DAN has learned of at least 8 or more recent cases of failure in regulators arising from the build-up of crystals in the second stage hose, where these are constructed using a polymer-braided structure. They intend to publish a more in depth account of this in the Alert Diver Magazine, written by Francois Burman, a professional engineer on the DAN staff, but this safety-related issue needs to be brought to the more urgent attention of both divers and diving equipment service providers.
The following notice has been extracted from the full article:
- All regulator hoses, including braided hoses, have a limited service-life – irrespective of the external appearance, or the reinforcement and protection provided by hose protectors or the braiding itself. Prior to 2010, the stated service life of 5 years or 500 dives for braided hoses appears to be inaccurate; failures have occurred in hoses with less than 4 years of in-service life. After this date, the manufacturers appear to have made satisfactory changes.
- The inside lining of all hoses appears to be uniquely prone to degradation in the form of 'crystallisation’, especially in hot, tropical locations. This is a gradual process, reportedly especially active in the range of 27° - 32°C, but the disruption of gas-flow and regulator function is unpredictable and invisible to external inspection.
- Any sign of gas-flow restriction in the regulator assembly should prompt careful inspection of the regulator and the hose. If the regulator is not the cause, suspect the hose.
- A physical examination including squeezing the hose every couple of inches to assess whether the hoses exhibits the same degree of flex should indicate if all is well. Any indication of a change in the resistance.
Remember if in doubt have your regulator serviced by a certified technician.