On-Site Atmospheric Testing and Monitoring Technician

Atmospheric testing is a safety procedure that assesses the air quality of a space, most commonly a confined space, before entry to ensure it is safe for workers. The process involves a two-part testing approach: initial evaluation testing to identify potential hazards, followed by verification testing to confirm safe conditions exist. Essential tests include measuring oxygen levels, detecting flammable gases (below 10% of the Lower Explosive Limit), and monitoring for toxic gases like carbon monoxide and hydrogen sulfide. Testing must be performed in a specific order (oxygen, then combustible, then toxic gases) and at various points within the space (top, middle, and bottom) to account for gas layering. 

Evaluation testing 

• This is an initial assessment to identify and evaluate potential hazards in a space.
• It should be performed by a technically qualified professional.
• The results of this testing inform the steps needed for safe entry, which are documented on a permit. 

Verification testing 

• This is a pre-entry test to ensure the atmosphere is safe for entry.
• It verifies that the hazards identified during evaluation testing are below acceptable limits.
• Testing is performed immediately before entry, within 15 minutes. 

Testing order and methodology 

• Order: Test the atmosphere in this sequence: 1) oxygen, 2) combustible gases, and 3) toxic gases.
• Levels: Sample the air at the top, middle, and bottom of the space because some gases are lighter or heavier than air.
• Sampling: Use a pumped detector with a sampling hose to get samples from a distance away from the entry point to avoid false readings from outside air.
• Continuous monitoring: Continuous monitoring is a best practice and is required if ventilation is used to control hazardous conditions.
• Calibration: Use calibrated equipment and ensure it passes a bump test before use. 

Key atmospheric parameters to monitor 

• Oxygen: Must be between 19.5% and 23.5% for safe entry.
• Flammable gases: Must be below 10% of the Lower Explosive Limit (LEL).
• Toxic gases: Common examples include carbon monoxide (CO) and hydrogen sulfide (H2S), which must be monitored to ensure they are below permissible exposure limits. 

Accurate Safety Compliance utilizes both fixed and portable gas detection systems dependent on the situation as well as colormetric tubes for headspace testing and lead acetate strips for fluid sampling.