About this program

This page is a 10-minute orientation. For full procedural details, consult the cited standards directly.

1. What HACacare does

HACacare is a multi-module web application for engineers working with hazardous areas and explosion prevention. Each module implements the procedure of a specific published standard, with every numeric output traceable to the clause that defines it and every substance property tagged with its data source.

The six modules available today are:

• Gas & Vapour Zone Classification — following IEC 60079-10-1:2020. Classifies a release source into Zone 0 / 1 / 2 / non-hazardous, calculates the hazardous distance, and produces an XLSX report whose sheets match the standard's data-sheet layout (Tables A.1 and A.2).
• Inerting — following CEN/TR 15281:2022. Three sub- calculations cover the most common inerting scenarios: swing inerting (combined pressure / vacuum), flow-through purging, and prevention of air diffusion down a vent pipe or manhole. Each calculator produces a downloadable PDF or XLSX calculation note.
• Battery Rooms — Stationary Batteries — following IEC 62485-2:2010. Calculates the minimum ventilation flow rate, required natural-ventilation opening area and safety distance for rooms containing stationary secondary batteries (lead-acid vented, VRLA, NiCd). Includes an optional adequacy check against existing extraction capacity and a Section 9.2 attention-item checklist. Each calculation produces a downloadable PDF or XLSX calculation note.
• Traction Battery Charging Areas — following IEC 62485-3:2014. Calculates the minimum ventilation flow rate, natural-ventilation opening area, free volume adequacy and the fixed 0.5 m safety distance for forklift and traction battery charging areas (lead-acid, VRLA, NiCd). Covers regulated and unregulated chargers, and simultaneous charging of multiple vehicles. Each calculation produces a downloadable PDF or XLSX calculation note.
• Spray Booth Zone Classification — following EN 16985:2018. Four calculation blocks cover the four spray booth scenarios in the standard: liquid / solvent paints (§C.3), powder coatings (§C.6), water-based paints with co-solvent (§C.7), and purge-time estimation (§C.8). Results are stored in a project and an XLSX report covering all four blocks is available for download.
• Dryers & Ovens — Safety Ventilation — following EN 1539:2015. Covers Type A dryers (explosion prevention by ventilation) in two configurations: chamber dryers using Method A (rapid evaporation, Annex A.1.2) and continuous flow dryers (Annex A.2). Three calculation modes are provided: assessment of an existing dryer (given Q and g_max, determine the operating range), design of required ventilation (Q_min for a target range), and design of maximum admissible solvent load. Results are stored in a project and an XLSX report is available for download.

2. Gas & Vapour Zone Classification (IEC 60079-10-1:2020)

For each release source you describe, the module calculates the expected mass release rate, determines how the surrounding ventilation dilutes the resulting vapour, classifies the resulting zone, and estimates the hazardous distance. Every decision is recorded in an audit log that travels with the calculation through to the XLSX report.

2.1 Release rate

Depending on the scenario, the program selects one of four formulas from Annex B of IEC 60079-10-1:2020:

A chained scenario (B.1 → B.6) is available when a liquid leaks onto a surface and forms a pool whose evaporation rate is the relevant release rate. The orchestrator decides whether to use the leak rate or the pool-evaporation rate based on whether the pool reaches steady state during the leak.

2.2 Vapour density and buoyancy

The vapour density relative to air drives both the dilution model and Table C.1 lookups for natural ventilation. Releases are grouped into three buoyancy classes:

• Lighter than air (relative density < 0.8)
• Neutral (0.8 – 1.2)
• Heavier than air (> 1.2)

For pool evaporation, the standard uses a dedicated row in Table C.1 regardless of the vapour density.

2.3 Ventilation

Three ventilation modes are supported:

2.4 Dilution

The dilution effectiveness is determined from IEC 60079-10-1 Figure C.1: a chart of u_w versus Q_C, where Q_C is the characteristic volumetric release derived from the release rate, vapour density, and lower flammable limit (LFL). The chart's two boundary lines separate the three dilution levels:

• High — concentration falls below LFL very rapidly
• Medium — concentration falls below LFL within an acceptable distance
• Low — concentration may persist near or above LFL

The program reports both the computed Q_C and how close u_w is to the boundary lines, so you can judge the margin of safety.

2.5 Zone classification

The combination of grade of release (continuous / primary / secondary), dilution, and availability of ventilation (good / fair / poor) maps to a zone type via IEC 60079-10-1 Table D.1. Possible outcomes:

• Zone 0 — explosive atmosphere is present continuously or for long periods
• Zone 1 — likely to occur in normal operation occasionally
• Zone 2 — not likely to occur in normal operation; if it does, only briefly
• Non-hazardous (NE — negligible extent) — the explosive atmosphere, if it occurs at all, is so small in extent and duration that no zone classification is required.

A few cells in Table D.1 require user judgement (e.g. primary + low dilution: Zone 1 by default, but Zone 0 if the ventilation is so weak that an explosive atmosphere is virtually continuous). In those cases the program presents a decision page with the standard's options and the rationale for each.

2.6 Zone size (hazardous distance)

The hazardous extent is estimated from IEC 60079-10-1 Figure D.1, which provides three empirical dispersion curves on a log–log chart of hazardous distance vs. Q_C:

The program selects the model automatically from the release type, sonic / subsonic flag, and relative vapour density. Above the chart's upper Q_C bound (≈ 12 m³/s) the chart cannot be extrapolated and the program reports an "out of range" warning. Below the curve's lower domain, the result is clamped to the chart's minimum displayed distance (1.5 m for the heavy gas curve, 1.0 m for the diffusive and jet curves), in accordance with IEC 60079-10-1:2020 Figure D.1.

3. Inerting (CEN/TR 15281:2022)

The inerting module supports three calculation methods. Each has its own page; each produces a downloadable calculation note (PDF or XLSX) suitable for filing in an explosion-protection document.

3.1 Swing inerting — combined pressure / vacuum (Annex A)

Calculates how many pressurisation/venting (or evacuation/backfill) cycles are required to drive the oxygen content of a vessel below a target — typically the Maximum Allowable Oxygen Concentration (MAOC, derived from the substance's Limiting Oxygen Concentration LOC).

The user enters a lower swing pressure (typically a vacuum) and an upper swing pressure (typically an overpressure). Each pressure field accepts bar absolute (default), bar gauge or mmHg. A unified UI handles all three textbook cases:

• Pure pressure swing — lower pressure left at atmospheric.
• Pure vacuum swing — upper pressure left at atmospheric.
• Combined — both extremes are non-atmospheric. CEN/TR 15281 §4.3.3.1 explicitly permits this combination, and mathematically the formula depends only on the absolute pressure ratio P₁/P₂.

Outputs: the exact number of cycles required (Formula A.2), the O₂ concentration achieved after the rounded-up integer number of cycles (Formula A.1), the pressure ratio R, and a cycle-by- cycle table. The MAOC helper applies the rules of §4.4.5.3.1 automatically once the LOC is given.

3.2 Flow-through purging (Annex B)

Inert gas is allowed to flow through the equipment until the target oxygen content is reached. Three calculation modes:

• Required purge time for a given vessel volume and flow rate (Formula B.1).
• Remaining O₂ concentration after a given time at a given flow rate (Formula B.2).
• Required flow rate to reach the target in a given time (Formula B.3).

A safety factor F accounts for imperfect mixing (CEN/TR 15281 Annex B): F = 1 for plug-flow pipework, F = 2 for a vessel with diametrically opposite inlet and outlet, F = 5 when inlet and outlet are not opposite. A custom value can also be entered for in-between geometries.

3.3 Prevention of air diffusion down vent pipes or manholes (Annex D)

Calculates the inert-gas superficial velocity that must be maintained up an open vent pipe — or, by extension, through an open manhole or work hatch during charging — to stop atmospheric air diffusing back into an otherwise inerted vessel.

The empirical Formula D.1 is implemented as published. Two branches:

• Nitrogen (m = 28). The (28/m)^N factor is identically 1, so the Figure D.1 exponent N is irrelevant and is not consulted. The chart's 4–30 inch diameter range therefore does not constrain the calculation either.
• Other purge gases (m ≠ 28). The exponent N is read from Figure D.1; diameters outside 4–30 inch are rejected, and diameters above 24 inch carry an "extrapolated" warning.

A practical note appears for openings above 30 inch (≈ 760 mm, typically nitrogen-only manholes): the calculated superficial velocity cannot reliably be maintained from a single injection point and must be distributed across the opening (typically ≥ 3 points). Sizing the injection geometry is left to the mechanical designer; the program provides only the required velocity and the equivalent volumetric flow.

4. Battery Rooms — Ventilation & Explosion Protection (IEC 62485-2:2010)

The battery room module implements the ventilation and explosion-protection requirements of IEC 62485-2:2010 for stationary secondary batteries. It covers lead-acid vented, lead-acid VRLA (valve-regulated) and NiCd vented battery types.

4.1 Minimum ventilation flow rate Q (Section 7.2)

The hydrogen volume that must be removed per unit time is calculated from the gas-evolution current I_gas (Table 1 of the standard, including the safety factors f_g and f_s):

Q = 0.05 × n × Igas × Crt × 10⁻³  [m³/h per string]

where n is the number of cells per string (or per monobloc battery), I_gas is the Table 1 value in mA/Ah, and C_rt is the rated capacity in Ah. When the maximum room temperature exceeds 25 °C (up to 40 °C) a correction factor of 1.095 is applied to the hydrogen volume factor q, per the Section 7.2 remark. The calculator computes Q per string and the total for all strings in the room, for both float-charge and boost-charge modes.

4.2 Natural ventilation opening area A (Section 7.3)

For naturally ventilated rooms, the minimum free area of both the inlet and outlet openings (assumed on opposite walls or ≥ 2 m apart) is:

A = 28 × Q  [cm²]

For mechanically ventilated rooms only the required flow rate Q is reported; the standard (Section 7.4) additionally requires an interlock between the charger and the ventilation system, which the calculator flags as an attention item.

4.3 Safety distance d (Section 7.7 / Annex B)

The safety distance defines the zone within which sparking, arcing or glowing devices (surface temperature > 300 °C) are prohibited. It is derived from Annex B assuming a single shared vent opening for all cells in a string (worst-case shared-venting model):

d = 28.8 × ∛(n × Igas × Crt)  [mm]

The worst-case I_gas value (boost charge, where applicable) is always used for the safety distance. The temperature correction factor is applied to the cube root for consistency with the Q derivation.

4.4 Adequacy check and Section 9.2 attention items

If the user supplies the existing extraction capacity (m³/h), the calculator compares it against the required worst-case Q and reports whether it is sufficient or insufficient, and by how much.

The result page always shows a set of non-computational attention items drawn from IEC 62485-2:2010 Section 9.2 (structural loads, door specification, floor impermeability, electrostatic resistance, escape path width, battery-type separation, etc.). These are reproduced in the downloadable calculation note so they travel with the calculation into the explosion-protection document.

5. Traction Battery Charging Areas (IEC 62485-3:2014)

The traction battery module implements the ventilation and explosion-protection requirements of IEC 62485-3:2014 for charging areas serving forklifts and other electric vehicles. It covers vented lead-acid, VRLA and vented nickel-cadmium traction batteries, charged on or off the vehicle.

5.1 Minimum ventilation flow rate Q (Section 6.2.2)

The required ventilation flow per battery is:

Q = 0.055 × n × Igas  [m³/h per battery]

where n is the number of cells per battery and I_gas is the gassing current in A. The constant 0.055 incorporates the standard dilution factor (v = 24), hydrogen volume (q = 0.42 × 10⁻³ m³/Ah at 25 °C) and a safety factor s = 5. The formula is valid at 25 °C and may be applied without further temperature adjustment up to the maximum battery operating temperature.

Two modes are provided for determining I_gas:

• Known gassing current (Section 6.2.2 a / 6.2.4): the user enters I_gas directly. Applies when using a regulated charger with a known end-of-charge current, or a special / pulse / fast charger for which the charger manufacturer specifies I_gas.
• Unregulated or unknown end-of-charge current (Section 6.2.2 b): the user enters the rated charger output current I_n; the program computes I_gas = 0.4 × I_n.

When multiple batteries are charged simultaneously (Section 6.2.5), the total flow is the sum of the individual requirements: Q_total = n_spots × Q_{per battery}.

5.2 Natural ventilation opening area A (Section 6.3)

A = 28 × Q  [cm²]

Applies to both the air inlet and the air outlet, based on a natural air velocity of at least 0.1 m/s. Openings shall be on opposite walls, or at least 2 m apart on the same wall.

5.3 Free volume adequacy check (Section 6.3)

In naturally ventilated charging areas where the free room volume satisfies V_free ≥ 2.5 × Q [m³], forced ventilation is not required for explosion-protection purposes. If this condition is not met, forced ventilation is mandatory.

5.4 Safety distance (Section 6.5)

A fixed minimum safety distance of 0.5 m applies around the battery — no flames, electrostatic discharge, sparks, arcs or glowing objects are permitted within this zone. The maximum permissible surface temperature of any equipment within the zone is 300 °C.

5.5 Adequacy check and explosion-protection attention items

If the user supplies the existing extraction capacity (m³/h), the calculator compares it against the required Q and reports whether it is sufficient.

The result page always displays a set of non-computational attention items derived from IEC 62485-3:2014 Sections 6.4, 6.5, 9.1–9.5 and 11.1 — covering charger interlock, floor resistance (≤ 100 MΩ to ground), separation from hazardous materials, ignition-source exclusion, electrostatic precautions, access spacing (0.8 m) and required warning labels. These items are reproduced in the downloadable calculation note so they travel with the calculation into the explosion-protection document.

6. Spray Booth Zone Classification (EN 16985:2018)

The spray booth module implements the explosion-prevention and zone- classification calculations of EN 16985:2018 §6 for spray booths using flammable coating materials. Four independent calculation blocks are provided, matching the four main scenarios in the standard:

6.1 Liquid / solvent-based paints (§C.3)

For each solvent substance in the paint, the module checks whether the ventilation is sufficient to keep the maximum steady-state concentration below the k₂ fraction of the LEL (Lower Explosion Limit). The check formula is:

C = ṁ / Q_a = k₁ · ṁ_total / Q_a   [g/m³]

where ṁ_total is the solvent mass flow rate (kg/h × k₃ evaporation factor), Q_a is the supplied ventilation flow, k₁ is the fraction of the throughput that contributes to vapour release (defaults to 1 — conservative), and k₃ is an evaporation factor. The zone classification follows §6.3:

• Zone 1 — inside the booth when C > k₂ · LEL (ventilation inadequate for automatic booths)
• Zone 2 — within 1 m of all booth openings (mandatory regardless of ventilation adequacy)
• Non-hazardous — inside the booth when C ≤ k₂ · LEL (adequate ventilation for manual booths)

Conservative approach: every solvent in the paint is evaluated independently at the full total throughput (k₁ = 1), treating as if the entire paint flow were that single solvent. The worst-case substance (highest C / LEL ratio) governs the verdict.

6.2 Powder coatings (§C.6)

For powder-coating booths the relevant limit is the Minimum Explosible Concentration (MEC) of the powder. The calculation follows the same dilution logic:

C = k₁ · ṁ / Q_a   [g/m³]

The result is expressed as a percentage of MEC (default 10 g/m³ when not known). The zone classification per §C.6 is:

• Zone 22 — inside the booth (dust cloud present during normal operation)
• Pass / Fail — the ventilation adequacy verdict: C ≤ k₂ · MEC

6.3 Water-based paints with co-solvent (§C.7)

Water-based paints still contain a small fraction of organic co-solvent. The module multiplies the total throughput by the solvent weight fraction to derive the effective solvent mass flow rate, then applies the same §C.3 check against the co-solvent's LEL.

ṁ_eff = ṁ_total · f_solvent

The zone classification outcome is the same as for liquid paints (Zone 1 / Zone 2 / Non-hazardous).

6.4 Purge time (§C.8)

After painting stops, the booth must be purged until the concentration falls below the safe level. The purge time is derived from the exponential dilution model:

t_purge = (V / Q_a) · ln(C_initial / C_target)   [min]

where V is the booth volume, Q_a is the ventilation flow, C_initial is the estimated maximum concentration immediately after painting stops, and C_target is the clearing target (typically 25 % of the LEL). If the computed time exceeds 30 minutes, the result carries a warning to consider increasing ventilation.

6.5 Project storage and reports

Unlike the inerting and battery modules, the spray booth module stores its results in a project: calculations for all four blocks are saved under a named project so they can be revisited and updated. When any calculation block has a saved result, an XLSX report covering all completed blocks can be downloaded in one click.

7. Dryers & Ovens — Safety Ventilation (EN 1539:2015)

The dryer / oven module implements the safety ventilation requirements of EN 1539:2015 for Type A dryers — dryers where explosion is prevented by maintaining the flammable vapour concentration below the lower explosion limit. Two dryer configurations are covered:

7.1 LEL temperature correction (Annex D.2)

The lower explosion limit falls with rising temperature. The temperature-corrected LEL at the drying temperature ϑ is:

LELϑ = LEL20 · (1 − ΔLEL · (ϑ − 20))

where Δ_LEL is the temperature dependence of the LEL [/K]. The standard's default when the substance-specific value is unknown is 0.002 /K (= 20 %/100 K, Annex D.3). The corrected LEL governs the admissible concentration for Range 3 operation.

7.2 Operating ranges (Figure 1)

EN 1539:2015 Figure 1 defines three operating ranges by the maximum admissible average concentration C_adm in the dryer exhaust:

Range 1 has the lowest concentration limit but the fewest safety measures; Range 3 permits the highest concentration but demands the most safety systems (Table 2).

7.3 Chamber dryer — Method A (Annex A.1.2)

Method A assumes rapid evaporation: all solvent charged into the dryer evaporates within the drying cycle. The key dimensionless parameter γ is:

γ = Cadm · 293 · V / (geff · (273 + ϑ))  [Formula A.2]

where V is the dryer volume [m³] and g_eff is the effective solvent load after any pre-drying correction [g]. From γ, the time ratio τ = t_o/t_w is obtained from the empirical Formula A.5:

τ = (a + c·γ) / (1 + b·γ + d·γ²)

where the standard constants are a = −2946, b = −3096, c = 3045, d = −5222. The minimum air-exchange time t_w = t_o/τ, from which the minimum exhaust flow is:

Qmin,ϑ = V / tw   [Formula A.8]
Qmin,20 = Qmin,ϑ · 293 / (273 + ϑ)   [Formula A.9]

An optional pre-drying correction applies Table A.1 (surface drying) or Table A.2 (mould / baked-on drying) to reduce the effective solvent load for a given pre-drying time.

Three calculation modes are supported per formula inversion direction:

• Assessment: given Q (actual exhaust flow) and g_max, compute C_actual by inverting Formula A.5 via its quadratic form, then classify into Range 1 / 2 / 3 or inadmissible.
• Design Q: given g_max and target range, compute Q_min.
• Design load: given Q and target range, compute g_max,adm (Formula A.9).

7.4 Continuous flow dryer (Annex A.2)

In a continuous flow dryer the relevant quantity is the maximum steady-state throughput of releasable substances M_max [g/h]. The steady-state concentration in the exhaust is:

C = Mmax / Q20   [Formula A.14]

The required minimum exhaust flow for a target range is:

Qmin,20 = Mmax / Cadm   [Formula A.11]
Qmin,ϑ = Qmin,20 · (273 + ϑ) / 293   [Formula A.12]

Exhaust flows can be entered at 20 °C or at drying temperature; the program converts automatically. The same three calculation modes (assessment, design Q, design load) are available.

7.5 Safety requirements (Table 2)

For each operating range, EN 1539:2015 Table 2 lists the acceptable combinations of protective measures. The program displays all acceptable combinations for the determined range without attempting to check compliance — the engineer selects and documents which combination the installation implements. The safety measures span monitoring of exhaust flow rate (§5.9.2.2.2), vapour concentration monitoring per EN 60079-29-1 (§5.9.2.2.3), exhaust-flow control driven by concentration signal (§5.9.2.2.4), monitoring of input load (§5.9.2.2.5), ignition-source-free equipment Category 3G (§5.9.2.2.6) or Category 2G (§5.9.2.2.7), and explosion relief per EN 14994 (§5.9.2.2.8).

7.6 Method B guidance and project storage

Method B (slow evaporation) cannot be numerically calculated from the standard — compliance is established by concentration monitoring and process evidence. The module's Method B tab provides qualitative guidance and a reference checklist drawn from Annex A.1.3.

Like the Gas & Vapour and Spray Booth modules, the dryer module is project-backed: results for both dryer types are saved under a named project and can be revisited, updated and re-downloaded at any time. The XLSX report covers both calculation blocks and includes the Table 2 safety requirements for the determined range(s).

8. Substance data sources

Whenever you start a calculation by entering a CAS number or name, the program collects substance properties (M, ρ, p_v, LFL, flash point, T-class, ...) by consulting these sources in order:

1. Local database — substances you (or anyone using this installation) have looked up before, plus any manual overrides. Manual values always take precedence over external sources.
2. ISO/IEC 80079-20-1:2017 Annex B Table B.1 — bundled offline reference covering the flammable substances listed in the standard. This is the primary source for ATEX-specific properties (T-class, IIA/B/C group, MESG, LFL, UFL, flash point).
3. PubChem PUG REST API — online physicochemical data (e.g. molar mass, boiling point, density). Used to fill in properties not covered by the ISO reference. Can be disabled via the ZONE_CALC_PUBCHEM_OFF environment variable for offline use.
4. NIST Chemistry WebBook — online thermophysical data (e.g. vapour pressure, specific heat). Consulted for any remaining gaps after the ISO and PubChem lookups.
5. Manual entry — for anything still missing, the program shows you a gap-filling form with helper links to GESTIS and ECHA so you can look up authoritative values.

Every property in the result is annotated with its source. The XLSX report's data sheet (Table A.1 column 15) lists every source consulted for each substance.

The substance database is shared across all users of the same HACacare installation: a property added by one engineer is available to the next without re-querying the external sources. The audit trail (source + retrieval timestamp) is preserved per property, so any reviewer can trace a value back to its origin.

9. User accounts, projects and collaboration

HACacare is gated by user authentication. The landing page and this About page are publicly visible (so a potential user can see what the program does without signing up), but every calculation module requires sign-in.

9.1 Accounts

• Admin-created only. There is no public registration. Accounts are created by an administrator from the Admin page. The very first administrator is created via a one-time bootstrap protected by a setup token configured at deployment.
• Passwords are never stored in clear. Werkzeug's scrypt-based hashing is used. The administrator can reset another user's password but cannot read it.
• Soft deactivation — an account can be deactivated (so it can no longer sign in) without losing the account record or any of the user's data. There is no hard delete in v1.0.

9.2 Projects (in project-backed modules)

The Gas & Vapour Zone Classification, Spray Booth and Dryers & Ovens modules are project-backed. Each user has their own project workspace; a project groups together all the calculations for a real-world installation (a plant, an area, an equipment item). Within a project you can:

• Add, edit and delete calculations.
• Download a structured XLSX report.
• Share the project with other users (see §9.4).

9.3 Templates

Any project can be saved as a template — a reusable starting point for new projects of the same kind (e.g. "standard flange connections at 2 bar with outdoor natural ventilation"). New projects can be instantiated from the template, inheriting its release sources.

9.4 Sharing (co-working)

Sharing is available in all three project-backed modules (Gas & Vapour, Spray Booth, Dryers & Ovens). The owner of a project can share it with one or more other users. A user with whom a project has been shared sees it in their own project list (marked "shared by …") and has view and edit access: they can add, modify and delete calculations, and download the report.

What a sharee cannot do:

• Delete the project itself.
• Manage the sharing list (only the owner can grant or revoke shares).

9.5 Stateless vs. project-backed modules

The inerting, battery room (IEC 62485-2) and traction battery (IEC 62485-3) modules are stateless — calculations are not stored in projects. Each calculation produces a downloadable PDF or XLSX calculation note that you can save locally and attach to your explosion-protection document. Optional header fields (project, equipment / tag, prepared-by) appear on the report.

By contrast, the Gas & Vapour, Spray Booth and Dryers & Ovens modules are project-backed: calculation results are stored server-side in named projects and can be revisited, edited and re-downloaded at any time.

9.6 Admin oversight

Administrators have access to an "All projects" page that lists every project on the platform with its owner. From there an admin can delete a project (with a name-confirmation step, no edit), for clean-up purposes. Admins cannot edit other users' calculation data — they can only view and delete.

10. Units

You can enter any value in the unit you have it in — millimetres, bars, degrees Celsius, vol percent, and so on. The program converts everything to SI internally before evaluating any formula:

• Hole and pool areas → m²
• Pressures → Pa
• Temperatures → K
• Mass flows → kg/s
• Volumetric flows → m³/s
• LFL / UFL → vol/vol fractions
• Densities → kg/m³

On the report and result pages, values are shown back in user-friendly units that match the standard's data-sheet headings (kg/s for release rates, kPa for vapour pressure at 20 °C, °C for temperatures, etc.). The inerting module accepts bar absolute (default), bar gauge or mmHg per pressure field independently.

11. Limitations

The calculations follow the published procedures of their source standards faithfully, but those procedures are themselves approximations of complex physical processes:

• The chart-based dispersion model of IEC 60079-10-1 Figures C.1 and D.1 does not treat wind direction, room geometry, or obstacles beyond the binary obstructed / unobstructed flag. For complex geometries or unusual operating conditions, a more detailed dispersion model (e.g. CFD) is recommended.
• All calculations assume steady-state; no transient release modelling is performed.
• The validity ranges of the dispersion curves are bounded; out-of-range cases are flagged rather than extrapolated.
• Two-phase releases, liquefied gases and foam blanketing are not specifically modelled. The four release equations cover the typical cases addressed by IEC 60079-10-1 Annex B.
• The inerting Formula D.1 is empirical and valid only for O₂ concentrations between 3 % and 6 % v/v; values outside this range produce a result with a "validity range" warning.
• Indoor air-change-rate methods other than the IEC C.2 / EN 16798-7 wind-induced formulas are not built in; for those you need to enter the mechanical Q_a or u_w manually.

Where any of the above matters, the program is intended to inform engineering judgement, not replace it. Cross-check borderline cases against expert review and the source standards.

12. References

• IEC 60079-10-1:2020 — Explosive atmospheres — Part 10-1: Classification of areas — Explosive gas atmospheres. Primary procedural reference for the gas / vapour zone module (Annexes B, C, D).
• CEN/TR 15281:2022 — Potentially explosive atmospheres — Explosion prevention and protection — Guidance on inerting for the prevention of explosions. Primary reference for the inerting module (Annexes A, B, D).
• ISO/IEC 80079-20-1:2017 — Explosive atmospheres — Part 20-1: Material characteristics for gas and vapour classification — Test methods and data. Primary offline substance reference (Annex B Table B.1); PubChem and NIST WebBook used as online fallbacks for properties not listed in the standard.
• IEC 62485-2:2010 — Safety requirements for secondary batteries and battery installations — Part 2: Stationary batteries. Primary procedural reference for the battery room module (Sections 7.2, 7.3, 7.4, 7.7, 9.2 and Annex B).
• IEC 62485-3:2014 — Safety requirements for secondary batteries and battery installations — Part 3: Traction batteries. Primary procedural reference for the traction battery module (Sections 6.2.2, 6.3, 6.4, 6.5, 9.1–9.5 and 11.1).
• EN 16985:2018 — Paint spraying equipment — Spray booths for liquid coating material — Safety requirements. Primary procedural reference for the spray booth module (Sections C.3, C.6, C.7 and C.8).
• EN 1539:2015 — Dryers and ovens in which flammable substances are released — Safety requirements. Primary procedural reference for the dryers & ovens module (Annex A.1.2 chamber Method A, Annex A.2 continuous flow, Annex D.2 LEL temperature correction, Table 2 safety requirements).
• EN 16798-7:2017 — Energy performance of buildings — Ventilation for buildings — Part 7: Calculation methods for the determination of air flow rates in buildings including infiltration. Used for wind pressure coefficients (Table B.7) and discharge coefficient (B.3.2.1) in indoor cross-ventilation calculations, referenced via IEC 60079-10-1 C.5.2.
• EN 1839:2017 — Determination of explosion limits and LOC for flammable gases and vapours. Referenced by CEN/TR 15281 for the LOC concept.
• EN ISO 28300:2008 — Venting of atmospheric and low-pressure storage tanks. Referenced by CEN/TR 15281 Annex C for displacement inerting flow rates.
• PubChem — National Library of Medicine, online chemistry database, accessed via the PUG REST API.
• NIST Chemistry WebBook — National Institute of Standards and Technology, online thermophysical properties database.
• GESTIS Substance Database — DGUV (Germany). Linked from the gap-filling form for manual lookups.
• ECHA — European Chemicals Agency. Linked from the gap-filling form.

13. Disclaimer