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FEMA VCM / VNM Negative Pressure Switches for Liquids and Gases

FEMA VCM / VNM negative pressure switches are used for reliable monitoring of vacuum and negative pressure in systems with non-aggressive liquid and gaseous media. They detect the pressure difference relative to the current atmospheric pressure and switch as soon as the set limit value is reached.

The VCM and VNM series are particularly suitable for applications where a defined vacuum must be monitored, a pump must be controlled or a process must be protected against inadmissible pressure conditions. Typical applications include vacuum systems, pump systems, vessel monitoring, process plants, mechanical engineering, test benches and industrial control and monitoring tasks.

Since the “zero” reference point on the device scale corresponds to the current atmospheric pressure, the specified switching pressure ranges refer to the difference between atmospheric pressure and the set switching pressure. The devices are factory-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 mechanical operating principle makes FEMA VCM / VNM negative pressure switches robust, durable and easy to integrate into existing systems. No additional auxiliary power is required for pressure detection itself. The applied negative pressure acts on a mechanical measuring element, which actuates a microswitch and provides an electrical switching signal.

Typical Applications

• Monitoring of vacuum and negative pressure in industrial systems
• Control and protection of vacuum pumps
• Pressure monitoring in vessels, pipelines and process systems
• Monitoring of non-aggressive liquid and gaseous media
• Mechanical engineering, plant engineering and process technology
• Test benches, laboratory systems and technical supply systems
• Limit monitoring at falling pressure

Advantages of FEMA VCM / VNM Negative Pressure Switches

• Suitable for liquids and gases: designed for non-aggressive liquid and gaseous media
• Reliable vacuum monitoring: switching when the set negative pressure value is reached
• Mechanical switching principle: no auxiliary power required for pressure detection
• Robust design: suitable for industrial environments and long service life
• Easy adjustment: switching point can be set directly on the device
• Clear reference scale: scale refers to the pressure difference relative to atmospheric pressure
• Proven FEMA technology: suitable for monitoring, control and protection functions

VCM / VNM Negative Pressure Switches at ICS Schneider

ICS Schneider offers FEMA VCM / VNM negative pressure switches for various industrial pressure and vacuum monitoring applications. The devices are suitable for monitoring non-aggressive media and can be used for limit monitoring, pump control or process protection depending on the application requirements.

When selecting the right negative pressure switch, the medium, switching range, required switching point, temperature, process connection, electrical switching capacity, ambient conditions and installation situation should be considered. For special applications, high operational safety requirements or specific media, ICS Schneider can support the technical selection.

FAQ – Frequently Asked Questions about FEMA VCM / VNM Negative Pressure Switches

1. What is a FEMA VCM / VNM negative pressure switch?

A FEMA VCM / VNM negative pressure switch is a mechanical switch used to monitor vacuum or negative pressure. It switches as soon as the set negative pressure value is reached.

2. Which media are VCM / VNM negative pressure switches suitable for?

The devices are designed for non-aggressive liquid and gaseous media. For aggressive, contaminated or particularly hot media, suitability must be checked based on the technical data.

3. What does negative pressure mean in this context?

Negative pressure means that the pressure in the system is lower than the surrounding atmospheric pressure. The negative pressure switch measures the difference between atmospheric pressure and the pressure present in the system.

4. What does the zero point on the scale refer to?

The zero point on the device scale corresponds to the current atmospheric pressure. The displayed values therefore refer to the pressure difference between atmospheric pressure and the set switching pressure.

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

The VCM and VNM series are factory-calibrated for falling pressure. This means that the value set on the scale corresponds to the switching point when the pressure decreases.

6. Does the VCM / VNM negative pressure switch require a supply voltage?

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

7. Where are VCM / VNM negative pressure switches used?

Typical applications include vacuum systems, pump systems, vessels, pipelines, test benches, mechanical engineering and industrial process plants.

8. Can the devices be used for pump control?

Yes, negative pressure switches can be used to control or monitor vacuum pumps, for example to ensure a minimum vacuum or to switch a pump when a defined limit value is reached.

9. What information is important for selecting the right device?

Important information includes the medium, switching range, desired switching point, maximum pressure load, temperature, process connection, electrical connection, switching capacity and ambient conditions.

10. Are VCM / VNM negative pressure switches suitable for safety-related applications?

They can be used for monitoring and protection functions. Whether they are suitable for a specific safety-related application must be checked based on the technical requirements, approvals and operating conditions.