Appendix – Control of Gas Cylinders (see 6.1.8)
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1328 – Guidelines for the Approval of Inflatable Liferafts Subject to Extended Service Intervals Not Exceeding 30 Months – (11 June 2009) - Annex – Guidelines for the Approval of Inflatable Liferafts Subject to Extended Service Intervals Not Exceeding 30 Months - Appendix – Control of Gas Cylinders (see 6.1.8)

Appendix – Control of Gas Cylinders (see 6.1.8)

  1 All gas cylinders should be weighed and checked against the gross mass which has been marked on the bottle. To allow for difference of scales when check-weighing, a tolerance of 14 g should be permitted. No gas cylinder should be fitted unless it has passed one of the following two tests:

  • .1 A storage period of at least 30 days after filling. Weighing should take place before and after storage using the same scales. There should be no loss of weight.

  • .2 The leak test specified in paragraph 2.

  2 This paragraph describes a leak test for CO2 cylinders which is regarded as equivalent to weighing the filled cylinder before and after at least 30 days of storage.

  • .1 Materials required

    • .1 Polythene bags of a suitable size to fit over the head of the cylinder, e.g.:

      • .1 for a 125 mm diameter cylinder the bag size is approximately 230 mm open width x 300 mm length;

      • .2 for a 100 mm diameter cylinder the bag size is approximately 165 mm open width x 300 mm length; and

      • .3 for a 90 mm diameter cylinder the bag size is approximately 150 mm open width x 300 mm length.

    • .2 Elastic bands of a suitable size.

    • .3 A measuring glass, capacity 25 ml.

  • .2 Test solution

    • .1 The test liquid should be the standard test solution used to indicate small amounts of CO2 gases (0.004N sodium carbonate in a 2% weight/volume solution of phenolphthalein).

    • .2 The solution should be stored in a cool place in dark coloured glass bottles with a tight-fitting screw cap. The shelf life should not exceed 12 months.

  • .3 Method of testing

    • .1 Lay the cylinder to be tested on its side in a rack, such that the valve end is protruding. Make sure the valve and shoulder of the cylinder are free from dust and other contaminants by carefully wiping it with a clean, dry cloth. Remove the dust cap to clean the valve, then replace the cap loosely.

    • .2 Using the measuring glass, transfer 25 ml of the test solution into a polythene bag.

    • .3 Pass the open end of the bag over the valve head and attach it to the cylinder body using one or more elastic bands. Make sure there are no air gaps in the seal.

    • .4 The polythene bag should hang 20 cm off the valve end of the cylinder with the test solution in one corner.

    • .5 Maintain the test for a period of not less than one hour.

    • .6 After the period of time stated in 2.3.5, shake the solution gently and make the observations detailed in 2.4.

    • .7 A control sample is necessary to detect any contamination. The sample is made by pouring 25 ml of test solution into a bag which is not fitted to a cylinder, but is sealed at the open end with adhesive tape to exclude atmospheric contamination. This bag should be placed on the rack in the vicinity of the cylinders being tested.

  • .4 Observations

    • .1 A leak of carbon dioxide from the cylinder will cause the pink colour of the test solution to fade. The test solution will become clear as water.

    • .2 If no colour change is observed, there is no leak of gas from the cylinder.

    • .3 The control sample should not change colour during the test. If a colour change takes place, this indicates that the atmosphere in the test area is contaminated with carbon dioxide and tests carried out together with this control sample are invalid. Tests should be repeated after corrective action has been taken on the atmosphere.

Parent topic: Annex – Guidelines for the Approval of Inflatable Liferafts Subject to Extended Service Intervals Not Exceeding 30 Months
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