Yes, in many cases secondary protection is mandatory alongside an overpressure relief device. Dutch and European safety standards require redundant safety systems for critical industrial applications to prevent single point of failure risks. The necessity depends on the pressure class, application area and potential consequences of system failure.
What is secondary protection and when is it mandatory alongside an overpressure relief device?
Secondary protection is a backup safety system that activates when the primary overpressure relief device fails. It forms a second line of defence against dangerous pressure buildup in industrial systems.
According to the Dutch Working Conditions Act and the European Pressure Equipment Directive (PED), secondary protection is mandatory for:
- pressure equipment in categories III and IV (high pressure/volume combinations)
- systems with toxic or flammable media
- installations where failure could lead to serious injury
- critical processes where interruption causes major economic damage
The requirement applies specifically when a risk analysis demonstrates that single protection provides insufficient safety. This is particularly relevant for nitrogen and compressed air installations in data centres, laboratories and industrial processes where high reliability is essential.
What risks arise if you rely solely on one overpressure relief device?
Dependence on one overpressure relief device creates single point of failure risks that can have catastrophic consequences. Primary overpressure relief devices can fail due to mechanical defects, contamination, corrosion or incorrect calibration.
Possible failure scenarios include:
- spring-loaded valve sticking due to contamination or crystal formation
- material fatigue after prolonged exposure to pressure fluctuations
- corrosion of valve components by aggressive media
- incorrect setting after maintenance or replacement
- mechanical damage during transport or installation
Upon failure, pressure can rise above the system’s design pressure, which may lead to pipe rupture, explosions or toxic leaks. In critical applications, such as hospitals or data centres, the consequences can be far-reaching for business continuity and safety.
How do you choose the right type of secondary protection for your system?
The choice of secondary protection options depends on the medium, pressure class, required response time and operating conditions. Each option has specific advantages and disadvantages for different applications.
Available secondary protection options:
- Backup overpressure relief devices: a second safety valve connected in parallel, ideal for continuous processes
- Rupture discs: single-use protection with guaranteed activation, suitable for emergency situations
- Electronic pressure monitoring: sensors with automatic shutdown, ideal for automated systems
- Combination systems: mechanical and electronic protection combined for maximum redundancy
For nitrogen installations in data centres, electronic systems are often preferable due to their rapid response. For compressed air compressors in production environments, mechanical backup valves offer greater robustness against contamination and vibrations. For explosive atmospheres, ATEX vacuum overpressure relief devices are essential.
What should you consider when installing secondary protection systems?
Correct installation of redundant safety systems requires careful planning of positioning, independence and testability. Improper installation can undermine the effectiveness of both protection levels.
Important installation aspects:
- independent piping to both protection systems
- different settings: secondary protection 5–10% higher than primary
- accessibility for periodic inspection and maintenance
- sufficient discharge capacity for both systems combined
- separation of electronic and mechanical systems to prevent common mode failures
Certification by an approved inspection body is mandatory for pressure systems falling under PED regulations. Documentation must demonstrate that both protection levels function independently and meet the specified safety requirements.
How Presscon helps with secondary protection systems
We design and install redundant safety systems for nitrogen and compressed air installations that fully comply with Dutch and European safety standards. With our 25 years of experience, we can determine the right protection configuration for any specific application.
Our services include:
- risk analysis and determination of required protection levels
- selection of optimal secondary protection solutions per application
- professional installation with correct positioning and calibration
- certification and documentation for inspection bodies
- periodic maintenance and testing of both protection levels
Do you have questions about secondary protection for your pressure system? Please contact us for a no-obligation risk analysis and advice on the right protection configuration for your specific situation.
Frequently Asked Questions
How often should I test and maintain my secondary protection system?
Secondary protection systems must be tested at least annually in accordance with NEN-EN-ISO 4126 standards. For critical applications we recommend six-monthly checks. Electronic systems require monthly function tests, whilst mechanical backup valves must be dismantled and inspected annually for wear and contamination.
What does implementing secondary protection cost and how does this relate to the risks?
Costs vary from €500-2000 for simple mechanical backups to €5000-15000 for advanced electronic systems. This investment is minimal compared to potential damage: pipe rupture can cost €50000-500000, excluding business interruption. A risk analysis usually shows a payback period of less than one year.
Can I upgrade existing systems with secondary protection or does everything need replacing?
Most existing systems can be upgraded without complete replacement. We often add electronic pressure monitoring to existing mechanical systems, or install parallel backup valves. The piping configuration usually determines upgrade possibilities - in 80% of cases adaptation is possible without major system changes.
How do I know if my current overpressure relief device still functions reliably?
Check the activation pressure annually with a calibrated test setup, inspect for corrosion or contamination around the valve, and listen for unusual sounds during operation. Replacement is needed for deviations >5% from the set pressure, visible damage or if the valve does not close completely after activation. Document all test results for inspection bodies.
What insurance benefits does secondary protection offer?
Many business insurers offer 10-25% premium discounts for systems with redundant protection, because the damage risk decreases significantly. Additionally, adequate protection can prevent claims that might otherwise not be covered due to 'insufficient precautionary measures'. Some insurers even require secondary protection for high-risk installations.
What happens during an inspection if I don't have secondary protection whilst this is mandatory?
An inspection body can refuse or withdraw the certificate, meaning you may no longer use the system until compliance is achieved. This results in immediate business interruption and possible fines up to €83000. Additionally, you become personally liable for any damage resulting from system failure, which is not covered by insurance.