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Testing of Breathing Gas

Many people will have seen the recent unfortunate incident where a number of school children have been hospitalised after a diving lesson and the subsequent urgent message from the HSE regarding breathing gas from Aqualogistics in Stockport.

The Diving Standards Team wish all service divers to be reminded about the importance of testing breathing gas in accordance with the standards in JSP319 and BRd2806(5).  Specifically the following should be complied with:

  • All breathing gas requires an annual laboratory test at a UKAS accredited lab to BS EN12021:2014.
  • Three monthly tests are also required to comply with  HSE DVIS No.9 (Rev. 1)
  • Non-service compressors need a before use test using the Factair F2235
  • Expeds and Branches should also remain vigilant and if any compressor maintenance is observed or divers report feeling ‘unwell’ then CNBA should be re-tested to confirm the quality of the gas before the start of any dive evolution

Recent expeds have also highlighted the following items in their PXRs which may help with transporting and using the Factair F2235:

  • Transport the FACTAIR F2235 as hand luggage and NOT hold luggage.
  • Print off a copy of the FACTAIR F2235 operating instructions from the FACTAIR website in case you are challenged on what the kit does
  • If you are transporting the FACTAIR F2235 through a ‘FRAGILE’ country and you feel the equipment might be challenged have the ‘purpose of the FACTAIR’ translated into the local language to ease security clearance.
  • When ‘testing’ CNBA in countries with high humidity remember to run the compressor for longer or have the owners change the filters if you are struggling to meet the ‘water content’ of the BS EN12021:2014.
  • Order enough DRAGER sampling tubes which are ‘in-date’ and keep them in a refrigerator if in hot climates.
  • The purpose of the 5 minute ‘run through’ at 2 bar prior to the test is to ensure all moisture has been removed.
  • You have more tolerance on ‘water vapour’ at a lower cylinder pressure (<200 bar 50mg/m3 or >200 bar 35mg/m3)

More information on gas testing is contained in BRd 2806(5) and Annex K has details of the Factair F2235


Unserviceable Analox Oxygen Analysers (O2EII)

The Analox Oxygen Analyser (O2EII) is used in conjunction with the Factair F2235 to test breathing gas and should be held by all service diving branches.  Annex K to BRd 2806(5) provides full details of how they can be demanded through the stores system including the NSN.

A number of units have reported that they have received unserviceable Analox Oxygen Analysers.  This is due to the oxygen cells which form a key component of the analyser reaching the end of their shelf life.    Fortunately replacement cells can also be demanded through the stores system using the NSN 6515-99-1485260  and then replaced by users.

The manufacturer has provided a video on youtube which shows how this can be done:

Issues With Loan Pool Equipment

During the Q&A session at the end of the JS Diving Safety Conference, it became apparent that some units and expeditions had encountered problems with diving equipment issued from the AT Loan Pool at Bicester.  A number of these have also been highlighted in PXRs and JS Incident Reports.


These incidents are now being actively investigated by ATG(A) who are putting in place measures to ensure that they do not happen again.

In order to reduce the risk of future issues and ensure that issues identified on expeditions are addressed, ATG(A) have asked that units and expeds are reminded of the following:

  • Units/expeditions collecting equipment from the loan pool are to send an SME with a minimum qualification of Dive Leader.  Without this equipment will not be issued.  For units wishing to draw a FACTAIR F2235 then proof of training will be required.
  • Equipment faults are to be highlighted using the procedures in AGAI Volume 1 Chapter 11 (link requires Defence Gateway account).  The full text is copied below:

11.123. Equipment Damage Reports.  Incidences of any damaged or failed equipment must be notified to the unit QM who is to conduct an investigation, or, in serious circumstances or in cases of serious injury, convene a Board of Inquiry. Damage Reports are to be included in the Post Exercise Report (PXR) and also reported through the appropriate Formation ATDO to HQ ATG (A) as soon as possible. Equipment involved in any accident or incident where an investigation is likely must be withdrawn and secured for the investigation by the unit. The balance of stores is to be returned on time with a letter of explanation (copied to HQ ATG (A)).


CNBA Oxygen Content Analysis

A recent International Marine Contractors Association (IMCA) safety flash (01/16) contains details of an incident where a commercial diver collapsed due to low oxygen content of what was believed to be air which was supplied to  him.   Fortunately this occurred on the surface and there was no long term impact.

This incident is a useful reminder of the importance of testing diving gas before use.

As most service divers should be aware, it is mandatory for testing of Compressed Natural Breathing Air (CNBA) used by AT divers to be completed using a FACTAIR F2235.  As part of this test, the oxygen content should also be tested using an Analox Oxygen Analyser and this forms part of  the FACTAIR F2235 kit.

The oxygen content is then recorded on the test form (either included with the kit or downloadable from the FACTAIR website) which needs to be sent to the Diving Standards Team (DST).

It is hoped that by the use of the FACTAIR F2235 and Analox Oxygen Analyser incidents like that above can be avoided by AT divers.



Updated FACTAIR F2235 Operating Manual

The manufacturer of the FACTAIR F2235 breathing gas testing device has just produced a revision to the manual which is now available to download from their website. The latest manual is dated March 2015 and previous versions should now be replaced.

Link –


Gas Testing with FACTAIR F2235

In order to comply with the regulations concerning testing of breathing gas used for sub aqua AT it is necessary to use the FACTAIR F2235 gas testing kit.  In order to bring together information relating to the demand process, support arrangements and the training process for this equipment, 2015DIN04-078 has just been published on the Defence Intranet .

[Updated May 2016 – The DIN is now incorporated into BRd 2806(5) as Annex K]