In many industrial systems, pressures must not only be measured, but also safely monitored or limited. In this context, the general term pressure switch is often used. From a technical point of view, however, it is important to distinguish whether a simple pressure switch, a pressure monitor or a pressure limiter is required.
This distinction is particularly important in safety-related applications. These include, for example, hot water systems, steam systems, burner technology, fuel gases, liquid fuels or pressure vessels. If an unsuitable device is used here, the system may not operate reliably or may not meet the required safety function.
This article explains the difference between a pressure monitor and a pressure limiter, shows typical areas of application and provides practical guidance for correct selection.
You can find an overview of suitable devices in our category
FEMA pressure switches.
Table of contents
- Why is the distinction important?
- What is a pressure monitor?
- What is a pressure limiter?
- Pressure switch, pressure monitor and pressure limiter compared
- Automatic reset or manual release?
- Typical applications: steam, hot water, gas and burner technology
- When is a standard pressure switch not sufficient?
- Selection criteria for safety-related pressure monitoring
- Practical examples from industrial systems
- Checklist for technical clarification
- Conclusion
- FAQ: frequently asked questions about pressure monitors and pressure limiters
Why is the distinction important?
A pressure switch may be sufficient in simple applications to trigger a switching operation. For safety-related tasks, however, a defined monitoring or limiting function is often required. In this case, it must be checked whether a pressure monitor or pressure limiter is needed.
The difference is not just in the name. The decisive factors are function, reset behavior, approval, switching behavior and the specific task within the system.
- Pressure switch: switches at a set pressure value.
- Pressure monitor: monitors a limit value and switches when it is exceeded or undershot.
- Pressure limiter: limits a safety-related pressure condition and often requires deliberate reset.
- Safety function: must be considered separately depending on the application, standard and system concept.
For applications with special requirements, there are specific categories such as
pressure monitors and pressure limiters.
What is a pressure monitor?
A pressure monitor monitors a set pressure limit value. If this limit value is reached, exceeded or undershot, the electrical contact switches. The pressure monitor is therefore used to monitor a defined operating condition.
Depending on the application, a pressure monitor can, for example, switch off a pump, enable a burner, trigger a warning signal or inform a control system.
Typical features of a pressure monitor
- Monitoring of an adjustable pressure value
- Switching contact for control or safety circuits
- Use for overpressure, vacuum or differential pressure
- Automatic reset possible depending on version and application
- Use in industrial systems, heating systems, burner technology or process plants
For applications with hot water, steam, gas and liquid fuels, for example, the
DWR pressure monitor
may be relevant.
What is a pressure limiter?
A pressure limiter is used when a pressure value is not only to be monitored, but safely limited. It has a stronger safety-related function than a simple pressure switch. In many applications, deliberate reset is required after the limit value has been reached.
This means: if the pressure limiter has tripped, the system must not automatically continue operating as soon as the pressure drops again. Instead, the cause must be checked and the reset must be carried out deliberately.
Typical features of a pressure limiter
- Limitation of a safety-related pressure condition
- Switching when a critical limit value is reached
- Often with manual reset or locking function
- Use with steam, hot water, fuel gases or pressure systems
- Use when automatic restart is not permitted or not desired
In potentially explosive atmospheres, special versions such as
Ex-DWR pressure monitors and pressure limiters
may be required.
Pressure switch, pressure monitor and pressure limiter compared
The following table shows the most important differences in simplified form. The specific selection must always be made based on the application and the technical requirements.
| Device type | Main function | Typical application | Reset |
|---|---|---|---|
| Pressure switch | Switching at a set pressure value | Pump control, compressor, mechanical engineering | usually automatic via pressure change |
| Pressure monitor | Monitoring of a pressure limit value | Burner, heating system, compressed air, hydraulics | automatic or manual depending on version |
| Pressure limiter | Safety-related limitation of a pressure value | Steam, hot water, fuel gas, liquid fuel | manual reset often required |
| Differential pressure monitor | Monitoring of the pressure difference between two measuring points | Filter, pump protection, flow monitoring | depending on application and device |
Automatic reset or manual release?
A particularly important difference lies in the reset behavior. For simple monitoring tasks, the contact may often switch back automatically as soon as the pressure is back within the permissible range. For safety-related functions, however, this may be undesirable or impermissible.
A manual reset ensures that the system does not restart uncontrollably after a limit value has been exceeded. This forces the operator to check the cause of the shutdown.
| Reset type | Description | Typical use |
|---|---|---|
| Automatic reset | The contact switches back as soon as the pressure falls below or rises above the reset point again. | Operating monitoring, control tasks, non-safety-critical applications |
| Manual reset | After tripping, the device or system must be deliberately released. | Safety shutdown, pressure limitation, critical system conditions |
| Electrical interlock | The reset is performed via the control system or a safety circuit. | Systems with higher-level safety control |
Why manual reset can be important
- The cause of the pressure exceedance must be checked.
- Automatic restart should be prevented.
- The system should only continue operating after release by operating personnel.
- Safety functions must be triggered in a traceable manner.
- Fault conditions should not be hidden by short-term pressure normalization.
Typical applications: steam, hot water, gas and burner technology
Pressure monitors and pressure limiters are used particularly where an incorrect pressure condition can have dangerous consequences. These include thermal systems, burner technology, pressure vessels, gas supply and systems with hot or energy-rich media.
| Application | Typical task | What to consider |
|---|---|---|
| Steam systems | Monitoring or limitation of steam pressure | Temperature, pressure range, siphon, approval |
| Hot water systems | Protection against impermissible overpressure | Medium temperature, safety function, reset |
| Fuel gases | Monitoring of minimum or maximum pressure | Gas approval, switching function, installation situation |
| Liquid fuels | Pressure monitoring in supply or burner systems | Medium compatibility, temperature, seals |
| Pressure vessels | Limit value monitoring or safety shutdown | Maximum pressure, directives, system concept |
For such applications, it should be specifically checked whether a device from the
pressure monitors and pressure limiters
range is required.
When is a standard pressure switch not sufficient?
A standard pressure switch is often sufficient if only an operating condition is to be switched or signaled. However, as soon as the pressure value takes on a protective function, the application must be considered more closely.
A standard pressure switch should be critically checked if:
- a safety-related shutdown is required,
- steam, hot water, fuel gas or liquid fuels are monitored,
- manual reset is required,
- approval or testing according to certain directives is necessary,
- the system must not restart automatically after tripping,
- exceeding a limit value can lead to dangerous operating conditions,
- the pressure switch is part of a safety circuit.
For simple industrial applications without special safety requirements, universal pressure switches such as the
DCM3 universal pressure switch
may be suitable. For safety-related applications, however, a suitable pressure monitor or pressure limiter should be checked.
Selection criteria for safety-related pressure monitoring
For safety-related pressure monitoring, specifying a switching point alone is not sufficient. The application must be considered as a whole. Only then can it be decided whether a pressure monitor, pressure limiter or special Ex version is required.
| Criterion | Why it is important | Example |
|---|---|---|
| Function | Determines whether switching, monitoring or limiting is required. | Pressure switch, pressure monitor or pressure limiter |
| Switching point | The limit value must be safely within the setting range. | Shutdown at 10 bar rising pressure |
| Reset | Automatic or manual reset influences the safety function. | Manual release after limit value exceedance |
| Medium | Materials, seals and temperature limits must be suitable. | Steam, hot water, fuel gas, oil |
| Temperature | Hot media may require additional measures. | Siphon for steam applications |
| Approval | Certain applications require tested or approved devices. | ATEX, DVGW, TÜV, SIL depending on application |
| Electrical contact | The contact must match the control system or safety circuit. | Normally closed, normally open, changeover contact |
| Installation location | The pressure must be monitored at a suitable point. | Stable measuring point, no strong pulsations |
Practical examples from industrial systems
Example 1: Overpressure monitoring in a hot water system
In a hot water system, an impermissible pressure increase must be detected. A simple pressure switch may be unsuitable here if a safety-related shutdown with defined reset is required. In such cases, a suitable pressure monitor or pressure limiter should be checked.
Example 2: Fuel gas monitoring on a burner
In a burner, both excessively low and excessively high gas pressure can be problematic. The pressure monitor must match the gas type, pressure range, switching function and required approvals. It is also important whether the switching function is part of a safety circuit.
Example 3: Steam application with high medium temperature
With steam, not only the pressure range must be correct. The medium temperature and installation are also decisive. Additional measures such as a suitable cooling section or siphon are often required to ensure that the switching device is not exposed to impermissible thermal loads.
Example 4: Hazardous area with safety-related pressure monitoring
If pressure monitoring takes place in a potentially explosive atmosphere, Ex zone, gas or dust group, temperature class and type of protection must also be checked. Special versions such as
Ex-DWR pressure monitors and pressure limiters
may be suitable for this purpose.
Checklist for technical clarification
For the selection of a pressure monitor or pressure limiter, all technical information should be available wherever possible. Complete clarification is particularly important for safety-related applications.
| Information | Example | Why important? |
|---|---|---|
| Device function | Pressure monitor or pressure limiter | Basis for correct selection |
| Switching point | Shutdown at 8 bar rising pressure | Determines the required setting range |
| Reset behavior | automatic or manual | Important for safety function and restart |
| Operating pressure | Normal operation 5 to 6 bar | Check distance to switching point |
| Maximum pressure | Short-term up to 12 bar | Protection against device overload |
| Medium | Steam, hot water, natural gas, oil | Check materials, seals and approvals |
| Medium temperature | For example 120 °C or 180 °C | Check thermal load and installation |
| Environment | Indoor area, outdoor area, Ex zone | Check ingress protection, Ex protection and housing version |
| Electrical connection | Terminal connection, plug, cable gland | Compatibility with system and control |
| Contact function | Normally closed, normally open or changeover contact | Integration into control system or safety circuit |
| Required approval | ATEX, DVGW, TÜV, SIL | Depending on system and application area |
Conclusion: the device function must match the safety task
Whether a pressure switch, pressure monitor or pressure limiter is required does not depend only on the pressure range. The decisive factor is the task within the system. If only an operating condition is to be signaled, a simple pressure switch may be sufficient. However, when monitoring or limiting a safety-related pressure condition, pressure monitors or pressure limiters must be specifically checked.
Especially with steam, hot water, fuel gases, liquid fuels, pressure vessels or hazardous areas, switching function, reset, approval, medium and temperature should be carefully clarified.
You can find a suitable preselection in the categories
FEMA pressure switches
and
pressure monitors and pressure limiters.
FAQ: frequently asked questions about pressure monitors and pressure limiters
What is the difference between a pressure monitor and a pressure limiter?
A pressure monitor monitors a pressure limit value and switches when this value is reached. A pressure limiter is used when a safety-related pressure condition needs to be limited. Depending on the application, pressure limiters often have a manual reset or locking function.
When is a standard pressure switch sufficient?
A standard pressure switch may be sufficient if only an operating condition is to be switched or signaled. For safety-related applications, steam, hot water, fuel gas or liquid fuels, it should be checked whether a pressure monitor or pressure limiter is required.
Why is manual reset important?
Manual reset prevents a system from restarting automatically after a limit value has been exceeded. This means that the cause of the shutdown must be checked before the system is released again.
Which FEMA pressure monitor is suitable for hot water, steam, gas or liquid fuels?
For such applications, the
DWR pressure monitor
may be a suitable series. However, the exact version must be selected based on pressure range, medium, temperature, connection, switching function and approval.
Can a standard pressure switch be used for steam?
Not automatically. Steam applications place special demands on temperature, installation and safety function. Additional measures such as a siphon or suitable cooling section often need to be considered. A special pressure monitor or pressure limiter may also be required.
What is important in fuel gas applications?
In fuel gas applications, pressure range, gas type, switching function, approval and integration into the burner control system must be checked. Depending on the system, a special pressure monitor with suitable approval may be required.
Are there pressure monitors and pressure limiters for hazardous areas?
Yes, special Ex versions are available for potentially explosive atmospheres. Here, zone, gas or dust group, temperature class and type of protection must match the application. One example is
Ex-DWR pressure monitors and pressure limiters.
What does the Pressure Equipment Directive have to do with pressure monitors?
For certain pressure systems, requirements from the Pressure Equipment Directive or system-specific regulations may be relevant. Whether a suitably tested pressure monitor or pressure limiter is required must be checked based on the specific system.
What information is required for selection?
Important information includes device function, switching point, reset behavior, operating pressure, maximum pressure, medium, temperature, pressure connection, electrical connection type, contact function, installation environment and required approvals.
Where can I find suitable FEMA pressure monitors and pressure limiters?
You can find an overview in the category
pressure monitors and pressure limiters
as well as in the main category
FEMA pressure switches.