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Gas detection and entryLesson 3 of 6

Bump tests, calibration and calibration certificates

You will be able to tell a bump test from a calibration, run both correctly, and check a gas detector's certificate and log the way a port state inspector would.

15 minutes · For signed-up learners, free · Rules checked 20 October 2026

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A gas detector drifts. Sensors age, get poisoned by silicone sprays or exhaust, dry out in heat or get wet. The display still shows a confident number. The only ways to know whether that number is true are to expose the sensors to a gas of known strength (a bump test or calibration check), and to adjust them when they are off (a calibration).

SOLAS has required “suitable means” for calibrating every ship’s portable atmosphere testing instrument since 1 July 2016, and the IMO has had to explain twice (once for this meter, once for the tanker instruments of SOLAS II-2/4.5.7.1) that a quick test with span gas before use is not what the rule means. Calibration is also where port state inspectors look first: an out-of-date certificate is easy to spot, and the Marshall Islands Administrator has warned owners about a rise in US Coast Guard deficiencies for poorly calibrated instruments.9

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The rest of this lesson, the interactive Gas detection locker check before a port state inspection and the quiz are open to signed-up learners. It's free, takes a minute, and opens every lesson in all 14 courses.

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In this lesson

  • Try it: Gas detection locker check before a port state inspection
  • In plain words
  • In detail
  • What the rules say
  • Flag and class notes
  • Key numbers
  • What inspectors find
  • Questions people ask
  • Quiz: 6 questions

Sources

  1. 1 IMO Resolution MSC.380(94), Amendments to SOLAS (adopted 21 November 2014, in force 1 July 2016), Annex, regulation XI-1/7. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.380(94).pdf
  2. 2 IMO MSC.1/Circ.1561, Unified interpretation of SOLAS regulation XI-1/7 (28 November 2016), Annex. Copy published by the Finnish Transport and Communications Agency (Traficom): https://www.traficom.fi/files/media/regulation/24358-MSC_1-Circ_1561_-_SOLAS_X-I-17_Calibration_of_portable_atmosphere_testing_instruments_.pdf
  3. 3 IMO Resolution MSC.350(92), Amendments to SOLAS (adopted 21 June 2013, in force 1 January 2015), Annex, regulation III/19 paragraphs 3.3 and 3.6. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.350(92).pdf
  4. 4 IMO Resolution MSC.581(110), Revised recommendations for entering enclosed spaces aboard ships (adopted 27 June 2025), Annex, sections 3.6, 6.5.3, 7.2 and 8.2. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.581(110).pdf
  5. 5 Indian Register of Shipping, Technical Circular 011/2017, The Bahamas National Requirements, Revision 08 (17 January 2017): atmosphere testing instruments, calibration. https://www.irclass.org/media/2668/technical-circular-no-11.pdf
  6. 6 IMO MSC.1/Circ.1581, Unified interpretations of SOLAS chapter II-2 (16 June 2017), Annex, regulation 4.5.7.1. Copy published by Traficom: https://www.traficom.fi/files/media/regulation/28723-MSC_1-Circ_1581_-_UI_Gas_measurement%2C_Tankers_SOLAS_Ch_II-2_.pdf
  7. 7 MSA Safety, What’s the difference between a bump test and calibration (summary of the ISEA Statement on validation of operation for direct reading portable gas monitors, March 2010). Industry practice, not an IMO requirement. https://blog.msasafety.com/whats-the-difference-between-a-bump-test-and-calibration-and-why-should-you-care/
  8. 8 IMO MSC.1/Circ.1477, Guidelines to facilitate the selection of portable atmosphere testing instruments for enclosed spaces (9 June 2014), Annex paragraphs 9, 16 and 17. Copy published by the Vietnam Maritime Administration: https://vimawa.gov.vn/f/circ%201477.PDF
  9. 9 Republic of the Marshall Islands Maritime Administrator advisory on improperly calibrated portable atmosphere testing instruments, as reported by SAFETY4SEA. https://safety4sea.com/rmi-beware-of-improperly-calibrated-portable-atmosphere-testing-instruments/
  10. 10 IMO Resolution MSC.370(93), Amendments to the IGC Code (adopted 22 May 2014; applies to gas carriers constructed on or after 1 July 2016), Annex, paragraph 13.6.18. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.370(93).pdf
  11. 11 IMO Resolution MSC.292(87), Amendments to the FSS Code (adopted 21 May 2010), Annex, new chapter 16, paragraph 2.2.3.4. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.292(87).pdf
  12. 12 Republic of the Marshall Islands Maritime Administrator, Marine Notice 7-041-1, Entering enclosed spaces: safety precautions (Rev. Jan/2026), paragraph 1.4.6. https://www.register-iri.com/wp-content/uploads/MN-7-041-1.pdf

Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.

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