---

Ex-DCM / Ex-DNM Pressure Switches for Liquids and Gases

FEMA Ex-DCM / Ex-DNM pressure switches are used for overpressure monitoring in potentially explosive atmospheres. They are suitable for industrial applications with non-aggressive liquids and gases where a defined pressure limit must be detected reliably and transmitted as an electrical switching signal.

The Ex-DCM and Ex-DNM series are designed as universal pressure switches for Ex applications. They combine proven mechanical FEMA pressure switch technology with an explosion-protected design for system areas where flammable gases, vapours or dusts may occur. Typical applications include mechanical engineering, plant engineering, pneumatics, hydraulics, process plants, compressed air systems and industrial media circuits.

The devices are calibrated for falling pressure. This means that the switching pressure set on the scale corresponds to the switching point when the pressure is falling. The reset point is higher by the amount of the switching differential. The switching differential is not adjustable and is defined by the respective device version.

Depending on the version, different setting ranges are available – from very low mbar ranges up to higher pressure ranges in the bar range. The Ex-DCM / Ex-DNM series is designed according to ATEX 2014/34/EU. SIL2 according to IEC 61508-2 and IECEx are also specified in the product information. Electrical integration must be carried out according to the requirements of the respective Ex zone and system classification.

Pressure detection is mechanical. The applied pressure acts on a measuring element which actuates a microswitch when the set switching point is reached. The switching signal can be used for control, shutdown, alarm or lockout functions within a system control.

Typical Applications

• Overpressure monitoring in potentially explosive atmospheres
• Pressure monitoring for non-aggressive liquids and gases
• Applications in mechanical engineering and plant engineering
• Pressure monitoring in pneumatic and hydraulic systems
• Limit monitoring in process plants and media circuits
• Monitoring of compressed air, neutral gases and suitable liquids
• Switching, alarm and shutdown functions in Ex applications

Advantages of FEMA Ex-DCM / Ex-DNM Pressure Switches

• For hazardous areas: designed for potentially explosive atmospheres according to ATEX 2014/34/EU
• Universal use: suitable for non-aggressive liquids and gases
• For overpressure monitoring: reliable switching when the set pressure value is reached
• Calibrated for falling pressure: the set scale value corresponds to the switching point when pressure decreases
• Mechanical switching principle: no auxiliary power required for pressure detection
• Robust industrial design: suitable for mechanical engineering, pneumatics, hydraulics and process plants
• Certified design: depending on the version, with ATEX, IECEx and SIL2 according to IEC 61508-2

Ex-DCM / Ex-DNM Pressure Switches at ICS Schneider

ICS Schneider offers FEMA Ex-DCM / Ex-DNM pressure switches for industrial pressure monitoring tasks in potentially explosive atmospheres. The devices are suitable for operators, plant manufacturers and service companies that require a robust mechanical solution for overpressure monitoring in Ex applications.

When selecting the correct Ex-DCM or Ex-DNM pressure switch, the medium, pressure range, required switching point, maximum permissible pressure, temperature, process connection, electrical switching capacity, Ex zone, type of protection, protection rating, installation situation and safety function should be considered. For Ex applications, the design should always be based on the specific system classification and applicable explosion protection requirements.

FAQ – Frequently Asked Questions about FEMA Ex-DCM / Ex-DNM Pressure Switches

1. What are FEMA Ex-DCM / Ex-DNM pressure switches?

FEMA Ex-DCM / Ex-DNM are mechanical pressure switches used for overpressure monitoring in potentially explosive atmospheres. They switch when a set pressure limit is reached.

2. Which media are Ex-DCM / Ex-DNM suitable for?

The devices are intended for non-aggressive liquids and gases. Exact suitability depends on the medium, temperature, pressure range, materials and operating conditions.

3. What does Ex version mean?

Ex version means that the pressure switch is intended for use in potentially explosive atmospheres. Exact suitability must match the Ex zone, type of protection and system classification.

4. What does ATEX 2014/34/EU mean?

ATEX 2014/34/EU is the European directive for equipment and protective systems intended for use in potentially explosive atmospheres. Ex-DCM / Ex-DNM are designed for corresponding applications.

5. What does “calibrated for falling pressure” mean?

This means that the switching pressure set on the scale corresponds to the switching point when the pressure is falling. The reset point is higher by the amount of the switching differential.

6. Is the switching differential adjustable?

No. The switching differential of Ex-DCM / Ex-DNM is not adjustable. It is fixed depending on the respective device type and pressure range.

7. What applications are Ex-DCM / Ex-DNM used for?

Typical applications include pressure monitoring in process plants, mechanical engineering, pneumatics, hydraulics, compressed air systems and media circuits in potentially explosive atmospheres.

8. Do Ex-DCM / Ex-DNM require a supply voltage?

No supply voltage is required for mechanical pressure detection itself. An electrical connection is only required for the switching contact or switching signal.

9. Which certifications are specified?

The product information specifies, among others, SIL2 according to IEC 61508-2, IBExU12ATEX1040 according to ATEX 2014/34/EU and IECEx IBE 14.0077.

10. How do Ex-DCM / Ex-DNM differ from standard DCM / DNM pressure switches?

Ex-DCM / Ex-DNM are designed for potentially explosive atmospheres. Standard DCM / DNM pressure switches are intended for standard applications without corresponding Ex requirements.

11. Can Ex-DCM / Ex-DNM be used in hydraulics and pneumatics?

Yes. With suitable media and matching pressure ranges, Ex-DCM / Ex-DNM can be used in pneumatic and hydraulic applications. Media compatibility and Ex requirements must be checked.

12. What information is important for selecting the correct version?

Important information includes the medium, pressure range, switching point, maximum operating pressure, temperature, process connection, electrical switching capacity, Ex zone, type of protection, protection rating, installation situation and required switching function.