Technical Assessments

Technical assessments are, in practice, the link between design, installation, operation and demonstrability. They are often required when uncertainty arises: may this item of equipment be used in this zone? Is this modification still acceptable? Does this older installation still meet the requirements? May a component be replaced? Is a temporary arrangement safe? Or does the selected type of protection still correspond with the actual process conditions? A good technical assessment is therefore not an informal opinion from a specialist, but a substantiated judgement on suitability, safety and controllability within the context of explosion protection.

The methodology always starts with a precise definition of the assessment question. In practice, this is more important than is often assumed. The question “is this safe?” is too general. A robust assessment first makes clear what is being assessed: an item of equipment, an installation part, a type of protection, a modification, a repair, a temporary arrangement, a process condition, a deviation, an inspection finding or a documentation gap. The context in which the assessment is carried out must then be defined. A motor in Zone 2 requires a different assessment from the same motor in Zone 1. A sensor in a dry gas atmosphere must be assessed differently from a sensor in a dusty, humid or corrosive environment. An older installation that has been operating for years cannot be assessed in exactly the same way as newly installed equipment, but it must still remain demonstrably safe for continued use.

A good technical assessment therefore starts with the facts. Which zone applies at the location? Which explosive atmosphere may be present? Is the risk related to gas, vapour, mist, a dust cloud or a dust layer? Which gas group, dust group, temperature class, maximum surface temperature and EPL are required? What is the actual ambient temperature? Are there external influences such as moisture, corrosion, vibration, dust loading, mechanical stress, cleaning, UV exposure, chemicals or elevated ambient temperatures? Which documentation is available: certificate, EU Declaration of Conformity, UKCA documentation, manufacturer’s instructions, datasheet, nameplate, inspection report, hazardous area drawing, Explosion Protection Document, DSEAR assessment, intrinsic safety calculation, repair report or manufacturer’s statement? Without these details, a technical assessment quickly becomes an assumption rather than a defensible judgement.

The core of the assessment is the comparison between requirement and reality. The requirement follows from the hazardous area classification, the Explosion Protection Document or DSEAR assessment, the relevant legislation, technical standards, manufacturer’s documentation and operating conditions. Reality is determined by what has actually been installed, how it is used, how it has been maintained and what condition it is in. This is exactly where many deviations arise. On paper, an item of equipment may be suitable, but in the field an incorrect cable gland has been used. The certificate may contain specific conditions of use, but those conditions were never incorporated during installation. An enclosure may have the correct Ex marking, but the actual ambient temperature on site may be outside the permitted range. An Ex d enclosure may still be installed, but the flamepath may be damaged, corroded or treated with an unsuitable sealing compound. An Ex e terminal compartment may be certified, but the terminals may be contaminated, loose, thermally stressed or installed outside the terminal approval limits. An Ex i circuit may appear intrinsically safe, but cable capacitance, inductance, segregation or entity parameters may never have been rechecked after a modification.

Experience shows that the best technical assessments do not look only at the individual component, but at its function within the overall system. Equipment may be suitable in itself, yet become unsuitable because of the way it is applied. A fan in a dust extraction system must not only be electrically suitable; mechanical ignition sources, rubbing, imbalance, material selection, dust deposits, bearing monitoring and spark generation must also be considered. A pump in a solvent line must not only have the correct marking; dry running, cavitation, seal system, earthing, temperature development and maintenance condition are equally important. A temporary mobile installation may appear technically sound, but due to cable routing, earthing, working method and positioning in the hazardous area, the risk may still be insufficiently controlled. A technical assessment must therefore always consider the relationship between equipment, process, environment and use.

In the chemical industry, technical assessments often concern modifications, equipment suitability, process conditions and deviations from design documentation. Particular attention must be paid to the medium, temperature, pressure, vapour formation, gas group, corrosion, seals, sampling, pumps, valves, instrumentation and ventilation. A modification that appears mechanically small may be significant from an explosion protection perspective. A different solvent may have a lower ignition temperature. A higher process temperature may influence the hazardous area classification. A new seal may change the likelihood of release. A replacement motor may appear electrically suitable, but may be unsuitable thermally or in terms of EPL. In chemical installations, a technical assessment is only strong when it is linked to Management of Change and process safety. Otherwise, only the component is assessed, while the real impact lies in the process.

In the food, feed and powder industries, technical assessments often focus on dust behaviour, mechanical equipment and constructional safety. Many questions concern mixers, elevators, filters, screw conveyors, sieves, mills, cyclones, extraction systems, silos and dust layers. An electric motor may correctly be designed as Ex t, while the machine it drives may still become an effective ignition source due to friction, bearing failure, foreign objects or overheating. A filter may have explosion venting, but if explosion isolation is missing or incorrectly applied, propagation into the installation may still be possible. An industrial vacuum cleaner, mobile extraction unit or temporary installation may be useful for housekeeping, but it must be suitable for the dust, the zone and the electrostatic risks. In this sector, experience is essential because the technical assessment must not stop at electrical equipment. Mechanical ignition sources and dust deposits often determine the real risk.

In pharmaceuticals and fine chemicals, technical assessments are often linked to variation. New products, temporary test set-ups, mobile equipment, small batches, laboratory arrangements, drying processes and cleaning methods change regularly. The question is therefore not only whether an item of equipment is suitable, but whether it remains suitable in all relevant use scenarios. A mobile pump that is suitable for one solvent is not automatically suitable for another solvent with a lower ignition temperature or a different gas group. A temporary hose may be unsuitable from an electrostatic point of view. A pilot plant, because of its small scale, may involve many manual operations that do not occur in a fixed production installation. A good technical assessment in this sector must therefore be flexible, but strict in its technical justification. Temporary must never mean outside the explosion protection assessment.

In wastewater treatment plants, biogas installations and waste processing facilities, technical assessments often concern older installations, limited documentation, corrosion, moisture, methane, hydrogen sulphide and outdoor installation. The first question is often not whether everything was built according to the latest design practice, but whether the installation can still be operated demonstrably safely today. An older motor, control cabinet, sensor or cable connection may have operated without problems for years, but due to corrosion, moisture ingress, damaged cable glands or missing marking, it may no longer be defensible. In biogas installations, gas composition, condensate, leakage points, ventilation, compressors, gas trains and flares must also be considered. A technical assessment creates particular value here when it distinguishes between immediately unacceptable deviations, repairable deficiencies and documentation gaps that undermine demonstrability.

In energy systems, utilities, battery rooms and battery charging areas, technical assessments often revolve around hydrogen, ventilation, electrical installations, charging behaviour and room use. Typical questions include whether a battery charging area must be classified as a hazardous area, whether the ventilation is sufficient, whether equipment near the battery is suitable, whether switching equipment is located outside the risk area and whether maintenance activities are adequately controlled. Not every battery charging room automatically has to be classified as an ATEX or DSEAR hazardous area, but a technical assessment must clearly justify why the situation is safe. With modern energy systems, standby power installations and battery storage, the assessment becomes broader. Explosion protection then interfaces with electrical safety, fire safety, ventilation, detection, operational availability and maintenance. An isolated assessment of only the Ex zone is too narrow.

In storage, transfer and logistics, technical assessments often concern loading and unloading points, pumps, hoses, IBCs, tank bunds, earthing, bonding, vapour formation and temporary storage. Here, the technical installation and the working method are closely interconnected. A pump may be suitable, but if the hose is not conductive or the earthing clamp is not used, the risk remains. A filling point may be correctly designed, but when packaging is changed, filling velocities are increased or open filling is introduced, a different electrostatic and vapour-related risk arises. A technical assessment must therefore assess not only equipment, but also activities. In this sector, actual practice is often more decisive than the design document.

In manufacturing industries, technical assessments are often local and highly practical. Spray booths, cleaning baths, degreasing stations, bonding processes, printing processes, woodworking, metal dust, plastic dust and additive manufacturing require an assessment close to the workplace. Companies in this sector do not always see themselves as subject to ATEX or DSEAR duties, which means local risks are sometimes recognised too late. A technical assessment must then clarify whether local extraction is sufficient, whether equipment is suitable for vapour or dust, whether dust layers can form, whether electrostatic charging is possible and whether maintenance or cleaning introduces new risks. The strength of the assessment lies in translating the conclusions into practical measures for operators, maintenance personnel and supervisors.

The result of a technical assessment is achieved when the conclusion is formulated clearly. A good judgement does not simply state “acceptable” or “not acceptable”. It explains under which conditions something is acceptable, which limitations apply, which measures are required and which documentation must be updated. Sometimes the conclusion is that the equipment is suitable as applied. Sometimes it is suitable only under conditions, for example only within a specific ambient temperature range, only with a particular cable gland, only with additional earthing, only with functioning ventilation or only outside a defined operating mode. Sometimes the equipment is technically not defensible and must be replaced, modified or taken out of service. This clarity is necessary to avoid discussion and false confidence.

A good technical assessment also distinguishes between safety, conformity and demonstrability. A situation may appear technically safe, but be insufficiently demonstrable from a documentation perspective. Equipment may be correctly installed, but without a legible nameplate, certificate or traceability, it may not remain defensible. Conversely, the documentation may appear complete, while the physical condition is unacceptable due to corrosion, contamination or incorrect installation. In practice, these three lines must be assessed together. Safety concerns the actual risk. Conformity concerns compliance with legislation, standards and manufacturer’s conditions. Demonstrability concerns the ability to prove that safety and conformity during an audit, inspection, insurance review or regulatory visit.

The documentation of the technical assessment must therefore be concise but complete. It must clearly record the question, scope, assumptions, documents used, relevant legislation and standards, observations, assessment, risk judgement, conclusion and required measures. A technical assessment without clear assumptions is difficult to defend later. An assessment without photographs, location details, type data or references to certificates is difficult to trace. A conclusion without conditions can be applied incorrectly. The objective is not a thick report, but a technically precise document that enables the company to make a sound decision.

From experience, the best technical assessments are those that reduce uncertainty. Management wants to know whether a risk is acceptable and what investment is required. Engineering wants to know whether a design or modification can proceed. Maintenance wants to know whether repair, replacement or additional inspection is necessary. HSE wants to know whether the Explosion Protection Document, DSEAR assessment, hazardous area classification or verification dossier must be updated. Production wants to know whether it can continue operating safely. A good technical assessment brings these interests together without weakening the technical judgement.

Technical assessments are therefore not isolated expert opinions, but decision points within explosion protection management. They prevent small deviations from developing unnoticed into structural risks. They also prevent companies from replacing equipment or investing unnecessarily when a situation is technically defensible. The value lies in the balance: not approving too lightly, but also not rejecting unnecessarily conservatively. The judgement must fit the zone, the substance, the installation, the applicable standard, the manufacturer’s conditions and the actual operating practice.

A technical assessment is successful when the company knows where it stands afterwards. Is the situation acceptable, acceptable under conditions, temporarily controllable, repairable or unacceptable? Which measure must be taken, by whom and with what priority? Which documents must be updated? Which inspection or verification is required afterwards? When these questions are answered clearly, the result is what companies need: technical certainty, better decision-making, fewer hidden risks and a stronger dossier for audits, insurers, regulators and internal safety reviews.