Authorized Gas Tester (AGT)


The atmosphere shall be tested by an Authorized Gas Tester initially and continuous monitoring may be done by an Authorized Gas Tester or an authorized entrant. The continuous monitoring of atmospheric condition shall be carried out consistent with the hazards identified and the risk assessment.


Who is Authorized Gas Tester?

  1. A person who appointed by employer to carry out atmosphere test for confined space.
  2. Had attended a training course on safe working in confined space for Authorized Gas Tester and Entry Supervisor and
  3. Passed the test or examination of Authorized Gas Tester




Each Authorized Gas Tester shall:

  1. Update his knowledge on the hazards that may be faced during entry, including information on the mode, signs and symptoms, and consequences of the exposure
  2. Identify all chemical hazards and recommends control measures to ensure safe entry
  3. Be familiar with all confined space entry equipment used, for example emergency breathing apparatus, man riding winch, tripod, etc.




  1. The atmosphere must be tested by an Authorized Gas Tester initially in pre-entry stage.
  2. Continuous monitoring may be done by an Authorized Gas Tester or an authorized entrant.
  3. The continuous monitoring of atmospheric condition shall be carried out consistent with the hazards identified and the risk assessment.




Additional Recommendation For Atmospheric Testing

Factors to be taken into account include the following:-

  1. Properties of the gas / vapor
  2. Humidity and temperature in the space
  3. Presence of airborne contaminants that may reduce the accuracy of the reading or (poison) the sensor
  4. Presence of corrosive gases and mists, which may damage the sensor and give misleading results causing a false zero reading
  5. Calibration, adjustment and maintenance requirements
  6. Need for re-calibration during testing
  7. Condensation and/or absorption of gas into the walls of sampling lines where these are used
  8. Response of the instrument to high and low concentrations of flammable gas or vapors (for example, false zeros)
  9. Oxygen deficiency causing a false flammable gas reading
  10. Oxygen enrichment where the instrument may act as an ignition source causing an explosion
  11. Differences in atmospheric pressure which may cause erroneous readings in some sensors



Equipment for monitoring of flammable gases, dusts and vapors should be intrinsically safe. All electronic equipment for monitoring should be equipped with an audible or visual alarm. Instruments used for testing the atmosphere in a confined space should be selected for their functional ability to measure hazardous concentrations.

After air purging has been completed, forced air ventilation devices, such as inductors or fans should be turned off for a sufficient time to allow for a normal atmospheric condition to exist for the gas testing of the confined space. If an acceptable result cannot be obtained without continuous forced air ventilation, then the forced air ventilation device should be suitably tagged and / or locked to ensure it is not disconnected while the inspection or other work is in progress. The stand-by person is responsible for monitoring the proper operation of the forced air ventilation device.

Testing of the confined space shall be carried out before the entry permit to work is issued. The tests shall be check on the presence of gas or fumes, on chemical deposits, and, where appropriate, on the adequacy of the supply of oxygen. A satisfactory result shall be obtained before proceeding further.

References: Industry Code of Practice for Safe Working In A Confined Space 2010 (ICOP 2010), Department of Occupational Safety and Health, Ministry of Human Resources, Malaysia


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