Detection of Hazardous Gases by Confined‑Space Detectors
For hazardous‑gas detection in confined spaces, the detector must perform pre‑entry testing. Hazardous‑gas components inside the confined space shall be remotely measured before personnel enter. Testing shall be carried out in the following sequence: (1) Oxygen verification: measure the current oxygen concentration level; (2) Flammable‑gas verification: monitor variations in flammable‑gas levels; (3) Toxic‑gas verification: confirm that the concentration of each toxic gas is below the Permissible Exposure Limit (PEL) specified by OSHA. Common toxic gases found in confined spaces include hydrogen sulfide and carbon monoxide, excluding other toxic compounds. Detectors manufactured by RAE can measure either single gases or mixed toxic‑gas species simultaneously.
It is critical to sample and measure gas or vapour concentrations at the top, middle and bottom of a confined space. Some gases are lighter than air (such as methane and other flammable gases) and tend to accumulate in the upper section of confined spaces. Gases heavier than air (such as hydrogen sulfide) gather at the bottom. Other gases with density close to that of air (such as carbon monoxide) concentrate in the middle zone.
Take samples at different heights within the confined space and run continuous measurements with the detector according to site‑specific conditions; different readings will be obtained.
As a remote air‑monitoring unit deployed in hazard zones, the detector provides continuous measurement data to support safe entry into restricted areas. The probe or viewing port of a confined‑space entry detector constantly transmits measurement results to personnel outside. Conditions inside a confined space are dynamic and may change due to leaks, release of toxic vapours or environmental shifts, even without an alarm being triggered.
Detectors for confined‑space entry RAE has recently launched an innovative Confined‑Space Entry (CSE) detector that incorporates all functions of a multi‑gas detector. Named the Q‑RAE Confined‑Space Entry Detector, this instrument features multiple convenient preset tools for gas testing required under OSHA 29 CFR 1910.146. These presets enable more‑efficient measurements for flammable gases, hydrogen sulfide, carbon monoxide and varying oxygen concentrations.
