Ultrasonic Monitoring of Hydraulic Systems with the SDT 340

Hydraulic systems run under high pressure, are hidden from view, and are rarely checked until the first failure. That's exactly why they become a source of unplanned downtime and significant energy losses. The SDT 340 ultrasonic detector and SDT's Hydraulics pillar let you diagnose hydraulic condition without stopping equipment — based on data, not guesswork.

A problem you can't see

Hydraulic systems are among the most vulnerable and least monitored assets at industrial plants. Presses, mining equipment, drilling rigs, conveyor drives — all depend on hydraulics staying healthy. Yet at many companies, diagnostics still boils down to one approach: wait until something leaks or stops.

Here's why the standard approach doesn't work:

• Internal bypass through directional control valves isn't visible from the outside
• Pump cavitation develops gradually, with no external signs
• Seals degrade long before an oil stain appears on the floor
• A pressure gauge shows pressure — but doesn't tell you how much energy is being wasted

The result: equipment keeps running, but inefficiently — right up to the point of an emergency shutdown.

What ultrasound can hear

The SDT 340 is a professional ultrasonic detector operating in the 20–100 kHz range. This is exactly the range in which processes that precede hydraulic equipment failure generate signal — long before they can be detected visually or with standard instruments.

Internal valve bypass

When a directional control valve or relief valve starts passing oil internally, it creates a characteristic ultrasonic noise. Energy losses in the system can reach 15–25%, with no external signs at all.

The SDT 340 detects bypass before it becomes a performance problem — giving you time for a planned valve replacement instead of an emergency repair.

Pump cavitation

Cavitation destroys impellers and pump housings from the inside. In its early stages it has a clear acoustic signature — an ultrasonic detector "hears" it weeks before vibration or a pressure drop appears.

Catching it in time lets you fix the root cause (insufficient suction head, a clogged filter) without replacing an expensive pump unit.

Pipeline and fitting leaks

Oil loss through micro-cracks in hoses or loosened fittings generates an ultrasonic signal well before a visible leak appears. This is especially important for high-pressure piping, where a small leak quickly escalates into an emergency.

Seal degradation

A change in a seal's acoustic signature is an early sign of wear. The SDT 340 lets you track the trend: don't replace seals "on schedule" — replace them at the right moment, before they lose their seal.

How it works in practice

A technician with an SDT 340 and a set of contact and remote sensors surveys the hydraulic system without stopping equipment and without disassembly. The diagnostic process:

1. Route survey — contact and remote sensors at every point in the system
2. Data logging to the instrument's memory, tagged by point and time
3. Transfer to SDT Ultranalysis Suite software
4. Trend building and automatic alarms for deviations from the baseline

This means moving from "don't touch it while it's running" logic to "I know the condition of every component and make decisions based on data."

Who benefits from ultrasonic hydraulics monitoring

The method is especially effective at plants with:

• A large fleet of hydraulic equipment — presses, drilling rigs, lifting mechanisms
• High cost of downtime — mining, metallurgy, oil & gas
• Complex hydraulic circuits with many valves and directional control units
• Requirements to reduce energy and oil consumption

ROI: why it pays off

Problem detected	Losses prevented
High-pressure valve bypass	Oil and electricity savings + prevented actuator failure
Pump cavitation on mining equipment	Tens of thousands of dollars + several days of downtime
High-pressure pipeline leak	Emergency shutdown + environmental incident
Seal wear	Planned replacement instead of emergency repair

Experience at plants using the SDT 340 for hydraulics shows: the instrument pays for itself within the first 2–3 months of use.

Conclusion

Hydraulic systems don't forgive neglect — but they also don't require expensive permanent monitoring systems. The SDT 340 gives your maintenance team a tool that works where and when it's needed, speaking the language of data rather than guesswork.

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Consultation

KEG TRK is the official distributor of SDT International in Kazakhstan and the CIS. We're ready to run a demonstration on your equipment or help you build an ultrasonic hydraulics monitoring programme.

Contact us:

• 📞 +7 717 264 08 69
• ✉️ info@keg-trk.kz
• 🌐 www.keg-trk.kz