How Do You Know If a Liquid Cooling System Is Really Working? Pressure and Temperature Tell the Story

In High-Power Systems, Cooling Is No Longer Just About Fans and Heat Sinks

In high-power systems, cooling has long moved beyond traditional fans and heat sinks.

AI servers, radar and electronic warfare systems, mission computers, power converters, batteries, and electric propulsion systems generate enormous amounts of heat in increasingly compact spaces. As power density continues to rise, so does the use of Liquid Cooling – systems in which coolant transfers heat away from critical components to a heat exchanger, radiator, or central cooling unit.

But this raises an important question:

How do we know that the liquid cooling system is actually working as designed?

Temperature measurement alone tells only part of the story.

If the temperature rises, we know something is wrong. But in some cases, by the time a thermal problem becomes apparent, it may already be affecting the electronics.

Changes in pressure, on the other hand, can provide valuable information about what is happening inside the cooling loop before the system reaches a critical temperature.

A degrading pump, partial blockage, clogged filter, coolant loss, or a change in flow resistance can all affect the system’s pressure profile.

This is why advanced cooling systems should not ask only:

“How hot is the coolant?”

They should also ask:

“What is the pressure, and is it behaving as expected?”

This is where accurate Pressure Sensors and Pressure Transducers, such as the wide range of solutions offered by Variohm, become an important part of cooling system monitoring.

Pressure and Temperature – Two Sides of the Same Cooling System

Consider a simple liquid cooling loop.

Coolant leaves the pump, flows through a Cold Plate or heat exchanger attached to a heat-generating component, absorbs thermal energy, and then returns to the cooling system.

Within this loop, we want to understand at least two key parameters:

Pressure – Is the pump producing the expected pressure, and is there any unusual resistance to flow?

Temperature – How much heat has the coolant absorbed, and what is happening to the thermal condition of the system?

Each measurement is valuable on its own.

But when pressure and temperature are monitored together – and in some applications even at the same measurement point – they can provide a much more useful picture of cooling system behavior.

For example, a temperature increase while pressure remains stable may indicate a very different condition from a temperature increase accompanied by a significant pressure change.

In a critical system, that can be the difference between knowing:

“The system is getting hot.”

and understanding:

“Why is the system getting hot?”

That information can then be used for cooling system control, condition monitoring, fault detection, and system protection.

For applications where both parameters are required, Variohm Combined Pressure and Temperature Transducers provide pressure and temperature measurement within a single sensor assembly, helping reduce installation complexity while providing two critical measurements from the cooling system.

Figure 1: Pressure and temperature together provide a more complete picture of liquid cooling system health.

When Temperature Rises, the Problem May Have Started Earlier

Temperature is one of the most important parameters in any cooling system, but it does not always tell us why a change has occurred.

Suppose the coolant temperature begins to rise. The reason may be straightforward – the thermal load has increased. But it could also be related to reduced pump performance, a partial blockage, coolant loss, or another change within the cooling loop.

This is where pressure monitoring adds another layer of information.

By monitoring Pressure and Temperature together over time, engineers can evaluate not only whether a parameter has crossed a predefined limit, but also whether the behavior of the cooling system itself has changed.

For example, a system that has operated for a long time with a consistent pressure and temperature profile may gradually begin to deviate from that baseline. This can provide an indication that something within the cooling loop is changing, even while temperatures remain within their allowable range.

It is important to remember that a Pressure Sensor is not a Flow Meter. A pressure change alone cannot definitively identify a specific fault. Pressure can change for many reasons and should always be evaluated together with other system data.

But this is precisely where combining measurements becomes valuable.

Instead of waiting for an alarm that says:

“The temperature is too high.”

we can start asking an earlier and more useful question:

“Is the liquid cooling system still behaving as expected?”

For this type of monitoring, Variohm Pressure Transducers offer a wide range of pressure ranges, mechanical configurations and sensor technologies, allowing the pressure measurement to be matched to the actual requirements of the cooling loop.

In a Data Center, It Is About Availability. In a Defense System, It Can Be About the Mission.

This challenge is not limited to AI servers and data centers.

The same principle applies wherever high-power electronics depend on a liquid cooling system.

In a Data Center, these may be GPUs, processors and AI accelerators connected to Cold Plates and a CDU.

In Radar and Electronic Warfare systems, they may be RF amplifiers and high-power electronic modules operating under demanding loads.

In a military vehicle, they may include mission computers, power converters, electric propulsion systems or energy storage systems.

And in a UAV or UGV, where space and weight are limited, the cooling system itself must be as compact and efficient as possible.

In all these applications, the basic chain remains the same:

Heat is generated -> the coolant absorbs it -> the pump circulates the coolant -> the heat is transferred away.

A problem at any point in this chain may eventually appear as an increase in temperature.

The more interesting question is whether Pressure Sensors can help identify a change in cooling system behavior earlier, before temperature itself becomes the critical problem.

What If Pressure and Temperature Could Be Measured at the Same Point?

Traditionally, pressure and temperature can be measured using two separate sensors.

But there is another option: a Combined Pressure and Temperature Transducer.

Variohm offers combined pressure and temperature sensors designed to provide both measurements from a single sensor assembly and measurement location.

This approach can provide several advantages, particularly where installation space is limited: fewer installation points, less wiring, fewer penetrations into the cooling circuit, and a reduced component count.

There is also an important measurement advantage.

When pressure and temperature are measured at the same physical location, the control system receives two parameters describing conditions at the same point and at the same time.

For compact, mobile and high-power systems, this can be particularly valuable.

The Variohm EPTTE3100, EPTTE1400, EPTT5100 and EPTTE5100 families provide different options for combined pressure and temperature measurement, allowing engineers to select a solution according to pressure range, temperature measurement requirements, size, mechanical interface and electrical output.

In other words, instead of adding another sensor simply because another parameter is required, it may be possible to turn a single measurement point into a more complete Pressure + Temperature monitoring point.

Figure 2: A combined pressure and temperature transducer enables both parameters to be measured at the same point in the system, reducing the number of sensors and installation points.

Fewer Sensors, Fewer Connections, Fewer Potential Failure Points

In a liquid cooling system, every additional component matters.

An additional sensor requires another installation point, another mechanical connection, and additional wiring. In compact, high-density systems, installation space itself can become a valuable resource. In mobile applications, weight and the number of connections also become important design considerations.

This is why a combined Pressure + Temperature Transducer is more than simply a convenient way to obtain two measurements.

It can also help simplify the overall system architecture.

Instead of installing a pressure sensor at one location and a temperature sensor at another, a Variohm Combined Pressure and Temperature Transducer can, where appropriate, measure both parameters from the same physical measurement point.

This becomes particularly useful when measurements are required at several locations throughout the cooling loop, for example before and after a heat-generating component, or at key points around the pump and heat exchanger.

The result is more than just system protection. It can help engineers build a clearer picture of what is happening to the coolant as it moves through the liquid cooling circuit.

Beyond Data Centers: Liquid Cooling in Defense and High-Power Electronics

The rapid growth of AI has made Liquid Cooling for Data Centers a major engineering topic, but the underlying thermal challenge extends far beyond server racks.

In a radar system, for example, RF modules and Power Electronics can generate significant thermal loads. A military vehicle may simultaneously operate mission computers, communication systems, power converters, EW systems and other high-power electronics, often under demanding environmental conditions.

Electric propulsion systems and batteries also require effective thermal management. In UAVs and other compact platforms, the same challenge must be solved with even tighter restrictions on available space and weight.

In all these applications, the objective is not simply to maintain the coolant at a particular temperature.

The real objective is to protect the critical system that depends on that cooling loop.

If the cooling circuit gradually loses its ability to remove heat, the electronics will eventually be affected.

In a Data Center, the result may be reduced performance, thermal throttling or equipment shutdown.

In a defense application, the consequence can be very different: a mission-critical system may no longer be able to maintain the required performance while the mission is still underway.

For this reason, cooling system pressure monitoring can become an important part of the overall system Health Monitoring strategy.

From Overpressure Protection to Cooling System Health Monitoring

There is an important difference between using a Pressure Sensor simply to trigger an alarm when a limit is exceeded and using pressure data to identify a developing trend.

Consider a system that repeatedly operates under a similar mission or load profile.

Over time, engineers may notice that under the same operating conditions, coolant temperature is slightly higher while the pressure at a particular point in the cooling circuit has also shifted from its normal behavior.

Neither value necessarily needs to be outside its permitted range.

But the change itself may be significant.

This is the basis of Condition Monitoring: rather than asking only whether the system has already exceeded a limit, pressure and temperature data can be monitored for changes that may justify investigation before a more serious cooling problem develops.

This is where selecting the right Variohm Pressure Transducer becomes important. The sensor is not simply there to detect maximum pressure. Its measurement range, accuracy, materials, mechanical interface, electrical output and installation location all determine how useful that pressure information will be.

And when both Pressure and Temperature data are available, the control system has a richer set of information on which to base monitoring, diagnostics and protection decisions.

Figure 3: Pressure monitoring in a liquid cooling circuit can reveal changes in system behavior and provide early indication of pump degradation, blockages, leaks, or changing flow conditions.

So What Does Pressure Actually Tell Us?

In a liquid cooling system, a Pressure Sensor is not there simply to provide an overpressure alarm.

Pressure is one of the key parameters that can help us understand how the hydraulic circuit is behaving.

This is why Coolant Distribution Units (CDUs) often monitor pressure at different points in the cooling loop. For example, pressure measurements upstream and downstream of the pump can provide real-time feedback for coolant and thermal management.

The real value is not necessarily a single pressure reading, but how pressure behaves over time and at different points throughout the system.

A gradual decrease in pressure may justify checking pump performance, coolant level, or the possibility of a leak.

An increasing pressure difference between two points may indicate increased resistance to flow, for example due to a filter or passage that is gradually becoming restricted.

Unstable pressure may indicate abnormal behavior within the cooling circuit that requires further investigation.

None of these conditions provides a diagnosis on its own. A Pressure Sensor cannot tell us, “the filter is clogged” or “the pump is about to fail.”

What it can do is provide the control system with valuable physical data that helps identify when the cooling circuit is no longer behaving as it did before.

This is where accurate and correctly selected Variohm Pressure Transducers can become much more than simple protection devices. They can become part of the monitoring strategy for the entire liquid cooling system.

Sometimes the Pressure Difference Tells the More Interesting Story

Suppose we install one Pressure Sensor upstream of a component and another downstream.

Now we are not simply looking at two independent pressure readings. We can also monitor the Pressure Drop between those two points.

If the pressure differential across a component changes over time under comparable operating conditions, it may indicate that the hydraulic resistance of that part of the system has changed.

The same principle can be applied across filters, Cold Plates, heat exchangers, pumps, and other components within the cooling loop.

This brings us back to one of the central ideas of this article:

Temperature tells us what is happening thermally. Pressure helps us understand what is happening inside the circuit responsible for carrying that heat away.

In a critical liquid cooling system, we want to understand both.

Not Every Liquid Cooling System Needs the Same Pressure Sensor

This is where proper sensor selection becomes important.

A Pressure Transducer designed for a hydraulic system operating at hundreds of bar is not necessarily the right choice for a liquid cooling circuit operating at much lower pressures.

And pressure range is only one part of the selection process.

Engineers also need to consider wetted materials and coolant compatibility, media temperature, electrical output, pressure port, sealing, sensor dimensions, and the environmental conditions in which the system will operate.

This is one of the key advantages of the Variohm Pressure Sensor portfolio: instead of forcing one sensor architecture into every application, engineers can select a Pressure Transducer that matches the actual requirements of the cooling system.

The Variohm range includes, among others, low-pressure transducers, general-purpose stainless steel Pressure Sensors, compact sensors for space-constrained installations, sensors for mobile applications, and Combined Pressure and Temperature Transducers.

A Pressure Sensor for an AI Data Center cooling loop may therefore look very different from one selected for a Radar system, military vehicle, UAV, or Power Electronics cooling circuit.

But the engineering question remains exactly the same:

What information do we need from the coolant to know that the cooling system is still doing its job?

Figure 4: Positioning Pressure Sensors at different points throughout the cooling circuit enables continuous monitoring of system behavior and can help identify changes related to pump performance, flow resistance, leaks, or coolant loss.

Where Should Pressure Be Measured in a Liquid Cooling System?

The location of a Pressure Sensor can be almost as important as the selection of the sensor itself.

A single Pressure Transducer can provide an accurate measurement at one point in the circuit. But when the objective is to understand how the entire liquid cooling system is behaving, pressure measurement at multiple locations can provide much more useful information.

For example, measuring pressure upstream and downstream of the pump allows the control system to monitor pressure conditions on both sides. This type of architecture is commonly used in CDU applications to provide real-time feedback for coolant and thermal management.

The same principle can be applied around other components.

Pressure measurement before and after a Cold Plate can help monitor changes in Pressure Drop across the cooling path.

Measurements around a heat exchanger can help identify changes in hydraulic behavior through that section of the circuit.

And in more complex cooling systems, multiple Pressure Sensors can be strategically positioned to create a Pressure Map of the cooling loop.

The objective is not to fill the system with sensors. It is to select the measurement points where pressure data provides the most useful information about cooling system performance.

A Pressure Sensor Must Match the Coolant – Not Just the Number of Bar

When selecting a Pressure Transducer for a liquid cooling system, pressure range is an obvious place to start.

But it is only the beginning.

The wetted materials must be compatible with the coolant being used. Engineers should also consider media temperature, normal operating pressure, expected pressure peaks, pressure port, sealing, electrical connection, output signal, and environmental conditions.

The measurement range itself should also be selected carefully.

If a cooling circuit normally operates at relatively low pressure, choosing a Pressure Sensor with a Full Scale value far above the actual operating range may not provide the most useful measurement. Ideally, the sensor range should correspond to the region in which the system actually operates while maintaining sufficient margin for expected operating conditions and pressure peaks.

This is where the breadth of the Variohm Pressure Transducer portfolio becomes particularly valuable.

From 0.01 Bar to 5000 Bar – The Right Variohm Pressure Sensor for the Application

Variohm offers a broad portfolio of Pressure Sensors and Pressure Transducers covering very different pressure ranges, installation requirements, and applications.

For systems requiring low-pressure measurement, options include the Variohm EPT8100 and CIT3100, with the CIT3100 designed for particularly low pressure ranges.

For general-purpose applications requiring a robust stainless steel pressure cell and a wide range of configuration options, the Variohm EPT3100 provides a highly flexible platform.

For mobile equipment and demanding environments, families such as the EPT9100 and SMO3100 can be considered depending on the specific system requirements.

And where installation space is limited, Variohm offers compact Pressure Transducers including the EPT1200, EPT1400 and EPT1500.

The point is simple:

There is no single “Pressure Sensor for Liquid Cooling.”

There is a Pressure Sensor that is right for your specific cooling system.

What If the System Needs Both Pressure and Temperature?

This brings us back to the combination at the heart of this article.

Variohm also offers a dedicated range of Combined Pressure and Temperature Transducers, allowing both parameters to be obtained from a single sensor assembly.

The Variohm EPTTE3100, for example, combines pressure measurement up to 25 bar with an external temperature measurement range of -50°C to +150°C.

For even more space-constrained systems, the EPTTE1400 provides a miniature design with a diameter of approximately 14 mm, also with external temperature measurement.

For applications requiring significantly higher pressure ranges, the EPTT5100 offers pressure measurement up to 1000 bar together with internal temperature measurement.

An important distinction should be made here: Internal Temperature and External Temperature are not necessarily the same measurement.

The correct sensor therefore depends on what the engineer actually needs to know about the cooling system.

If the objective is to understand the condition of the coolant itself, both the measurement location and the way temperature is measured become particularly important.

Ultimately, the right question is not:

“Which sensor gives me the most data?”

It is:

“Which Variohm sensor gives me the right data, at the right location, to understand what is happening inside my cooling system?”

Figure 5: Selecting the right Pressure Sensor starts with matching the sensor to the application – from low-pressure liquid cooling circuits to compact and combined Pressure + Temperature Transducers for high-power and defense systems.

Low Pressure Does Not Mean the Measurement Is Less Important

When we talk about Pressure Sensors, it is easy to think first of hydraulic systems operating at hundreds or even thousands of bar.

But in liquid cooling systems, where operating pressures may be relatively low, even a small pressure change can provide valuable information about what is happening inside the cooling circuit.

When a Pressure Transducer is selected with a measurement range that matches the actual operating pressure, the control system can monitor relatively small changes rather than simply detect an extreme overpressure event.

So whether we are looking at a CDU, a Power Electronics cooling loop, or a compact liquid cooling system, the question is not which sensor can measure the highest pressure.

The real question is:

What is the actual operating pressure range, and what changes do we need to detect?

The Variohm Pressure Sensor portfolio includes solutions specifically designed for low-pressure measurement. The CIT3100, for example, offers ranges starting from 0-0.02 bar up to 1 bar, while the EPT8100 covers ranges from 0-0.06 bar up to 10 bar.

Alongside these, broader-range Pressure Transducers such as the Variohm EPT3100 allow engineers to match the sensor to the characteristics of the cooling circuit rather than using a one-size-fits-all solution.

What Happens When the System Gets Smaller?

In a Data Center, there is usually room to accommodate a Pressure Sensor.

Inside a UAV, compact radar system, mission computer, or densely packed Power Electronics unit, the situation can be very different.

Suddenly, sensor diameter, body length, connector type, cable routing, weight and the space required for installation all become part of the engineering specification.

For space-constrained applications, Variohm offers compact Pressure Transducers such as the EPT1200 with a 12 mm diameter, EPT1400 at 14 mm, and EPT1500 at 15 mm.

This can be particularly valuable in defense and aerospace applications, where pressure monitoring may be required even when very little space is available around the cooling lines.

Do Not Select a Pressure Sensor by Pressure Range Alone

Pressure Range is the natural place to start, but it should never be the only selection criterion.

In a real system, engineers also need to consider media temperature, coolant compatibility, wetted materials, pressure port, sealing, electrical output, supply voltage, electrical connection, and environmental conditions.

In mobile systems, shock and vibration may also become important design considerations.

Defense applications may introduce additional environmental and system-level requirements that must be evaluated for the specific project.

And where particularly high media temperatures are involved, a dedicated solution such as the Variohm EPT12R, designed for media temperatures up to 200°C, may be considered.

In other words:

“I need a 10 bar Pressure Sensor” does not define the sensor.

It only starts the conversation.

From a Pressure Sensor to a Smarter Monitoring Point

The next step is to make that measurement point provide even more useful information.

Instead of installing a Pressure Sensor and a separate Temperature Sensor, some applications can use a Combined Pressure and Temperature Transducer.

The Variohm portfolio includes the EPTTE3100, EPTTE1400, EPTT5100 and EPTTE5100, providing combined pressure and temperature measurement in different configurations.

The benefit is not limited to saving installation space.

When both measurements originate from the same installation point, the control system can correlate the hydraulic behavior and thermal behavior of the same area within the cooling circuit.

This brings us back to the central idea of this article:

Temperature tells us how hot the system is. Pressure can help us understand how the cooling circuit is behaving.

Combining the two does not replace a Flow Sensor. It does not diagnose a fault by itself, and it does not automatically turn every cooling system into a Predictive Maintenance system.

But it does give engineers and control systems more information from the same physical measurement point.

And in systems where effective cooling is essential for continued operation, that additional information can be extremely valuable.

When Cooling Becomes Part of the Mission

In an office environment, a cooling failure may be an inconvenience.

In a Data Center, it can result in expensive downtime.

But in a military vehicle, radar system, EW system, UAV, or mission-critical Power Electronics platform, the consequences can be much more significant.

An electronic system may be functioning perfectly from an electrical perspective, but if heat can no longer be removed at the required rate, the system may eventually be forced to reduce performance or shut down.

This means that a small Pressure Sensor installed inside the liquid cooling circuit is not necessarily just another sensor.

It can become one of the sources of information used to determine whether the conditions required for the electronics to continue operating are still being maintained.

As system power increases and electronics become more densely packed, this question becomes increasingly important:

Not only is the system operating now, but can the cooling system continue supporting it through the next minute, the next hour, and the entire mission?

Figure 6: Pressure monitoring at key points in the liquid cooling circuit can help detect changes in system behavior earlier, supporting the identification of pump degradation, blockages, leaks, or unstable flow conditions.

How Do You Select the Right Pressure Sensor for a Liquid Cooling System?

Once we have determined where pressure should be measured and what we want to learn from that measurement, we can select the Pressure Sensor itself.

The first parameter is, of course, Pressure Range.

The sensor must cover both the normal operating pressure and the expected pressure extremes, but a higher range is not necessarily better. If the liquid cooling circuit operates at relatively low pressures, the measurement range should be selected to match the actual operating region while maintaining sufficient safety margin.

Next comes Media Compatibility.

A Pressure Sensor is in direct contact with the coolant, so the sensor’s wetted materials, seals, and mechanical interface must be compatible with the specific fluid used in the system.

Media Temperature is equally important. It is not enough to verify that the ambient temperature is within the sensor’s operating range. Engineers must also check the allowable temperature of the coolant that comes into direct contact with the sensor.

Then come the integration requirements:

Output Signal – for example, 0-10 V, 0.5-4.5 V or 4-20 mA, depending on the Variohm sensor and control system.

Pressure Port – the thread and mechanical connection must match the cooling circuit design.

Electrical Connection – connector or cable, depending on sensor location, installation and maintenance requirements.

Sealing – particularly important where the sensor is exposed to water, dust, moisture or harsh environmental conditions.

Size and Weight – almost insignificant in a large CDU, but potentially critical in a UAV, compact electronic system or military platform.

For mobile applications, expected Shock and Vibration conditions should also be considered.

There Is No Single Pressure Sensor for Every Cooling System

This is perhaps the most important point when selecting a Pressure Transducer.

An AI server cooling loop, radar system, military vehicle and battery system may all use liquid to remove heat, but their sensor requirements can be completely different.

One application may require highly sensitive measurement at very low pressure.

Another may require a robust Stainless Steel design with multiple mechanical and electrical options.

In a third system, installation space may be so limited that sensor diameter becomes a key selection parameter.

And in another application, there may be significant value in obtaining Pressure + Temperature from the same measurement point.

This is why the Variohm Pressure Transducer portfolio includes different sensor families for different engineering requirements – from low-pressure sensors such as the CIT3100 and EPT8100, through the versatile EPT3100, compact solutions such as the EPT1200, EPT1400 and EPT1500, and combined Pressure and Temperature solutions including the EPTTE3100 and EPTTE1400.

The objective is not to select the Pressure Sensor with the most impressive specification.

The objective is to select the Variohm Pressure Sensor that provides the right measurement, in the right range, at the right location, under the actual environmental conditions of the system.

Conclusion – The Cooling System Should Tell Us What Is Happening Inside It

As power density increases, the cooling system is no longer a supporting component. It is becoming a critical part of the overall system architecture.

This is true in AI Data Centers operating thousands of GPUs, and it is equally true in Radar, EW, Power Electronics, battery systems, UAVs and military platforms, where electronics must continue operating under high loads and demanding environmental conditions.

Temperature remains a critical parameter.

But it is not the only one.

Pressure Sensors add valuable information about the behavior of the liquid cooling circuit itself.

Pressure measurements at carefully selected points can help monitor pump behavior, identify changes in Pressure Drop, detect abnormal trends, and provide the control system with additional information before a cooling problem develops into a critical thermal condition.

And where more information is required with fewer components, Variohm Combined Pressure and Temperature Transducers can provide both parameters from a single sensor assembly and measurement point.

Ultimately, an effective liquid cooling system is not simply one that removes heat.

It is a cooling system whose behavior can be measured, monitored, and understood – so we know it continues removing heat exactly as intended.

🧩 Further Reading – Measurement as a System

This article is part of an engineering series exploring how reliable measurement depends on proper system design rather than on a single sensor component.

Before diving deeper into industrial sensing, you may also find the following articles in the series useful:

• VARIOHM Group – When Measurement Is a System, Not a Component
• How to Select Sensors for Harsh Environments: An Engineering Guide for Reliable Measurement in the Real World
• VARIOHM Position Sensors – Engineering Position as a System, Not Just a Signal
• Industrial Pressure Sensors – When Pressure Measurement Becomes a System Engineering Challenge
• Industrial Temperature Sensors – When Temperature Measurement Becomes a System Engineering Challenge
• Choosing the Right Linear Position Sensor: Why Stroke Length Is Only the Beginning
• Contactless Rotary Position Sensors – Why More and More Systems Are Moving to Non-Contact Sensing
• Choosing the Right Temperature Probe Mounting
• How Differential Pressure (ΔP) Can Reveal Problems Long Before a System Shuts Down
• Your Temperature Sensor Says 80°C. The Real Hot Spot Could Already Be at 130°C
• Measuring Pressure Without Temperature Is Only Half the Picture
• Does Your Thermal Protector Really Solve the Problem? Or Just Give the System Another Chance to Fail?
• Why a Linear Position Sensor Shouldn’t Be Selected by Stroke Alone
• Your System Has Powered Up – But Does It Know Where It Is? Absolute Position Sensors vs. Homing
• Your Pressure Sensor May Be Accurate. Your Measurement May Not Be – Why a ±0.5% Accuracy Specification Doesn’t Guarantee a ±0.5% Measurement
• Why Programming a Rotary Position Sensor to 360° Is Sometimes the First Design Mistake
• Why a Dual-Channel Rotary Position Sensor Is Not Just a Backup Sensor
• Your PT100 Sensor Isn’t Reading the Wrong Temperature – Your Wiring Might Be
• Why Every Battery Pack Needs a Temperature Sensor – Not Just Electric Vehicles
• Why a Standard Pressure Sensor Isn’t Always Suitable for Hydrogen Systems

Frequently Asked Questions – FAQ

Why Do You Need a Pressure Sensor in a Liquid Cooling System?

A Pressure Sensor helps monitor the hydraulic behavior of the cooling circuit. Changes in pressure or in the pressure differential between different points can provide an indication of changes in pump performance, flow resistance, blockage, leakage, or coolant loss.

The sensor does not diagnose the fault by itself, but it provides valuable data to the control and monitoring system.

Is Temperature Measurement Alone Enough?

Not always. A Temperature Sensor tells us about the thermal condition of the system, while a Pressure Sensor provides additional information about the behavior of the coolant circuit.

Combining pressure and temperature data can provide a more complete picture of liquid cooling system health and help identify changes in system behavior.

Can a Pressure Sensor Replace a Flow Sensor?

No. Pressure and flow are different physical parameters.

A Pressure Sensor is not a Flow Meter, and a change in pressure alone cannot be used to determine flow rate with certainty. However, pressure measurements at carefully selected locations can provide valuable information about changes in flow resistance and hydraulic conditions within the cooling circuit.

Why Measure Pressure Before and After the Pump?

Measuring pressure on both sides of the pump allows the control system to monitor pressure conditions across it and observe how they change during operation.

In CDU – Coolant Distribution Unit applications, these measurements can form part of the real-time feedback used for liquid cooling system control and monitoring.

What Is Pressure Drop and Why Is It Important?

Pressure Drop is the difference in pressure between two points in a system.

It can be monitored, for example, upstream and downstream of a Cold Plate, filter, heat exchanger, or other cooling component.

A change in Pressure Drop under comparable operating conditions may indicate a change in the hydraulic resistance of that part of the cooling circuit.

What Are the Advantages of a Combined Pressure + Temperature Sensor?

A Combined Pressure and Temperature Transducer provides both measurements from a single sensor assembly and installation point.

This can reduce mechanical connections, wiring, installation space, and component count while providing the control system with two important parameters from the same physical location.

Which Variohm Sensors Combine Pressure and Temperature Measurement?

The Variohm Combined Pressure and Temperature Transducer portfolio includes the EPTTE3100, EPTTE1400, EPTT5100 and EPTTE5100.

These models differ in pressure range, sensor construction, temperature measurement method, mechanical interfaces, and electrical outputs, allowing the sensor to be matched to the specific application.

Which Variohm Pressure Sensor Is Suitable for Low-Pressure Liquid Cooling?

The correct choice depends on the actual operating range and system requirements.

For example, the Variohm CIT3100 offers ranges starting from 0-0.02 bar, while the EPT8100 offers ranges starting from 0-0.06 bar.

Selecting a very high Full Scale pressure range is not necessarily beneficial when the objective is to monitor relatively small pressure changes in a low-pressure cooling circuit.

Are Compact Pressure Sensors Available for Space-Constrained Systems?

Yes. Variohm offers several compact Pressure Transducers, including the EPT1200 with a 12 mm diameter, EPT1400 with a 14 mm diameter, and EPT1500 with a 15 mm diameter.

The EPTTE1400 also provides combined Pressure + Temperature measurement in a compact design of approximately 14 mm diameter.

Can Pressure Sensors Be Used in Defense and Military Cooling Systems?

Pressure monitoring can be relevant to liquid cooling circuits used in Radar, EW, mission computers, Power Electronics, battery systems, military vehicles, UAVs, UGVs, and other unmanned platforms.

Sensor selection for a specific defense application should consider environmental conditions, shock and vibration, temperature, sealing, electrical interface, mechanical integration, and any project-specific qualification or compliance requirements.

What Should Be Considered When Selecting a Pressure Transducer for Liquid Cooling?

Pressure range is only the beginning.

Engineers should also consider Media Compatibility, Media Temperature, Pressure Port, Output Signal, Electrical Connection, Sealing, Size, Weight, and environmental conditions.

For mobile, aerospace, or defense systems, Shock and Vibration and project-specific requirements should also be evaluated.

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Key Terms

Pressure Sensor / Pressure Transducer
A sensor that measures the pressure of a liquid or gas and converts that measurement into an electrical signal for use by a control, monitoring, or protection system.

Liquid Cooling
A cooling method in which liquid is used to transfer heat away from high-power components to a heat exchanger, radiator, or another cooling system.

CDU – Coolant Distribution Unit
A unit responsible for circulating, distributing, and controlling coolant in liquid cooling systems, particularly in Data Center applications.

Cold Plate
A cooling component thermally coupled to a processor, Power Electronics module, or other heat-generating component. Coolant flows through the Cold Plate and absorbs heat from the component.

Pressure Drop
The difference in pressure between two points in a system. Monitoring Pressure Drop can help identify changes in flow resistance across a Cold Plate, filter, heat exchanger, or other component.

Gauge Pressure
Pressure measured relative to atmospheric pressure. It is commonly used in Pressure Transducers for liquid and hydraulic systems.

Absolute Pressure
Pressure measured relative to a perfect vacuum rather than atmospheric pressure.

Pressure Range
The pressure interval over which the sensor is designed to provide measurement. The selected range should match both the normal operating pressure and the expected pressure extremes of the system.

Media Compatibility
The compatibility between the measured fluid and the sensor materials that come into contact with it. This is particularly important in cooling systems using different coolants or fluid mixtures.

Media Temperature
The temperature of the liquid or gas in direct contact with the Pressure Sensor. This should not be confused with the ambient temperature surrounding the sensor.

Combined Pressure and Temperature Transducer
A sensor that integrates pressure and temperature measurement into a single assembly. It can provide both parameters from one installation point while reducing the number of components and connections required.

Internal Temperature Measurement
Temperature measurement from within the sensor assembly. It should not automatically be considered equivalent to direct measurement of coolant temperature.

External Temperature Measurement
Temperature measurement intended to represent external conditions at the measurement point, according to the sensor design and manufacturer’s specification.

Condition Monitoring
Monitoring system parameters and behavior over time to identify changes or deterioration rather than waiting only for a parameter to exceed a predefined limit.

Health Monitoring
The use of sensor data to evaluate the condition of a system or subsystem and identify behavior that may require inspection, maintenance, or further analysis.

Flow Rate
The quantity of fluid passing through the system over a given period of time. A Pressure Sensor is not a Flow Meter, so pressure measurement is not a direct measurement of flow rate.

Output Signal
The electrical signal produced by the sensor, for example 0.5-4.5 V, 0-10 V, or 4-20 mA, depending on the Variohm Pressure Transducer selected.

Pressure Port
The mechanical interface through which the Pressure Sensor is installed in the system and exposed to the pressure being measured.

IP Rating
The Ingress Protection rating of the sensor enclosure against dust and water, such as IP67 or IP68.