Confined Space Gas Test Check
Enter the worst reading from your top, middle and bottom tests. Set the limits to your site procedure; the defaults are commonly used alarm settings, shown as examples only.
| Gas | Reading | Entry limit |
|---|---|---|
| Oxygen (O₂, %) | – | |
| Flammable (% LEL) | max | |
| Hydrogen sulfide (H₂S, ppm) | max | |
| Carbon monoxide (CO, ppm) | max |
A passing test is one condition for entry, not permission on its own. Entry also needs a valid permit, trained entrants, a trained attendant outside, continuous monitoring and a rescue plan. Other toxic gases may need their own sensors depending on the space and the work.
Frequently asked questions
What does a four-gas detector measure?
Most portable detectors used for confined space entry measure oxygen, flammable gas as a percentage of the lower explosive limit (LEL), hydrogen sulfide and carbon monoxide. Other toxic gases may be present depending on the space and the work, and need their own sensors.
What limits should I use?
Use the entry limits set by your site procedure and the law where you work. The defaults in this tool are commonly used alarm settings shown as examples only. Many organisations use stricter limits for entry than for alarms.
Is one good reading enough?
No. Test before entry at the top, middle and bottom of the space, because gases separate by density. Keep monitoring continuously while people are inside, because conditions can change quickly.
Who can enter after a pass?
Only trained people, under a valid entry permit, with a trained attendant outside and a rescue plan in place. A passing gas test is one condition for entry, not permission on its own.