As cylinders are classed as pressure vessels they are required by legislation to be inspected and tested at regular intervals by an accredited testing station.
Accreditation in the UK is subject to (independent) accreditation either by:
- A United Kingdom Accreditation Service (UKAS) approved centre or
- An Inspectorate for Diving Equipment Servicing and Testing (IDEST) approved centre - IDEST operate within the UKAS scheme
One of the reasons the accreditation process was brought in was to assure the safety of the inspection and the competence of the operator to prevent the risk of failure, with catastrophic consequences.
Where a person filling cylinders is ‘at work’, such as in a dive shop, then there is specific legislation for checking cylinder inspection and test regimes. This means that centres are extremely unlikely to fill cylinders that haven't been tested by an accredited testing station.
Although the legislation doesn't apply to non-commercial activities, it is still important to protect people filling cylinders which is why BSAC Safe Diving states that only cylinders in test should be filled by branch compressors.
