Non-Electrical Explosion Protection – Looking Beyond the Obvious

Explosion protection is often strongly associated with electrical and electronic systems: cables, motors, control units. But protecting against explosions goes far beyond that. Even purely mechanical equipment can pose a hazard. Therefore, it is important to consider explosion protection holistically – taking both electrical and non-electrical aspects into account.

For example, operating a mixer, pump, or pneumatic drive in an explosive atmosphere presents particular challenges. The fundamental principle is: a potential ignition source must not become effective.

Several factors play a role, such as:

• Sizing and design: Material failure due to overload or wear can cause friction or sparks.
• Grounding: To prevent electrostatic charges.
• Maintenance and malfunctions: Missing lubricant or insufficient cooling fluid can cause overheating.

This demonstrates: even if no electricity is flowing, equipment can still trigger an explosion.

In non-electrical explosion protection, ignition hazard assessment is the central instrument. The key question is: how does a potential ignition source become an effective one – and how can we prevent it?

The non-electrical protection methods should be applied in a defined sequence:

1. Constructive safety (design-based protection): Devices and assemblies should be designed and made of materials in such a way that no dangerous ignition sources, such as hot surfaces or mechanically generated sparks, can occur. Using this type of protection often eliminates the need for additional space or safety-critical components.
2. Ignition source monitoring: Critical parameters such as temperature, pressure, speed, or lubricant levels are monitored. If a safety-relevant limit is exceeded, protective measures are triggered.
3. Enclosures and barriers (liquid encapsulation, pressurized encapsulation, protective housings): If risks cannot be controlled by design or monitoring, contact between ignition sources and the explosive atmosphere must be avoided.
4. Flameproof or pressure-resistant encapsulation – controlled explosion: As a last option, devices and assemblies must be designed to withstand an internal explosion and safely vent it externally.

Due to current trends, ignition source monitoring is becoming increasingly interesting. Sensors can detect the condition of machines, equipment, assemblies, or components. Examples include:

• An oil pressure switch signaling missing lubrication.
• Speed monitoring to detect unusual vibrations.
• Temperature sensors detecting overheating.

Important considerations:

• Monitor only what is truly critical for explosion protection. This requires knowledge of the parameters and their critical limits.
• Sensors and evaluation units must be approved for use in explosive atmospheres.
• Systems must be fail-safe and respond safely even in the event of failure.

Modern technologies offer great potential here: Industry 4.0, digitalization, and artificial intelligence. If machines are already equipped with sensors and data transmission, this data can also be used to detect hazardous conditions early – before an ignition source develops.

Example: Dry running is a common hazard for pumps in explosive atmospheres. Traditionally, it is monitored with separate sensors – adding effort and maintenance. Newer approaches, however, use the motor’s existing performance data to detect dry running. This saves space, reduces costs, and minimizes potential points of failure.

For explosion protection, both manufacturers and operators have their own duties:

• Manufacturers must eliminate ignition hazards during development and clearly define protective measures in the operating manual.
• Operators must use equipment as intended and ensure through maintenance and monitoring that the protection measures are effective.

Defining the right monitoring parameters is particularly important. Only when it is clear which values are critical – such as temperature, speed, or lubrication – can suitable sensors be selected and limits set.

The topic of “ignition source monitoring” is at the beginning of an exciting development. With more data, smarter sensors, and methods from functional safety, new opportunities could emerge to make non-electrical explosion protection more efficient and reliable.

Looking beyond the scope of electrical explosion protection is worthwhile – for manufacturers, operators, and above all, for safety.