Confined Space Gas Testing Procedure

How to Develop a Confined Space Gas Testing Strategy.

Confined Space Gas Testing

Gas Testing 101 – Confined Spaces

We frequently receive requests for the development of confined space gas testing procedures, a task that may entail a considerable investment of time, contingent upon the complexity of the anticipated work. The ensuing checklist is proffered to provide our readers with a systematic guide in crafting their individualised confined space gas testing procedures.


Confined space atmosphere testing is a critical aspect of occupational safety, ensuring individuals working within confined spaces are protected from potential hazards such as toxic gases, flammable substances, and low oxygen concentration. The following outlines a simple procedure for testing the atmosphere in confined spaces.


The primary objectives of confined space atmosphere testing are to:

  • Identify and quantify hazardous gases present in the confined space.
  • Ensure the oxygen concertation is within acceptable limits.
  • Implement appropriate safety measures based on test results.
  • Facilitate safe entry and work within confined spaces.

Preparing to Test Confined Spaces

Before initiating confined space atmosphere testing, the following preparatory steps should be taken:

Identify Confined Space and Hazards:

  • Clearly define the confined space and potential hazards associated with it.
  • Understand the physical and chemical properties of substances likely to be present.
  • Determine Testing Requirements:
  • Identify specific gases to be monitored based on the confined space and potential hazards.
  • Determine the appropriate detection limits for each gas.

Select Appropriate Gas Detection Equipment:

  • Choose gas detection instruments suitable for the identified hazards.
  • Ensure instruments comply with relevant safety standards.

Calibrate Gas Detectors:

  • Calibrate gas detectors before each use following the manufacturer’s guidelines.
  • Conduct a zero-air calibration to establish a reference point.

Check Equipment Integrity:

  • Inspect gas detectors for physical damage or malfunction.
  • Confirm batteries are fully charged, and all components are functioning correctly.

Testing Procedure

  • Ventilate the Confined Space:
  • Before testing, ventilate the confined space to ensure a safe starting atmosphere.
  • Utilise fans or blowers to enhance air circulation.

Establish Monitoring Strategies:

  • Identify strategic monitoring points within the confined space, considering potential variations in gas concentrations.
  • Determine locations at different levels (top, middle, bottom) for comprehensive monitoring.

Prevent False Readings:

  • Position the sampling probe away from potential sources of contamination, such as exhaust vents or chemical leaks.
  • Minimise interference from external factors that could affect readings.

Initial Gas Tests:

  • Conduct initial tests from outside the confined space to assess the overall atmosphere.
  • Test for oxygen levels, flammable gases, and specific hazardous gases.

Entry Procedures:

  • Equip personnel with appropriate PPE, including respiratory protection, based on the initial test results.
  • Allow entry only if the atmosphere is deemed safe for occupation.

Continuous Monitoring:

  • Continuously monitor the atmosphere during work inside the confined space.
  • Regularly test for changes in gas concentrations, adjusting safety measures as needed.

Emergency Response

Emergency Plan:

  • Develop a comprehensive emergency response plan for potential hazardous situations.
  • Ensure communication equipment is available for constant contact with personnel inside the confined space.

Evacuation Procedures:

  • Establish clear procedures for evacuating the confined space in the event of hazardous conditions.
  • Train personnel on emergency response protocols.

Post-Work Testing and Documentation

Final Tests:

  • After completing work, conduct final tests to verify that the atmosphere remains safe for exit.
  • Confirm that gas concentrations are within acceptable limits.

Record Keeping:

  • Document all test results, including gas concentrations, calibration records, and any corrective actions taken.
  • Maintain detailed records for regulatory compliance and future reference.Review and Improvement

Post-Work Review:

  • After completing confined space work, conduct a review of the monitoring process.
  • Identify any challenges or areas for improvement in the testing procedure.

Continuous Improvement:

  • Implement changes to the confined space atmosphere testing procedure based on the post-work review.
  • Periodically update procedures to align with industry best practices and regulatory requirements.


This document provides a simplified confined space atmosphere testing procedure to help you design and implement what is most suitable for your circumstances. Adhering to these guidelines, along with industry standards and regulations, is essential to mitigate risks and create a secure working environment within confined spaces. Regular training and equipment maintenance also contribute to the effectiveness of this testing procedure. If you would like to know more or attend on of our training courses related to confined space atmosphere testing please contact us.

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