Pump cavitation: how ESA and ultrasound complement each other

The basic physics and six signs of cavitation are covered in "Pump cavitation: 6 signs". This article is about the practice of combining two methods that are often bought separately and used in isolation: SDT ultrasound and Artesis ESA.

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What each method measures

	SDT340 ultrasound	Artesis ESA
Signal	acoustics of collapse / turbulence	current, voltage, power, model
Sensor location	pump casing / suction	motor control cabinet
Strength	localisation and early acoustics	efficiency trend, load, electrical
Weakness	needs access to the machine	cannot say "where on the impeller"

Cavitation is both an acoustic and an energy phenomenon. One method confirms the other.

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Working sequence on site

1. Online ESA alert (e-MCM)

Artesis e-MCM captures:

• rising current at the same flow (efficiency drop);
• torque instability;
• a process status of "cavitation / operation away from BEP".

That gives a window of days to weeks, not seconds.

2. Targeted SDT ultrasound

An engineer with the SDT340 confirms:

• the characteristic "gravel" / hissing at the suction and volute;
• comparison with a healthy neighbouring pump;
• the dBµV trend after changing a valve position or tank level.

3. Maintenance action

Not "shut it down at any cost", but check:

• the level in the suction vessel / NPSHa;
• a blocked filter or strainer;
• VFD setting (speed too low);
• air ingress at the suction.

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Where the pairing is most valuable

• CHP plants — condensate, feedwater and circulation pumps.
• Water utilities — submersible stations (why vibration is weak there).
• Mining — slurry and tailings pumps.
• Chemicals — pumping aggressive media with variable viscosity.

Industry overview: Artesis by industry, SDT at CHP plants.

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A four-pump pilot

1. Fit e-MCM on four critical pumps.
2. Take an ultrasonic baseline under normal conditions.
3. On an amber ESA status — a mandatory SDT measurement the same day.
4. After 90 days — report how many times cavitation was caught before impeller erosion.

Motor pilot plan: e-MCM in 90 days. For a fleet without online monitoring, start with AMT Pro.

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Conclusion

ESA answers the question "this pump is running badly"; ultrasound answers "this is cavitation, here and now". Together they cut nuisance shutdowns and let you fix the cause (NPSH, filter, operating point) instead of just replacing the impeller.

See also: ESA vs vibration, SDT340 for hydraulics.