4way gas monitors

4-way gas monitors are used to detect hazardous atmospheric conditions including:

• Oxygen (O2) level in percent (%)
• Flammable or explosive atmospheres in percent lower explosive limit (% LEL)
• Toxic materials Carbon Monoxide (CO) and Hydrogen Sulfide (H2S) in parts per million (ppm) [1]

These monitors cannot measure all atmospheric hazards, as some toxic chemicals require a specific sensor to measure them. Examples of hazards needing specific sensors include ammonia and chlorine. [1] [2]

ISEA recommends conducting a bump test or calibration check of portable gas monitors before each day's use, according to the manufacturer's instructions. If a portable gas monitor fails a bump test or a calibration check, you must fully calibrate the monitor before further use, or remove it from service. [4]

When welding, burning, or other spark producing operations are taking place, the atmosphere must contain less than 20% of the LEL of gases or vapors. Testing for gases or vapors must be done before and continuously during work. [3]