Ex Automation Ex p System R. STAHL

Protecting your equipment in hazardous locations

Modular enclosure pressurisation with the R. STAHL Ex p System

Working in an environment with gas mixtures or fine particles? Then you need a suitable protection concept to avoid ignition hazards. One solution can be the pressurised enclosure Ex p, which is particularly suitable for the protection of electrical units with high space and energy requirements.

The Problem: Systems from other manufactures use a large number of dedicated devices for different control panel sizes and designs.

The Solution: The new generation of control and monitoring systems from our explosion protection specialists. This is a protection pressurised enclosure and filters all the traditional complexities to only three basic components. The novel Ex p system guarantees the flexible assembly of Ex p control panels at any time and opens up far reaching possibilities for integrating industrial control of all kinds in explosion protection areas.

In our unique system, Ex p controller, Ex p pressure monitors and Ex p purge valves (with digital and proportional control) ensures that the modular system meets all requirements from very small (10 litres volumes) to very large (4,000 litres). The Ex p system can be used in gas explosion hazard Zone 1 and Zone 2 areas, as well as dust explosion hazard areas zone 21 and 22.

Ex Automation Ex p Controler R. STAHL

This controler provides all the control processes,

no matter the cabinet size, and is adaptable

to different requirements.

Ex Automation Ex p Pressure Monitor R. STAHL

Precise pressure control within Ex p pressure

monitor enables a cost-effective operation

allowing for switch off of operation close to

switch-off thresholds. At the same time, these

monitors reduce leakage amounts to the minimum.

Ex Automation Ex p Purge Valves R. STAHL

These transport protective gases or compressed air

to the interior of the Ex p enclosure on the basis of

time intervals and/or pressure values.


Reduced handling
With the core components having extremely small dimensions, it’s not just the externally installed Ex p system that allows you to save space. The reduced size not only gives you more room for technology, but also allows for ultimate flexibility in dealing with different control cabinet volumes. Even when larger cabinets require an increase in the number of outlets, this is no problem. Further Ex p pressure monitors can be quickly installed.

Reduced operating costs
With improved flow technology, the supply needs of compressed air have been drastically reduced without compromising at all on high system availability. That saves energy costs.

Inspection and maintenance are also simplified. Using an Ex p bypass key switch, the electronics work in an intrinsically safe mode, reducing the amount of time needed for maintenance measures. Not only are cost and time intensive construction and testing steps unnecessary, but also explosion protection is retainedwithout lengthy procedures. 



The Ex p controller allows for uncomplicated and demand-oriented flow conditions. This is independent of the control panel size. For example, compressed air or inert gas is fed into the control cabinet via the Ex p purge valve and discharged to the outside via positioned Ex p pressure monitors. The result is a guarantee of very short purge times with very low-pressure loads. An upside of this is that switch cabinet wall thicknesses can be less than 2mm, creating reduced manufacturing costs. Temperature monitoring and control is of course also integrated to ensure adequate cooling.

R. STAHL’s Ex p system is certified as a monitoring system for control panels. This is used in Zone 1 as a redundant failsafe and in Zone 2 as a cost-reduced single version (according to IEC / EN 60079-2). The design of the components, paired with the Ex p control unit’s modern user interface, allows for each commissioning and maximum user-friendliness.

The division in favour of only one version of the Ex p pressure switch, or in the case of large control cabinets, simply increasing the number, reduces the effort for engineering and warehousing.


R. STAHL is the leading international provider of explosion protection components and systems. When you choose us for a protection pressurised enclosure, such as the Ex p system, you can know that you will get trustworthy advice, high quality engineering and professional commissioning of any tailor made solutions you may need to fully meet your requirements. We are proud to be able to look back on our numerous, standard setting Ex p systems.

Ex Automation Ex p Systems R. STAHL


Customised Ex p systems, in the
middle of a desert: Our contribution
to the long-term success of a
gasworks in Saudi Arabia.



Which type of protection do you need? System operators can decide when choosing the type of protection. Even when the dimensions, functional design or cooling requirements of the application limit the alternatives.

The main advantage of protection pressurised enclosures such as Ex p? Compressed air or pressurised inert gases prevent explosive atmosphere from encountering the insides of the control cabinet. With this security of a non-explosive atmosphere in the installation space, you can install standard industrial technology throughout and are not thus dependent on the use of specially protected assemblies. This saves space for other devices important to the smooth running of your processes. At the same time, you do not need to be considered with limitations in energy requirements or economical uses of space for cooling devices. The other advantage is a problem free installation of larger windows to allow a clear view of any device displays within the cabinet.

But how does the Ex p pressurised enclosure work? The operation takes place in three simple steps.

  1. Preparation: Compressed air or inert gases are feed into the Ex p enclosure via the purge valve. This creates an overpressure. Once this is reached, the purging phase begins, completely regulated by the control unit.
  2. Pre-purging: Before commissioning the equipment located inside the control cabinet, a potentially explosive mixture must be removed from the housing. After the set internal pressure is reached, the air outlet valve opens. From this point, protective gas then purges the inside of the cabinet. The air outlet valve then closes, and this purge flow stops. The internal pressure of the enclosure adjusts itself to the pre-set value and the outlet closes.
  3. Operating Phase: Normal operations now begin, and the control unit starts regulating the internal pressure of the enclosure to prevent the ingress of explosive gasses or ducts. Leakage losses are also compensated for by the Ex p pressure switches.

Do you want to know more of the function, methods and advantages of protection pressurised enclosures like Ex p? Then visit our blog.