Quick answer
An Authorized Gas Tester (AGT) is a person registered with DOSH who is competent to test the atmosphere of a confined space before entry and to monitor it during work, under DOSH's Industry Code of Practice for Safe Working in a Confined Space (2010). The ICOP requires pre-entry gas testing to be performed by a DOSH-registered AGT, who advises on atmospheric hazards and entry conditions. A fixed gas detection system provides continuous monitoring and complements the AGT's role, but it does not replace the AGT's pre-entry testing and entry-permit responsibilities. For the regulatory background, see the DOSH gas detection compliance guide.
The AGT role in one paragraph
The AGT is the competent person at the center of the confined-space gas testing regime. Before anyone enters a tank, pit, silo, duct, or vessel that qualifies as a confined space, the AGT tests the atmosphere for oxygen adequacy and for flammable and toxic gases, recording results for the entry permit. During the work, the atmosphere is monitored continuously so changing conditions are caught early, and the AGT advises the entry supervisor whether the space is safe to enter or remain in.
Why DOSH registration matters
Registration is the difference between a trained individual and a recognized one. It creates a verifiable record that the tester met the required standard for a task where an error can be fatal, and it disciplines the process: registered testers work to the code of practice, use calibrated instruments, and document results in the entry-permit system. Read the DOSH requirements overview for how the AGT fits into the wider duty of care under OSHA 1994.
AGT vs fixed gas detection system
The AGT and a fixed gas detection system answer different questions. The AGT performs point-in-time atmospheric testing tied to a specific entry event, makes a go or no-go judgment, and carries responsibility under the permit system. A fixed system monitors installed areas continuously and alarms automatically, including during unmanned hours when no AGT is present.
Neither substitutes for the other. A fixed system cannot complete an entry permit; an AGT cannot be present everywhere, all the time. Treat them as complementary layers: continuous electronic monitoring plus qualified human testing at the moment of entry. The testing and commissioning guide covers how monitoring equipment is verified so it can be trusted when it alarms.
How facilities coordinate both
Coordination starts with the risk assessment: identify which site spaces are confined spaces and which areas carry continuous gas hazards. Confined-space procedures name the registered AGT, define the testing sequence and acceptance criteria, and the entry-permit system, while the fixed design covers wider area risks.
The two layers meet in documentation. AGT test records, fixed-system event logs, and calibration records together form the evidence file showing that gas hazards are managed on an ongoing basis. Review the fixed gas detection system overview when planning the monitoring layer.
Official AGT resources and equipment planning
For current role descriptions, eligibility and application guidance, consult DOSH's Authorised Gas Tester / Entry Supervisor page. Use the official source for competency requirements and U-Tai's guides for equipment planning; these are separate decisions.
Read the portable gas detector guide and maintenance-record checklist when preparing equipment information. Confirm the required gases, exact model, sensor configuration, sampling method and matching manual with the responsible safety team. A single-gas instrument is not a multi-gas monitor. These resources do not establish approval for an AGT task or replace the site's entry permit or approved test procedure.