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BP MIGCS study materials
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BP MIGCS: Inspection, Testing, and Commissioning

BP MIGCS · Work through your exam, one topic at a time.

All guide sections

Inspection, Testing, and Commissioning

What this domain tests

This domain tests pre-start inspection, pressure and leak testing, purging, clocking the meter, combustion analysis, safety-device checks, and documentation. You must prove the installation is safe and performs to its rating before handover.

Core rules and concepts

  • Inspect against the approved plans: clearances, venting, combustion air, piping supports, shutoff access, sediment trap, and appliance listing.
  • Confirm the pressure test was completed at the correct pressure and duration before gas is introduced.
  • Purge with the appliance isolated or to a safe outside location; never purge into a confined space.
  • Leak-test joints at operating pressure with an approved bubble solution or detector. Do not use a flame.
  • Check static and operating gas pressure at the appliance inlet with the appliance running. Low pressure causes underfiring; high pressure can overfire and produce CO.
  • Clock the meter to verify input. Formula: input (Btu/h) = test dial volume (ft³) × 3,600 ÷ time (seconds) × heating value (Btu/ft³).
  • Perform combustion analysis and draft or spillage testing. Verify flame roll-out, high-limit, pressure switch, and other safety devices operate.
  • Record as-found and final readings, model and serial numbers, clearances, and any derating.

Worked example

A furnace rated 100,000 Btu/h is clocked on a 2 ft³ meter dial. The dial completes one revolution in 72 seconds. Input = 2 × 3,600 ÷ 72 × 1,000 = 100,000 Btu/h. If the same dial takes 90 seconds, input = 2 × 3,600 ÷ 90 × 1,000 = 80,000 Btu/h, which is underfired. Reasoning: check manifold pressure, orifice size, and supply pressure before adjusting; confirm no other appliances are running during the test. After correction, repeat the clocking and combustion analysis.

Traps that cost marks

  • Clocking the meter while other appliances operate.
  • Using the wrong dial volume or ignoring the meter multiplier.
  • Checking pressure only with the appliance off.
  • Skipping safety-device tests because the appliance fires normally.
  • Failing to record combustion and draft results.
  • Leaving the job without labeling shutoffs and providing operating instructions.

Exam tactic

For commissioning questions, follow the sequence: inspect, pressure/leak test, purge, start, clock, analyse combustion, test safeties, document.