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 nine 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).
• Qualitative Hazardous Area Classification — following IEC 60079-10-1:2020 Annex F. The schematic approach: no release-rate calculation required — the engineer supplies grade, dilution and ventilation availability; the zone type is read from Table D.1. Generates a flowchart PNG (Figures F.1–F.4 decision path) per release source, suitable for copy-paste into documentation. Project-backed with per-project company logo support.
• 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 (Annex C.2), powder coatings (Annex C.3), water-based paints with co-solvent (Annex C.2, reused — the standard has no separate formula), and purge-time estimation (Annex I, a distinct health-exposure calculation). Liquid/water checks verify the resulting concentration against the §4.9.2.1 compliance ceiling for the booth type and confirm that the interior zone this produces still matches the zone declared by the booth manufacturer. 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.
• Natural Gas HAC — following IGEM/SR/25 Edition 2 (2013). Table lookup for outdoor natural gas installations: Table 1 (freely ventilated) and Table 2 (congested / confined) by operating pressure and site conditions. Covers pipe joints, flanges, valve glands, valve end connections, regulators, and vent pipe terminations (Appendix 9, Figs 13–16). Determines Zone 0 / 1 / 2 or NE (Negligible Extent) per grade of release. Includes Xs (Zone 1 sphere per clause 5.2.3), Xb (vent pipe dispersion radius per Table 18 for regulators), and Appendix 9 vent pipe zone extents (Tables 17–27). Results are stored in a project; the XLSX report separates standard sources and vent pipe terminations onto dedicated sheets.
• Electrostatic Hazards Evaluation — following IEC/TS 60079-32-1:2013+A1:2017 Annex F. Walks Figure F.1's systematic electrostatic evaluation flowchart: an entry decision (is charging expected at all?) followed by an exclusive choice between the conductive/dissipative materials path and the insulating materials path, each terminating in one of five named discharge types (corona, spark, propagating brush, cone, brush) or "test passed". Every question and referenced table (capacitance limits, surface-size limits, transferred-charge limits) is reproduced verbatim or as a real table, with a plain-language explanation alongside. Stateless — no project — and identical on both views (see §1.1). Produces a downloadable, editable block-diagram report (PPTX).

1.1 Two views: HAC Engineering and Site Engineering

After signing in, you choose which view to work in — and can switch at any time from the navigation bar. Both views run the same underlying calculations; only the presentation and starting point differ.

• HAC Engineering — the full set of tools listed above, for engineers producing a new classification, inerting design, battery room design, spray booth or dryer classification, or a natural gas installation assessment from scratch.
• Site Engineering — a reduced, simplified view of five of the modules above (Inerting, Battery Rooms, Traction Battery, Spray Booth, Dryers & Ovens), for engineers who maintain or check an existing installation rather than design a new one: verifying that an existing setup still meets requirements, previewing the effect of a planned change before a full management-of-change review, or consulting a full operating checklist drawn from the standard (downloadable as a formatted document) — maintenance, PPE, regular inspection routine, labelling — not just explosion protection. For Spray Booth specifically, this also includes verifying that a booth's manufacturer-declared interior zone still matches what the currently installed ventilation would produce (§7.1) — a consistency check, never an independent zone classification. For Dryers & Ovens, only the assessment check (existing installation vs. a target operating range) is offered, not the design calculations, and only for Type A dryers — Type B (inertised) dryers and chamber Method B (slow evaporation, which has no calculation method in the standard) are out of scope on both views (§8.7).
• Electrostatic Hazards Evaluation is a third case: it has no separate reduced view at all — the same page is linked identically from both HAC Engineering and Site Engineering, since the module (a flowchart-driven checklist with inline explanations) already reads the same way to both audiences.

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.

2.7 Background concentration check (Annex C.3.6.2)

For indoor scenarios, IEC 60079-10-1 Annex C.3.6.2 (informative) requires a check on whether the background concentration of vapour in the room could accumulate to a hazardous level — i.e. whether the general dilution ventilation is sufficient to keep the mean concentration below 25 % of the lower flammability limit (LFL). The program implements this as an optional step on the result page, active only when the ventilation mode is indoor (natural wind-induced or mechanical).

The steady-state background concentration X_b is calculated from the volumetric release rate Q_g [m³/s] and the ventilation airflow Q_a [m³/s]:

X_b = f × Q_g / Q_a

where f is the inhomogeneity factor that accounts for imperfect mixing of the ventilation air with the released vapour:

The critical threshold is X_crit = 0.25 × LFL (25 % of the lower flammability limit). If X_b > X_crit, the program overrides the dilution degree to LOW and re-runs Table D.1 classification, regardless of what the Figure C.1 chart indicated. This can promote the hazardous zone category (e.g. NE → Zone 2, or Zone 2 → Zone 1). Unchecking the background-concentration checkbox on the result page reverts immediately to the original C.1 result.

Optionally, the user can supply the room volume V₀ [m³]. When V₀ is provided and the background check has triggered an override, the program also computes the persistence time per Annex J.3:

t_d = (f / C) × ln(X_b / X_crit)

where C = Q_a / V₀ [s⁻¹] is the ventilation rate constant. t_d is the estimated time after the release stops for the background concentration to fall below X_crit. Annex J.3 notes that, when t_d is significant, the hazardous zone should encompass the entire room volume for the duration of t_d. The result is reported in hours and is included in the Notes / remarks column of the downloaded XLSX report.

3. Qualitative Hazardous Area Classification (IEC 60079-10-1:2020 Annex F)

For locations where the physical boundaries of the hazardous area are already defined by the equipment geometry (e.g. the interior of a vessel, a collection sump, a mixer) the engineer does not need to calculate release rates or zone extents. Annex F provides a schematic (flowchart) procedure that determines the type of hazardous zone directly from three qualitative parameters.

3.1 Inputs

The module also supports a non-hazardous assessment: when the engineer determines that no hazardous zone exists, the relevant Figure F.1 / F.4 exit path can be selected with one of three reasons:

• No flammable substance — F.1 first exit.
• No sources of release — F.1 second exit.
• Source eliminated — F.1 elimination exit (Continuous / Primary grade) or F.4 elimination branch (Secondary grade).

3.2 Zone classification (Table D.1)

All 21 combinations of grade × dilution × availability are implemented directly from Table D.1. For Low dilution the availability parameter is not consulted (Table D.1 footnote: the result is the same regardless). Possible outcomes:

• Zone 0 / Zone 1 / Zone 2
• Combined zones — e.g. "Zone 0 + Zone 2" or "Zone 1 + Zone 2" (two zones with different extents)
• Non-hazardous (Zone X NE) — the inner zone has negligible extent; a zone of the next tier may or may not exist (e.g. "Zone 2 (Zone 1 NE)" = Zone 2 present, but Zone 1 NE)
• Non-hazardous (Zone X NE) — fully — no zone of any type (e.g. "Non-hazardous (Zone 2 NE)")

3.3 Flowchart report

Each release source generates a PNG flowchart image showing the decision path taken through Figures F.1–F.4. The image shows only the taken path — alternative branches are omitted. The flowchart is suitable for inserting directly into a documentation annex or explosion-protection document without further editing.

The image has an adaptive header block:

• If a company logo has been uploaded for the project, it appears in the left portion of the header alongside the project name, source name, standard reference and date.
• If no logo is present, the header is compact text-only — no placeholder gap is shown.

Logos are stored per project (a consultant can use different client logos for different projects). A ZIP download bundles all source charts for a project in one click.

4. 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.

4.1 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.

4.2 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.

4.3 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.

4.4 Site Engineering — operating checklist

On the Site Engineering surface, the same three calculators above are reused unchanged. A full operating checklist — personnel safety, inert gas supply, monitoring set-points, gas-analyser inspection and calibration, fault handling and emergency measures, commissioning verification, and documentation — is drawn from a complete reading of CEN/TR 15281:2022, and is downloadable as a formatted document independent of running a check. Every item cites the clause, table or annex it is drawn from. The standard's fourth inerting method, displacement/tank-blanketing inerting (Annex C), has no dedicated calculator on either surface, but its checklist-relevant guidance (tank tightness, dedicated pressure regulators, minimum pressure-setting differences) is included in the checklist regardless.

5. 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.

5.1 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.

5.2 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.

5.3 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.

5.4 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.

6. 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.

6.1 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}.

6.2 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.

6.3 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.

6.4 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.

6.5 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.

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

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

7.1 Liquid / solvent-based paints (Annex C.2)

For each solvent substance in the paint, the module checks whether the ventilation is sufficient to keep the maximum steady-state concentration within the compliance ceiling set by §4.9.2.1. The concentration formula is:

EN 16985:2018 Annex C.2's own formula (eq. C.2) has three factors ahead of the throughput:

C = k₁ · k₂ · k₃ · Ṁ / Q   [g/m³]

where Ṁ is the substance throughput [g/s] (converted from the entered kg/h), k₁ is the mass fraction of flammable solvent in the coating material, k₂ is the estimated fraction of the substance evaporated into the booth air (default 1.0 = 100 %, a deliberately conservative choice — the standard's own worked example uses 0.80 for "common spray application"), k₃ is a turbulence/inhomogeneity factor (default 3), and Q is the supplied ventilation flow. HACacare does not ask for k₁ as a separate input: each substance's own throughput is entered directly (conservatively, the full booth throughput per substance — see below), so k₁ is implicitly 1 and only k₂/k₃ appear in the form.

Compliance ceiling (§4.9.2.1) — a hard limit by booth type, not a configurable safety margin:

• Manual booth: C ≤ 25 % LEL
• Automatic booth: C ≤ 50 % LEL

Above the applicable ceiling the standard does not describe a zone at all — the installation is simply non-compliant; ventilation must be increased or throughput reduced. Below the ceiling, the interior zone follows the concentration itself, not the booth type (Annex B's worked examples):

• Zone 2 only — C ≤ 25 % LEL
• Zone 1 + Zone 2 — 25 % LEL < C ≤ ceiling (only reachable for automatic booths, since manual booths are already non-compliant above 25 %)

The site engineer or classification engineer enters the interior zone the booth manufacturer declared; the module computes the zone the actual, measured throughput and ventilation would produce, and reports whether the two still agree — a consistency check against the manufacturer's own classification, never an independent (re-)classification.

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

7.2 Powder coatings (Annex C.3)

The powder concentration formula has no turbulence factor — a direct mass balance of throughput over airflow:

C = Ṁ / Q   [g/m³]

The compliance ceiling per §4.9.3.1 is a flat 50 % LEL, with no manual/automatic split. While compliant, the spray booth's own interior is always Zone 22 (Table 4 requires only category 3D equipment for the booth's interior across the full 0–50 % range, and 3D is defined as designed for Zone 22). Zone 21, which appears in the standard's worked figures, belongs to the separate powder recovery/filter system's powder-laden air — this module does not model that equipment, so there is no manufacturer-declared-zone comparison for Powder (the booth interior has exactly one possible outcome while compliant).

7.3 Water-based paints with co-solvent (Annex C.2, reused)

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 §7.1 check — including the same booth-type compliance ceiling and interior-zone verification — against the co-solvent's LEL. EN 16985:2018 has no separate formula for water-based paint; its informative Annex E only classifies water-based paint's ignitability, unrelated to the concentration calculation.

Ṁ_eff = Ṁ_total · f_solvent

7.4 Purge time (Annex I)

After painting stops, the booth must be purged until the concentration of a hazardous substance (e.g. an isocyanate or other toxic ingredient in the coating material — not necessarily the flammable solvent) falls to a safe, health-based occupational exposure limit. This is a distinct, health-exposure calculation from the flammability checks in §7.1–7.3, per clause 3.1.8 and Annex I:

C(t0) = M_max,Liquid · k₃ · k₄ · k₅ / Q_op                              (I.1)
t_p    = 3600 · (k₃·V / Q_op) · ln( M_max,Liquid·k₃·k₄·k₅ / (Q_op·C_LV) )   (I.4)

where V is the booth volume, Q_op is the operational airflow, M_max,Liquid is the maximum coating material throughput, k₄ is the mass % of hazardous substance in the coating material, k₅ is the estimated % emitted into the booth, and C_LV is the exposure limit value of the hazardous substance (from its Safety Data Sheet or an occupational exposure limit register — not looked up automatically). If the concentration at spray-stop is already at or below C_LV, no purge time is required. If the computed time exceeds 30 minutes, the result carries a warning to consider increasing ventilation.

7.5 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.

8. 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:

8.1 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.

8.2 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).

8.3 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).

8.4 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.

8.5 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).

8.6 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).

8.7 Site Engineering — sizing check and operating checklist

On the Site Engineering surface, the same Chamber Method A and Continuous Flow calculators are reused in assessment mode only — given an existing dryer's measured exhaust flow and its actual solvent load or throughput, the check verifies whether the resulting concentration stays within a target operating range, using the same formulas described above. The design modes (compute the required exhaust flow, or the maximum admissible load/throughput) remain HAC-Engineering-only, since this view is for checking an installation that already exists, not designing a new one. Type B (inertised) dryers, and chamber Method B (which the standard itself gives no calculation method for, §8.6), are out of scope here as well.

A full operating checklist — installation and housing, safe operation, maintenance and electrical safety, concentration monitoring, labelling and documentation — is drawn from a complete reading of EN 1539:2015's own "Information for use" clause (§7) and Annex C.1, and is downloadable as a formatted document independent of running a check. Unlike the professional surface, this view is stateless: no project is created and nothing is saved, matching the Spray Booth module's Site Engineering view.

9. Natural Gas HAC (IGEM/SR/25 Edition 2 · 2013)

The IGEM/SR/25 module classifies outdoor natural gas installations into hazardous zones. For standard source types (pipe joints, valve connections, regulators) the zone type and distance X are read directly from Table 1 or Table 2 by operating pressure and site conditions — no release-rate calculation is required. For vent pipe terminations the module follows Appendix 9 (Figs 13–16, Tables 17–27) using the orifice mass flow rate G and pipe diameter d.

9.1 Zone classification — Table 1 and Table 2

Two tables are provided depending on how freely the area is ventilated:

Within each table, the zone type and distance X are determined by:

• Operating pressure (OP) in bar g — divided into OP bands covering 0 to > 75 bar g.
• Conditions — Normal (weather-tight equipment, well-maintained joints) or Adverse (below-ground pipework, submerged fittings, inaccessible or heavily corroded equipment).
• Grade of release — the source type determines the grade: pipe joints, flanges and valve glands are secondary grade (Zone 2 or NE); valve end connections have an additional Zone 1 sphere (Xs); regulators with vent / breather pipes may produce a continuous grade release at the vent outlet (Xb).

Vent pipe terminations do not use Table 1 or Table 2; their zones are determined by Appendix 9 (see §9.5).

9.2 Xs — Zone 1 sphere (clause 5.2.3)

Clause 5.2.3 requires a Zone 1 sphere of radius Xs around the release point for both valve end connections and vent pipe terminations. The radius depends on the operating pressure:

For valve connections the outer Zone 2 distance X from the table still applies beyond Xs. For vent pipe terminations Xs is the Zone 1 sphere around the pipe outlet; all other Appendix 9 distances (Xc, Xh, Xp, X1, Xn, X) are Zone 2.

9.3 Xb — vent pipe dispersion radius (regulators, Table 18)

Regulators fitted with a breather or atmospheric vent pipe can release gas continuously. IGEM/SR/25 Table 18 gives the dispersion radius Xb (metres) from the vent outlet as a function of the mass release rate G [kg/s]. The module calculates G from the operating pressure P, orifice area (from internal diameter d), discharge coefficient C_d (default 0.8), gas temperature T and molar mass M using the standard's orifice formula:

G = Cd · A · P · √( γ · M / (R · T) · (2 / (γ+1))(γ+1)/(γ-1) )   [kg/s]

The zone within Xb carries the same grade (and therefore the same zone type) as the main X distance. If G exceeds the Table 18 maximum (0.002 kg/s), the module reports "above range" and recommends a more detailed dispersion model.

9.4 Project storage and XLSX report

The IGEM/SR/25 module is project-backed: multiple release sources are collected under a named project (plant and area metadata supported). Each source is individually classified; the project page shows all results in a summary table with coloured zone badges.

An XLSX report can be downloaded at any time. When the project contains both standard sources and vent pipe terminations, the report has two sheets:

• HAC Results — standard source types (pipe joints, valve connections, regulators) with Table 1 / Table 2 results and embedded Figure 1 source-type reference images.
• Vent Pipe (App. 9) — vent pipe termination results with dynamic columns (only distance variables that have values are shown) and individual Appendix 9 figures (Figs 13–16) for each subtype present, with the corresponding source tags displayed above each figure.

Projects can be shared with other HACacare users (see §11).

9.5 Vent pipe terminations (Appendix 9, Figs 13–16)

Vent pipe terminations are classified using the procedure of IGEM/SR/25 Edition 2 Appendix 9. The Xs sphere (Zone 1) is set by operating pressure per clause 5.2.3 (see §9.2). The outer zone distances (Zone 2) are read from Appendix 9 tables by G [kg/s] and d [mm]. Four subtypes are supported, each corresponding to a different figure and set of tables:

Mass flow rate G — either entered directly or calculated from the pipe internal diameter d using the sonic orifice formula (clause 5.2.2.2). For vent pipe orifices the discharge coefficient is C_d = 1.0 and the effective pressure used in the formula is OP × 1.10 (110 % of the operating pressure), both per clause 5.2.2.2. When G is calculated from an orifice, the formula details (d, OP, T, M, C_d, computed G) are recorded in the Notes column of the XLSX report for audit traceability.

Grade of release is fixed at primary for vent pipe terminations (the vent outlet is a primary release point). The standard site conditions / location inputs (Table 1 vs. Table 2) are not applicable and are not requested in the form.

10. Electrostatic Hazards Evaluation (IEC/TS 60079-32-1:2013+A1:2017)

IEC/TS 60079-32-1 is a guidance technical report on electrostatic hazards — 184 pages, mostly procedural/checklist guidance across 14 clauses. HACacare currently implements one part of it: Annex F, Figure F.1, "Flowchart for a systematic electrostatic evaluation" — a qualitative screening tool with no release-rate or ventilation calculation, in the same spirit as the Qualitative HAC module (§3) but for a different standard and a different flowchart. Later phases of the standard (a tank filling-velocity calculator, an earthing/bonding adequacy check, a broader operating checklist) are not yet in scope.

10.1 The flowchart

The tool first asks whether electrostatic charging is expected at all — from separation processes (e.g. manual rubbing), charged particles (e.g. near HV electrodes), or induction from nearby charged objects. If not, the only outcome is the standard's own residual precaution: clean the item with a wet cloth only and allow it to dry naturally.

If charging is expected, Figure F.1 forks into two paths — labelled "1st" and "2nd" on the diagram itself — which are alternatives, not a simultaneous evaluation: you choose whichever matches the material you are assessing, and if an item has both kinds of material, you run the tool twice.

Every question is quoted verbatim from the standard's own flowchart boxes, and each one has an expandable "what does this mean?" panel with a plain-language explanation. Where a question references a table specifically (maximum isolated capacitance, maximum insulating-surface size, maximum acceptable transferred charge), the actual table is shown — not a paraphrase of its numbers.

10.2 Report and availability

The result shows the full decision trail (every question answered, with its explanation) and is downloadable as an editable block-diagram report (PPTX) — a redrawn version of the evaluated path, colour-coded by hazard severity, with a reference appendix covering every clause and table actually used. This module is stateless (no project, nothing saved server-side) and, unlike every other module above, has no separate reduced view — the identical page is linked from both HAC Engineering and Site Engineering (see §1.1).

11. 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. Searching, viewing and selecting a substance for a calculation is available to every signed-in user; editing or deleting an entry in the shared database (the Substances admin page) is restricted to administrators, since a change there affects every user of the installation.

12. 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.

12.1 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 self-service hard delete; a data-removal or data-export request is handled by an administrator on request, through a documented process.
• Login history is kept for 12 months and then automatically deleted.

12.2 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 §11.4).

12.3 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.

12.4 Sharing (co-working)

Sharing is available in all project-backed modules (Gas & Vapour, Qualitative HAC, 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).

12.5 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. The Electrostatic Hazards Evaluation module (§10) is also stateless in this sense, but goes one step further: it has no separate Site Engineering blueprint at all, unlike every other module named here.

By contrast, the Gas & Vapour, Qualitative HAC, 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.

12.6 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.

A separate emergency access page lets an admin grant a named colleague access to someone else's project in the Spray Booth, Dryer, Qualitative HAC and IGEM/SR/25 modules — for example when a project owner is on leave and did not share the project themselves before leaving. This bypasses the normal owner-only sharing requirement (§12.4), so every grant is recorded in an admin action log for accountability.

13. 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.

14. 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.

15. 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.
• IEC/TS 60079-32-1:2013+A1:2017 — Explosive atmospheres — Part 32-1: Electrostatic hazards, guidance. Consulted via its Hungarian endorsement, MSZ CLC/TR 60079-32-1:2019. Primary procedural reference for the electrostatic hazards module (Annex F, Figure F.1, Tables 1–4).
• 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.

16. Disclaimer