A Sensor Rated for 2000 bar – But Is It Designed to Work There?

“If the sensor is rated for 2000 bar – it’s allowed to operate at 2000 bar.”

It sounds correct, logical, and even supported by the datasheet.
And yet, this is one of the most problematic myths when selecting pressure sensors for high-pressure applications.

The reason is simple:
A rating is a safety limit – not an operating point.

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Why Is This Myth So Persistent?

Because in most cases:

• The sensor really does survive the pressure

• The measurement initially looks correct

• Initial tests pass successfully

But over time, symptoms begin to appear:

• Slow, unexplained drift

• Gaps between static and dynamic measurements

• Instability under cyclic operation

• “It worked for a year, and then it started acting up”

At that point, teams start looking at calibration, electronics, EMI –
when in fact, the problem started much earlier: sensor selection.

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So How Should You Choose a Pressure Sensor Above 1000 bar?

If the rating alone is not enough, different questions must be asked.
Not about the number at the edge – but about how the system actually operates.

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5 Questions You Must Ask Before Selecting a High-Pressure Sensor

1. How long does the sensor operate above 80% of its range?
A brief excursion to the limit is completely different from continuous operation near full scale.

2. Is the pressure static or cyclic?
Load cycling is a major fatigue factor, even if each cycle is “within the rated range”.

3. Is accuracy required over time, or only at the beginning of life?
Cumulative drift does not appear on day one.

4. Are there short pressure overshoots?
Short peaks, even if undocumented, significantly affect sensor lifetime.

5. Is the sensor a general-purpose device – or dedicated for high pressure?
This is usually the question that answers all the others.

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This Is Where Engineering Separation Comes In

This is exactly why manufacturers separate between:

• General-purpose pressure sensors suitable for most applications

• Dedicated high-pressure sensors designed to operate well away from the edge

For example, at Variohm, this separation is reflected between the general EPT3100 series
and the dedicated high-pressure EPT31HP series.

Not as an upgrade.
As an engineering design decision.

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Bottom Line

If the sensor is operating at the edge,
it is probably not the right sensor.

Correct selection for high-pressure applications does not start with the maximum number,
but with where the sensor can operate comfortably over time.

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Pressure Sensor Selection in High-Pressure Systems

In high-pressure systems, pressure sensor selection is often based on a single number:
the maximum value listed in the datasheet.

In practice, this is one of the main causes of design errors in test systems, hydraulics, and heavy industrial equipment.

The critical difference is not between 1500 and 2000 bar –
but between Rated Pressure and Operating Pressure.

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Rated Pressure vs Operating Pressure – The Distinction Most Projects Miss

Rated Pressure defines the safety limit of the pressure sensor –
the pressure it can withstand without immediate failure.

Operating Pressure, on the other hand, defines the zone in which:

• Accuracy is maintained

• Drift is minimized

• Reliability remains stable over time

In systems where the sensor operates close to its rated pressure, even if it is “on paper” within limits, familiar symptoms begin to appear:

• Pressure sensor drift

• Measurement inconsistency

• Frequent recalibration

• Loss of confidence in the results

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Why Do High-Pressure Sensors Fail Only After Months?

Failures in high-pressure sensors are almost never dramatic.
They develop gradually:

• Prolonged operation above 80% of full scale

• Cyclic pressure loads

• Short, undocumented overshoots

• The combination of high pressure and temperature

This is exactly why a dedicated high-pressure transducer differs from a general-purpose pressure sensor – even if both are “rated” to the same value.

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ENGINEERING NOTE

EPT3100 vs EPT31HP – An Engineering Perspective

The EPT3100 series is intended for general industrial applications, where pressure remains within a broad operating envelope with reasonable design margins.

In applications where:

• Pressure is very high

• Operation occurs close to full scale

• Load cycling is present

• Long-term stability is required

A dedicated high-pressure sensor is required.

The EPT31HP series was developed specifically for this point, featuring:

• Mechanical design optimized for high pressures

• Nominal operation well away from the edge of the range

• Improved stability over the product lifetime

The separation between the series is intended to prevent situations where a sensor “meets the requirements on paper”
but in practice operates under constant mechanical stress.

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TECHNICAL CASE STUDY

From a General-Purpose Sensor to a Dedicated High-Pressure Sensor

Background:
A hydraulic test system operating at pressures up to 1800 bar, with cyclic loading.

Initial Setup:
Use of a general-purpose pressure sensor rated to 2000 bar.
The system performed correctly at the beginning.

Observed Issue:
After several months of operation:

• Measurement drift

• Discrepancies between parallel sensors

• Reduced confidence in test results

Analysis:
The sensor operated most of the time above 85% of its range under cyclic loads.
On paper – within the rating.
In practice – at the edge of the operating envelope.

Solution:
Migration to a dedicated high-pressure sensor from the EPT31HP series,
shifting the operating point into the central, stable region of the range.

Result:

• Long-term measurement stability

• Elimination of frequent recalibration

• Improved overall system reliability

Conclusion:
The issue was not sensor quality – it was sensor selection.

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Pressure Sensor Selection: General Series vs Dedicated High Pressure

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Engineering Summary

EPT3100
Suitable when the operating point is clearly within the recommended operating zone.

EPT31HP
Selected when the operating point approaches the rated limit and the system must remain stable and reliable over time.

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FAQ – Selecting High-Pressure Sensors (EPT3100 / EPT31HP)

If a sensor is rated for 2000 bar, why not operate at 2000 bar?
Because the rating defines a safety limit, not a continuous operating zone. Prolonged operation at the edge increases drift, material fatigue, and reduces reliability.

What is the practical difference between a general-purpose sensor and a dedicated high-pressure sensor?
A general-purpose sensor is designed to operate comfortably away from the limit.
A dedicated high-pressure sensor is designed so that even at high pressures, the operating point remains in a stable region.

When is EPT3100 the right choice?
When the operating point is clearly within the recommended zone, with reasonable design margin and without severe cyclic loading.

When must you move to EPT31HP?
When:

• Pressure is close to full scale

• High-pressure cyclic operation is present

• Long-term stability and accuracy are required

• The system is a test bench or validation setup

Is EPT31HP more accurate than EPT3100?
Not necessarily in the datasheet accuracy figure, but in long-term stability under high-pressure operating conditions – which is the critical difference.

Can you “upgrade” from EPT3100 to EPT31HP without system changes?
In many cases yes, but pressure range, output, connection, and configuration must be verified. The difference lies mainly in the operating envelope, not integration.

What happens if you operate above 80% of the range for long periods?
Usually not immediate failure, but:

• Slow drift

• Inconsistency

• Frequent recalibration

• Reduced confidence in the measurement

Why did the manufacturer split the series instead of keeping a single model?
To prevent design and ordering mistakes and to clearly indicate when a pressure sensor is no longer “standard” but requires a dedicated solution.

How can you be sure what fits your project?
Not by the maximum number alone, but by:

• The actual operating point

• Time spent near the limit

• Load characteristics

• Long-term stability requirements