The Fann Electrical Stability Tester, Model 23E is a portable instrument that measures the electrical stability (ES) of an oil-based drilling fluid. The EST conforms to the electrical stability test procedure that is described in API Recommended Practice for Field Testing Oil-based Drilling Fluids, API RP 13B-2. The EST includes the meter, electrode probe, 2 batteries, a power cord, 2 calibration standards, and a plastic carrying case.

The drilling fluid’s electrical stability is measured by applying a steadily increasing sinusoidal alternating voltage across a pair of parallel plate electrodes (probe). This probe is submerged in the oil-based drilling fluid. It is recommended that you record several measurements to establish a trend. These measurements will reflect an accurate condition of the drilling fluid and provide a basis for drilling fluid treatments.



  • Internal power supply and built in AC power plug allow universal operation

  • Power requirements - 100 to 240 VAC, 50/60 Hz, 10 watts

  • Portable operation on two (2) nine volt batteries

  • Self-calibration for immediate performance checks

  • Large backlit display is easy to read, even in low light

Ordering Information

Part No. 102130986 — Electrical Stability Tester

EST includes:

2 X 9 Volt Batteries, Power Cord, EST Probe with Cable, Calibration Standard, High Range, Calibration Standard, Low Range Optional, Calibration Standard Set


Are you interested?

Talk with a Fann expert

Contact us