Confined Space Air Monitoring Calculator
Evaluate LEL, O2, H2S, and CO readings against OSHA action levels for permit-required confined spaces.
Inputs
Results
Entry Permitted
1
Immediate Evacuation Required
0
Total Hazards Flagged0
O2 Status (0=Low, 1=OK, 2=High)1
LEL Action Level Exceeded0
H2S Action Level Exceeded0
CO Action Level Exceeded0
How to Use This Calculator
- Enter the oxygen reading (%) from your meter.
- Enter the combustible gas reading as percent of Lower Explosive Limit (LEL %).
- Enter the hydrogen sulfide (H2S) and carbon monoxide (CO) readings in ppm.
- Check Entry Permitted and Immediate Evacuation Required to see if the atmosphere meets OSHA action levels.
- Review O2 Status and the LEL/H2S/CO action-level flags, plus Total Hazards Flagged, to identify which readings are out of range.
How the result changes with Oxygen (%)
| Oxygen (%) | Entry Permitted | Immediate Evacuation Required |
|---|---|---|
| 2.5 | 0 | 1 |
| 8.75 | 0 | 1 |
| 16 | 0 | 1 |
| 23 | 1 | 0 |
What each input means
- Oxygen (%)
- Oxygen concentration (normal is 20.9%).
- LEL (%)
- Combustible gas reading as percent of Lower Explosive Limit.
- H2S (ppm)
- Hydrogen sulfide concentration in parts per million.
- CO (ppm)
- Carbon monoxide concentration in parts per million.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersOxygen (%) = 20.9, LEL (%) = 5, H2S (ppm) = 5, CO (ppm) = 10 = 4 input(s) provided
- Calculate Entry PermittedEntry Permitted1 = 1
- Calculate Immediate Evacuation RequiredImmediate Evacuation Required0 = 0
- Calculate Total Hazards FlaggedTotal Hazards Flagged0 = 0
- Calculate O2 StatusO2 Status1 = 1
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.
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