Technical Information Sheets  

These information sheets have been produced as a result of visits and inspections to various IDEST Test Centres.  The inspectors have identified aspects of the work involved that clearly need further clarification or guidance.

The sheets are here to help technicians get a better understanding of the field of work they are involved with so as to provide customers with the highest possible quality of workmanship, knowledge and expertise.

  T1  Personal Protective Equipment - T001

Guidance on the need and use of Personal Protective Equipment in the workplace at all times when inspecting and testing diving cylinders.


T2 Sheet  Gauge Calibration Sheets - T002
Guidance on how to create calibration sheets when comparing the master gauge pressures with those of the  working gauge.  It is essential to have an accurate working gauge when hydraulically testing cylinders and having a regular check against the master gauge is the way forward.


  T3 sheet  Oxygen Cleaning of Diving Cylinder - T003
Guidance on the process of oxygen cleaning of diving cylinders for the use of Nitrox and Trimix breathing gases.  There are several methods of cleaning diving cylinders.  This sheet provides suitable guidance.


T4 sheet    Cylinder Stamping - T004
Guidance on the correct format for stamping diving cylinder after they have been hydrostatically tested.  BS EN ISO 13769:2018 is the standard to which technicians should be stamping cylinder.  Does your stamping format comply with that international standard as it should do?  In April 2019 IDEST, in agreement with other government agencies, agreed to drop the use of the letter 'V' for PIs and hard stamping of cylinders.


T5 sheet    Thread Gauge Classes - T005
Guidance on the classes of thread gauges to use when inspecting or testing cylinders and cylinder valves.  It is essential that the correct class and size of gauge is being used to check valve and cylinder threads.  Using the wrong class and size can result in cylinders passing when they should not and vice versa.


T6 sheet    Valve Maintenance at time of inspection - T006
Guidance on what maintenance must be done at the time of inspecting a diving and breathing gas cylinder. BS EN ISO 22434:2011 superseded BS 14189 and states that when a valve is removed from a cylinder it must be inspected.  This involves dismantling the valve, cleaning it and replacing parts.


T7 sheet    Valve/Cylinder mismatch by THREAD - T007
Guidance on the actions to take when there is a valve to cylinder thread mis-match.  This can be an M25 valve being fitted to a G 3/4" cylinder thread and vice versa.  This is potentially a dangerous practice and must be dealt with correctly.


  T8  Valve/Cylinder mismatch by PRESSURE - T008
Guidance on the actions to take when there is a pressure valve to cylinder mis-match.  This can occur when a valve rated at 232 bar is fitted to a cylinder that is itself rated to 300 bar.  Similarly when a valve rated at 300 bar is fitted to a cylinder only rated to 232 bar.


    APEKS-AP1158  availability - T009
Guidance on the availability of spare parts for some APEKS cylinder valves.  What is available and what is not available from the manufacturers.

  T10  Shore Hardness explained - T010
This information sheet explains the origin of Shore Hardness and its reference to 'O' rings used in diving and breathing apparatus cylinders.


  T11  Using UKAS Accredited Calibration Houses - T011
Measurement equipment that has a significant influence on the results of the inspection, needs to be calibrated before being put into service, and thereafter calibrated according to an established programme.


  T12 Understanding Calibration Certificates - T012
Many Test Centre staff do not fully understand the information that is contained on a calibration certificate.  This information sheet explains the need for understanding the data and what to gain from the readings provided.


T013 Extending Thread Gauge Calibration Period - T013
Due to the reduced use of some thread gauges on threads such as G3/4", IDEST has introduced an extension system to the annual recalibration period for thread gauges.  This Information Sheet explains the system for applying for an extension on the calibration periods of thread gauges dependent on usage.


  Hydro or Visual? - Can't decide - T014

Quite often when a cylinder comes in for a visual it may have missed the anniversary date by some time.  Technicians often advise their customer that because it has missed the visual it must have a hydro.  This is not necessarily the case. This T014 explains how to make the decision if a cylinder has missed a visual inspection date.


Quadrant Labels for Visuals & Hydros - T015
IDEST changed the colour of the quadrant label to be used for visual inspections to green.  While the blue label will be used for hydro tests only. This technical information sheet explains the changes and what to do for each of the inspection and tests.


Safety first in the workplace at all times...


Page last updated 24/03/21