In what order should a confined space be tested for hazards?

The correct order for testing a confined space for hazards is to first measure the oxygen levels, followed by checking for flammable gases or vapors, and finally assessing for toxic air.

Starting with oxygen is crucial because a deficiency or excess of oxygen can pose immediate life-threatening conditions. If the oxygen level is not within a safe range (between 19.5% and 23.5%), entering the space could be dangerous, regardless of the presence of flammable or toxic substances.

After verifying that the oxygen levels are safe, the next step is to test for flammable gases and vapors. Ensuring that the atmosphere is not flammable helps prevent explosions or fires before any further testing for toxic air is conducted.

Finally, testing for toxic air is vital as well; these gases may not present an immediate physical threat like low oxygen or high flammability, but they can still be harmful over time or in certain concentrations. By following this order, the greatest physical threats to safety are addressed first, mitigating potential risks effectively before advancing to check for other hazardous conditions.

This systematic approach aligns with best practices in confined space entry safety, ensuring comprehensive hazard recognition and mitigation.