A 4-gas monitor, sometimes called a 4 gas meter or a multi gas detector, measures carbon monoxide (CO), oxygen (O2), hydrogen sulfide (H2S), and combustible (EX-LEL) gases. Used for confined spaces such as tanks, vessels, silos, and tunnels. Maritime, oil and gas, construction, mining, water, and wastewater are just some of the industries that make use of 4 gas monitors. Please determine if you require a 4 gas monitor with or without a pump. See our YouTube Playlist of our 4 Gas Monitors.