Pressure Transient Monitoring: How DR3704 Revealed a Hidden Pressure Spike

The $47,000-a-Week Scrap Problem

Our hydraulic press was cycling slower and slower, yet the pressure gauge on the panel consistently showed approximately 148 bar. Every part coming off the production line appeared to have the same problem: dimensions were outside specification, and the resulting scrap was costing approximately $47,000 per week.

At first, the pressure reading seemed to rule out a hydraulic pressure problem. We checked valves, seals, pumps, and other components, but nothing obvious explained the gradual deterioration in press performance. The installed gauge appeared to be working normally, and the SCADA system showed a relatively stable pressure trend.

The problem was that the pressure trend was only showing part of the story.

The actual problem was happening much faster than our existing monitoring system could reliably record. Short-duration pressure changes were occurring during the press cycle, but they were not visible in the historical SCADA data.

We needed a way to observe what was happening between the normal process measurements. That was when we started using pressure transient monitoring to investigate the problem.

Why SCADA Trends Can Miss Fast Pressure Transients

SCADA systems are excellent for monitoring process trends, but a trend display or historian does not necessarily capture every fast event occurring in the process.

When pressure data is recorded at relatively long intervals, a short-duration pressure spike can occur entirely between two recorded samples. In that situation, the historical trend may show a normal pressure value before the event and another normal value afterward, with little or no evidence that a significant transient occurred in between.

This was exactly the problem we faced.

Our hydraulic press appeared stable when viewed through the normal SCADA trend, but the actual pressure behavior during certain stages of the cycle was much more dynamic.

Hydraulic shock, valve switching, pressure relief events, cavitation, and other mechanical conditions can produce pressure changes that occur in milliseconds. If the measurement and recording system is not fast enough, these events can remain hidden until they begin affecting machine performance or product quality.

For troubleshooting applications, this creates a critical difference between monitoring the average process condition and capturing the actual pressure behavior.

The Hidden Pressure Transient

To investigate the problem, we installed a DR3704 Digital Pressure Gauge with Data Logging directly on the press manifold.

Instead of relying only on the existing SCADA trend, we used the DR3704 to collect pressure measurements at 10 ms intervals.

This provided a much higher-resolution view of the pressure behavior during the press cycle.

The results immediately changed our understanding of the problem.

The DR3704 revealed a recurring pressure spike of approximately 12 bar every time the pressure relief valve opened. The event was extremely short and was not clearly visible in the existing SCADA historical trend.

The pressure spike was creating hydraulic shock and disturbing the timing of the press cycle.

We finally had an explanation for the problem that the conventional monitoring system had failed to reveal.

10 ms Data Logging for Pressure Transient Monitoring

The most important capability for this investigation was the DR3704’s high-speed data logging.

With measurements recorded at 10 ms intervals, the instrument could provide a much more detailed record of rapid pressure changes than our existing historical trend.

This is where pressure transient monitoring becomes valuable.

Instead of asking only:

“What pressure is the system operating at?”

we could ask:

“What actually happens to the pressure during the entire machine cycle?”

That difference is critical when investigating hydraulic systems.

A stable average pressure does not necessarily mean a stable process. A system can maintain the expected operating pressure while still experiencing repeated pressure spikes, oscillations, or short-duration disturbances.

By recording pressure at high temporal resolution, the DR3704 gave us the data needed to identify those events.

Finding the Cause: Hydraulic Shock

Once we identified the recurring pressure spike, we focused our investigation on the pressure relief valve and the associated hydraulic circuit.

The timing of the transient matched the opening sequence of the relief valve.

The valve operation was producing a sudden pressure change, resulting in hydraulic shock that affected the press cycle.

We reprogrammed the relief valve sequence and added a dampening orifice to reduce the severity of the pressure transition.

After the modification, the previously observed pressure spike disappeared from the recorded pressure data.

More importantly, the press cycle returned to normal operating behavior.

The problem had not been a permanently incorrect pressure reading. It had been a fast pressure transient that conventional monitoring was not capturing clearly enough to diagnose.

From Hidden Data to a Practical Solution

The biggest benefit of the DR3704 was not simply that it recorded more data.

It allowed our engineering team to move from speculation to evidence.

Before the investigation, we were asking:

• Is the pump losing performance?
• Is a valve malfunctioning?
• Is there a seal problem?
• Is the pressure gauge inaccurate?
• Is the hydraulic circuit unstable?

After collecting high-resolution pressure data, we could ask a much more specific question:

Why does a 12-bar pressure spike occur when the relief valve opens?

That changed the entire troubleshooting process.

Instead of replacing components based on assumptions, we could identify the actual pressure behavior, correlate it with machine events, and make a targeted engineering adjustment.

SD Card Data Logging for Detailed Analysis

The DR3704 stores recorded pressure data on a standard SD card, with data available in CSV format.

This made it easy for our engineers to transfer the recorded data to a PC and analyze the pressure profile using standard spreadsheet or data-analysis tools.

For troubleshooting, this is particularly useful because engineers can compare pressure behavior with machine events, operating cycles, valve actions, and production results.

A recorded data file can also provide a useful engineering record for future maintenance and troubleshooting.

Instead of relying on a technician’s observation of a gauge at one moment in time, the team can review the actual pressure history captured during machine operation.

$500,000 in Avoided Scrap and Production Loss

After correcting the relief valve sequence and adding the dampening orifice, the pressure transients were significantly reduced.

The hydraulic press returned to its expected cycle behavior, and the scrap rate decreased by approximately 92%.

Over the following year, we documented approximately $500,000 in avoided scrap and lost production associated with the original problem.

The financial result was significant, but the engineering lesson was even more important.

The root cause had been difficult to identify because the pressure event was too short to appear clearly in the existing monitoring data.

Once we were able to see the transient, the solution became much more straightforward.

Continued Monitoring for Long-Term Reliability

After resolving the original problem, we continued using the DR3704 to monitor the hydraulic system.

This allowed our maintenance team to establish a pressure baseline and compare future measurements against the known operating condition.

The instrument’s ±0.25% FS accuracy provided reliable measurement data, while its large memory capacity supported longer recording periods.

The DR3704 also provides battery-powered operation with a stated battery life of approximately 3–5 years, depending on operating conditions and configuration.

Combined with its IP66 protection, this makes it suitable for industrial environments where continuous or periodic pressure recording is required.

Why Pressure Transient Monitoring Matters

Many industrial pressure problems are not caused by the steady-state pressure being too high or too low.

Instead, the problem can be caused by what happens during transitions.

A valve opens.

A pump starts.

A cylinder changes direction.

A relief valve activates.

A flow path changes.

Each event can produce a pressure response that may last only milliseconds.

If the measurement system only provides a low-resolution trend, these events can remain invisible.

Pressure transient monitoring provides a different approach: capture the pressure behavior during the event, identify the abnormal pattern, and correlate it with the machine’s operating sequence.

For hydraulic systems, this can be particularly valuable for investigating:

• Hydraulic shock
• Pressure spikes
• Valve switching problems
• Pump instability
• Cavitation-related pressure changes
• Cylinder movement issues
• Pressure relief events
• Intermittent hydraulic faults
• Unexpected machine cycle behavior

DR3704 Key Specifications

• High-resolution pressure data logging
• 10 ms recording interval
• Pressure transient monitoring capability
• ±0.25% FS accuracy
• SD card data storage
• CSV data export for PC analysis
• Large memory capacity for extended recording
• Battery-powered operation
• Approximately 3–5 year battery life, depending on operating conditions
• IP66 protection
• Suitable for industrial pressure monitoring and troubleshooting

When SCADA Data Is Not Enough

SCADA remains an essential tool for industrial process monitoring, but it is not always the best instrument for investigating very fast pressure events.

A normal SCADA trend can tell you that the system pressure is approximately 148 bar.

A high-resolution pressure recording can tell you that the pressure briefly jumped by 12 bar when a particular valve opened.

That additional information can be the difference between continuing to search for the problem and identifying the actual root cause.

The key is not to replace SCADA, but to use the right measurement tool for the problem being investigated.

SCADA provides the overall process picture.

High-speed pressure recording provides the detail.

Together, they can provide a much more complete understanding of dynamic hydraulic behavior.

Conclusion: See the Pressure Events Your SCADA Trend Misses

Our hydraulic press appeared to have a simple pressure problem, but the installed gauge and SCADA trend both suggested that the system was operating normally.

The real problem was hidden in short-duration pressure transients.

By installing the DR3704 and using pressure transient monitoring, we captured the pressure behavior at 10 ms intervals and identified a recurring 12-bar spike associated with the pressure relief valve.

After modifying the valve sequence and adding a dampening orifice, the transient was eliminated, the press returned to normal operation, and the scrap rate dropped by approximately 92%.

The resulting improvement helped us avoid approximately $500,000 in scrap and lost production over one year.

The lesson was simple:

If your process problem happens in milliseconds, your measurement system needs to be fast enough to see it.

Is your SCADA system showing the real pressure behavior—or only the pressure that remains after the transient has already disappeared?

Learn more about the DR3704 Digital Pressure Gauge with Data Logging for high-resolution pressure recording and industrial pressure transient monitoring.

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