5Gas Unit Converter
Convert between ppm ↔ %LEL ↔ mg/m³ ↔ %Volume for the most common industrial gases. Conversion uses the molar volume at the selected T & P; defaults are 25 °C and 101.325 kPa per NIOSH.
Converted values
ppm—
% LEL—
mg/m³—
% Volume—
6SCBA Duration Calculator
Service life ≈ [(Pᶜʸˡ − Pʳᵉˢ) × Vᶜʸˡ / Pₐₜₘ] / RMV, with breathing rate scaled by work intensity. Output includes the recommended one-third safety reserve for escape (NFPA 1404).
Air available
Free air in cylinder—
Usable air (above reserve)—
Working duration
— min total
— min safe (after reserve)
—
—
7Confined Space Ventilation Calculator
Compute the airflow required to achieve the target air-changes-per-hour (ACH) for a confined space: Q = (V × ACH) / 60 in CFM, also expressed in m³/h.
Required airflow
Volume—
Required Q—
Required Q—
Recommendation—
—
20TWA / STEL Exposure Calculator
Add up to 6 exposure intervals during a shift, then the tool computes the 8-hour Time-Weighted Average and compares against the OEL/STEL for the selected gas. Formula: TWA₈ = Σ(Cᵢ·tᵢ) / 8 h.
Exposure intervals
| Activity | Conc (ppm) | Duration (min) |
|---|
Exposure summary
— ppm · 8-h TWA
—
Total weighted exposure (ppm·h)—
Total exposed time—
Peak short-term concentration—
vs TWA limit—
vs STEL (15-min limit)—
—
For training purposes only. Defer to NIOSH, OSHA 1910.146, NFPA and the gas-detector manufacturer's calibration data for actual entry decisions.