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Electrical Stability

Electrical Stability Tester (EST)

Fann Instrument Company introduces a new Electrical Stability Tester for use with oil-based drilling fluids. Mud engineers depend on the electrical stability test to monitor a fluid’s emulsion stability and oil-wetting capability. The new tester is simpler to operate and can be used
in the lab or in the field anywhere in the world.  

The Model 23E Electrical Stability Tester (EST) conforms to the test procedure described in API Recommended Practice 13B-2. It operates on external power or two nine volt batteries. The Model 23E is calibrated in peak volts which is the maximum voltage that the fluid
experiences between the two electrodes. Peak voltage may be converted to Root Mean Square (RMS) voltage by multiplying the peak voltage by 0.7071.


  • 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
EST Model 23E

Ordering Information

Part Number 102130986   Electrical Stability Tester


Output Frequency340 ± 2 Hz
Output wave formSinusoidal, <1% total harmonic distortion
Output voltage range0 to 2025 V ± 25 V peak to ground (1432 Volts RMS)
Breakdown peak output current61 micro-amps
Peak Volts readoutBacklit Digital LCD
Voltage ramp rate150 ± 10 V/second
Power supplyTwo 9-Volt alkaline batteries
100-240 VAC, 50/60 Hz, 10 watts
Battery lifeApproximately 250 tests
Dimensions8.3 X 5.1 X 2.8 in. (21 X 13 X 7.1 cm)
Complete Weight4 lbs (1.8 kg)
Probe and Cable length24 in (61 cm)
Probe Electrode Spacing0.061 in. (0.155 cm)
Operating temperature range.32° to 122°F (0° to 50°C)