Calculator Inputs
Example Data Table
| Scenario | Room (m) | Volume (m³) | Agent | Conc. (%) | Temp (°C) | Pressure (kPa) | Est. mass (kg) |
|---|---|---|---|---|---|---|---|
| Small server room | 5 × 4 × 3 | 60 | Novec 1230 | 5.3 | 20 | 101.325 | ~88 |
| Electrical switchgear | 8 × 6 × 3 | 144 | FM-200 | 7.0 | 20 | 101.325 | ~245 |
| Archive storage | 10 × 8 × 3 | 240 | Inergen | 35.0 | 20 | 101.325 | ~447 |
Examples are illustrative screening values, not final design quantities.
Formula Used
This calculator uses an ideal-gas screening model at enclosure conditions:
- n_total = (P × V) / (R × T)
- n_agent = x × n_total, where x = concentration / 100
- m_base(kg) = n_agent × MW / 1000
- m_final = m_base × vent_factor × (1 + safety/100)
- cylinders = ceil(m_final / cylinder_capacity)
Symbols: P (Pa), V (m³), T (K), R (8.314462618 J/mol·K), MW (g/mol). The venting factor and safety margin provide practical allowances.
How to Use This Calculator
- Select the clean agent type used for your system.
- Enter design concentration from your hazard requirements.
- Choose dimensions or direct volume, then fill values.
- Set temperature and pressure matching enclosure conditions.
- Apply a venting factor to cover leakage and discharge effects.
- Add a safety margin and cylinder capacity for packaging.
- Press Submit to view results above the form.
- Use Download CSV or PDF for your records.
Design Inputs and Assumptions
This calculator estimates the required clean agent mass for a total flooding discharge using an ideal‑gas screening model. Inputs include enclosure volume, design concentration, ambient temperature, and pressure. The model treats the target concentration as an approximate mole fraction and assumes uniform mixing at the specified conditions, producing a fast, transparent first‑pass estimate for sizing and peer review.
Interpreting Concentration and Mole Fraction
Design concentration is entered as a percent. Internally, the tool converts it to x = C/100 and applies it to total moles in the room, n_total = P·V/(R·T). Agent moles are then n_agent = x·n_total. Molecular weight converts moles to kilograms, so selecting the correct agent materially affects results. This approach supports reporting in moles, kmol, kg, and kg per cubic meter.
Temperature and Pressure Sensitivity
Gas density varies with temperature and pressure, so the same volume can require different agent mass across sites and seasons. At higher temperatures, T increases and n_total decreases, reducing the computed mass. At higher pressures, n_total increases, raising the mass. For example, moving from 90 kPa to 101.3 kPa increases total moles by about 12.6%, holding other inputs constant. A 10°C rise from 20°C to 30°C reduces n_total by roughly 3.3%.
Venting and Safety Allowances
Real enclosures leak and discharge dynamics are imperfect. The venting factor scales the base mass to cover losses from openings, door gaps, and pressure relief behavior. A separate safety margin adds additional allowance for uncertainty and project conservatism. Together they produce m_final = m_base·vent_factor·(1 + safety/100), which is easier to audit than hidden heuristics and helps align estimates with field testing outcomes.
Packaging and Documentation Outputs
The tool converts the adjusted mass into an estimated cylinder count using ceil(m_final/cylinder_capacity). This supports early layout planning, budgetary quotes, and logistics checks. Mass per cubic meter helps compare scenarios and agents on a normalized basis. After calculation, results appear above the form for quick review, and exports provide a consistent CSV and PDF record for engineering files, reviews, and handover packages.
FAQs
1) Is this calculator suitable for final system design?
Use it for early sizing and checks. Final design should follow applicable standards, manufacturer flow data, nozzle coverage, and enclosure integrity testing to confirm concentration and hold time.
2) What does venting factor represent?
It scales the base mass to account for leakage, discharge losses, and imperfect mixing. Higher values add conservatism when openings, pressure relief behavior, or enclosure sealing quality are uncertain.
3) Why include temperature and pressure?
Gas density depends on both. Higher pressure increases required moles and mass, while higher temperature decreases them. Using site conditions improves consistency when comparing different elevations and seasonal operating ranges.
4) How should I choose design concentration?
Use the value required for the hazard class and agent, including safety limits for occupancy where applicable. Many projects use manufacturer guidance or standard tables, then verify with acceptance testing.
5) Why do different agents give different masses?
Agents have different molecular weights. For the same target mole fraction, a higher molecular weight produces a higher mass. The calculator applies molecular weight directly when converting moles to kilograms.
6) What do the CSV and PDF exports include?
They capture inputs, intermediate values, adjusted mass, mass per cubic meter, and estimated cylinder count. Exports help with reviews, quoting, and traceable project documentation.