How can you check whether a machine is safe?

How to check whether a machine is safe: From the perspective of an engineer and a business owner who builds or modernises machinery, it is important not only to select and design all safeguarding solutions correctly, but also to verify that these safeguards actually work in practice. The article below explains, step by step, how to check whether the implemented preventive and risk-reduction measures are effective, which standards and best practices are worth applying, and how to take care of the formal documentation side (e.g., the EU declaration of conformity) and compliance with regulations (including the Machinery Directive). This guide will show you what to pay particular attention to and which mistakes to avoid, so you can be confident that your machine is genuinely safe.

Why is verifying the effectiveness of risk-reduction measures so important?

Consequences of failing to verify properly

Many serious workplace accidents stem not only from design errors, but also from shortcomings during the assessment process and the verification of safeguards. Even if machine design has been carried out flawlessly and preliminary activities such as machine risk assessment have been completed to a high standard, an incorrect or overly superficial check of how protective devices perform in real conditions can allow potential hazards to go unnoticed. As a result, an employee or operator may be exposed to serious danger, and the company may face severe penalties and reputational damage.

The importance of compliance with legal requirements and harmonised standards

The key reference point for assessing machinery safety is harmonised standards, which set out requirements for the minimum level of safety and the quality of safety systems. Today, for a machine to bear the CE marking, it must meet both the requirements described in the Machinery Directive and other applicable directives (e.g., ATEX if the equipment operates in potentially explosive atmospheres).

Strict adherence to recommendations arising from standards (such as ISO 12100, EN ISO 13849-1 or EN 62061) not only increases the level of safety, but also simplifies legalisation procedures (issuing the declaration of conformity) and minimises potential legal risk.

Key stages in verifying the effectiveness of risk-reduction measures

Documentation review

The process of verifying effectiveness begins with checking whether all entries in the design documentation and risk assessment records are consistent and complete. The documentation should include:

1. Results of the earlier risk assessment (including a description of the nature of the hazards and the risk-reduction measures).
2. Descriptions of the technical solutions used: guards, light curtains, emergency stop devices, etc.
3. Evidence of compliance with the relevant standards and regulations (including test reports, approvals, certificates).
4. Detailed descriptions of the scope of operating activities, as well as procedures to follow in emergency situations.

If there are gaps in the documentation (e.g., no explanation of how a given safety system is intended to function in practice) or information about specific tests is missing, these should be added. It is also important to confirm that the documentation matches the actual technical solutions—during machine build projects, changes are sometimes introduced in the final version that do not always make it into the original documentation.

Design review against harmonised standards

Before moving on to practical testing of the machine, it is worth consulting the harmonised standards and checking whether the design assumptions and the safety mechanisms used meet their requirements. You should verify, among other things:

• The type of guards and their effectiveness (e.g., fixed guards, interlocking guards with a monitoring system, adjustable guards).
• Safety-related control systems—whether their architecture (PLr, SIL, etc.) matches the required level.
• The placement and ergonomics of protective devices (e.g., emergency stop buttons, limit switches).
• Any documentation provisions relating to hazard zones (including EX zones, if an ATEX area is involved).

At this stage, support from specialists is often essential (for example, from a design office) to help assess the design for compatibility with the latest requirements and industry guidelines.

Testing under real operating conditions

The most reliable step is to verify how the machine performs in its intended working environment. These tests are carried out to confirm:

1. The effectiveness of guards and other protective devices:
   • Do the guards prevent access to hazardous areas while the machine is operating?
   • Do light curtains reliably detect the presence of a person?
   • Do interlocking systems stop the machine within the required time?
2. Correct operation of safety-related control systems:
   • Do position sensors, emergency stop devices, and other detection components actually trigger the required responses?
   • Can the machine return to normal operation only after the hazard has been removed and the appropriate restart conditions have been met?
   • Is there logical consistency between the automation modules and the safety components?
3. Compliance with ergonomics and operator procedures:
   • Do operators have safe access to the controls?
   • Is there any possibility of unintended machine start-up?
   • Are the start-up, emergency stop, and restart procedures properly described, easy to understand, and followed in practice?

Depending on the results of real-world testing, design changes may be necessary. Follow-up tests should confirm that the implemented corrections effectively eliminate the identified nonconformities.

Audits and inspections by independent bodies

In industrial practice, a common and recommended approach is to invite an independent expert body to carry out a safety assessment.

An external machine safety audit can help identify errors and nonconformities that the engineers involved in the project may have missed. This perspective is often invaluable for final confirmation that the safeguarding system has been designed and implemented to the highest standards.

Criteria for assessing the effectiveness of risk reduction measures

Level of risk reduction

The primary indicator of how effective safeguards are is the level of risk reduction they provide. Both standards and the risk assessment process itself allow an acceptable level to be determined (PLr or SIL). Verification should demonstrate that the installed protective measures actually achieve the required level. If they do not, it is necessary either to use more advanced safety technologies or to implement additional organizational measures.

Reliability and long-term maintainability

A safety system must not only be designed to operate in an emergency, but also meet reliability requirements throughout its service life. This means regular inspections, maintenance, and periodic testing are necessary. Verification in this context involves checking whether a given risk reduction measure can be maintained in the required condition (e.g., frequent sensor calibration, checking the condition of wiring and contacts).

Clarity and ease of use for the operator

Even the most advanced safety system can prove ineffective if operators do not know how to use it or how to respond to indicated hazards. For this reason, verification should also include:

• Training for personnel operating the equipment.
• Clear labeling of control and protective components.
• Simple, easy-to-understand procedures (e.g., start/stop sequences, the ability to quickly isolate the machine in the event of a failure).

Most common issues and mistakes in the verification process

1. Overly superficial assessment of safeguard functionality – for example, only visually checking that guards are installed, without dynamic testing or measuring stopping time.
2. Lack of integration between safety systems and the machine control system – as a result, safeguards work only in theory, and in practice may be bypassed or deactivated.
3. Insufficient documentation confirming compliance with standards – missing test reports or test records can make it difficult to obtain the CE mark and a formal declaration of conformity.
4. Failure to consider the operating environment – a machine may work correctly in a laboratory, but in demanding production conditions (dust, vibration, high temperature, ATEX zone, etc.) the safety system is often more exposed to failures and errors.

The importance of modernization and continuous improvement

In today’s industrial sector, machines are frequently upgraded. Changes may range from a complete redesign to adapting existing solutions to new production requirements. Any such upgrade makes it necessary to re-check the effectiveness of the risk-reduction measures. Even when introducing minor modifications (e.g., installing a new vision camera, changing the controller, adding a new production line module), you should verify:

• Whether new hazards arise as a result of the new functions.
• Whether the existing safety measures are still adequate and work correctly with the new components.
• Whether additional compliance testing against current standards is required.

Only a positive outcome of this re-assessment authorizes continued operation or the issuance of updated documentation (a declaration of conformity).

Example verification methods and tools

Checklist

This is one of the most basic tools, yet highly effective for structuring a review. A well-designed checklist makes it possible to assess individual safety areas step by step:

• Have all hazardous parts of the machine been properly guarded?
• Are emergency devices (emergency stop, safety switches) easy to access and clearly marked?
• Is the documentation complete, up to date, and consistent with the actual condition of the machine?

HAZOP analysis

This methodology is widely used in the process industry, but it can also be applied to machine assessment. HAZOP involves a systematic review of each stage of the process and identifying possible deviations from the design intent that could lead to hazardous situations. When verifying machine safety, it helps uncover weak points in control systems or in the human–machine interface.

FMEA analysis (Failure Mode and Effects Analysis)

In the safety context, FMEA analysis focuses on identifying potential failure causes (so-called failure modes), their effects, and assessing how severe the consequences could be (severity), how often they may occur (occurrence), and whether they can be detected (detection). Verification based on FMEA makes it possible to check whether the installed risk-reduction measures effectively address the most critical failure scenarios.

SAT and FAT acceptance tests

In large machine and production-line projects, FAT (Factory Acceptance Test) and SAT (Site Acceptance Test) are used. The first is carried out before the finished machine is shipped from the manufacturer’s plant; the second is performed at the destination site, after integration with the production system. Safety verification is an important part of these tests, helping confirm that the equipment meets the contractually agreed requirements as well as safety requirements.

Documenting verification results

After the verification process is complete, it is essential to document the results thoroughly. Typically, a report is prepared, and it should include:

1. Description of the methodology and scope of verification – e.g., which tests and analyses were performed and on what basis the evaluation criteria were defined.
2. Results with photographs and measurements – e.g., whether the emergency stop time falls within the limits assumed by the standard, and what the sensor tolerances are.
3. Conclusions and recommendations – whether the safeguards are sufficient, whether changes are required, and which of them are a priority.
4. Signatures of responsible persons – both those who carried out the verification and those who supervised it.

Such a report is invaluable support in the event of external audits or any potential accident investigations.

Safety verification vs. the CE marking and the declaration of conformity

For equipment to be placed on the market within the European Union, it must bear the CE marking and be accompanied by a declaration of conformity. Issuing the declaration requires, among other things, meeting the essential requirements set out in regulations (primarily the Machinery Directive or the new EU Machinery Regulation) and confirming (based on documentation and tests) that the risk has been reduced to an acceptable level.

Verifying the effectiveness of risk-reduction measures is therefore an integral part of the certification process and conformity assessment. If a manufacturer or importer fails to carry out a robust verification process, serious doubts may arise as to whether the equipment has been correctly marked. In extreme cases, this may result in the withdrawal of the declaration of conformity and the need to remove the product from the market.

Carrying out thorough verification not only helps protect employees’ health and lives, but also strengthens the image of a reliable manufacturer and helps avoid legal consequences. Keep in mind that, in an era of rapidly changing regulations and fast-paced technological development, it is worth staying up to date with industry developments and making use of professional support offered by experts and industry portals.