adjustable delay before readings are measured in each switching period
- Adjustable length of sample period
- Adjustable sample frequency
- Distance is measured and recorded automatically as data is logged
- Operator code entry for features and geographic data
- Current measurement facility
- Memory equivalent to 750 Kb computer storage
- Full QWERTY keyboard