Scuba cylinders are high pressure vessels and as such, should be handled carefully and washed after every use, the same way you care for your other pieces of valuable dive equipment.

It is a requirement of Standards Australia that scuba cylinders be visually inspected and undergo a hydrostatic test every twelve months, this way the integrity of your dive cylinder can be maintained.

Pro-Dive Central Coast operate their own in house, Gas Cylinder Hydrostatic Test Station under the name of Central Coast Hydrostatics. Government Test Station #392.

All cylinders for use in storage or filling of breathing air come under a particular Australian Standard and as such should be tested to the applicable standard, i.e., AS 2030.1-1989. This standard specifies requirements for the approval, filling, handling, inspection, testing, storage, inspection, maintenance and transportation of refillable gas cylinders.

When you present your cylinder for filling, it will have to pass all requirements before it can be accepted for refilling. This where you must make certain you look after your cylinder.

A cylinder presented for filling that looks very dirty, dented or appears to have been involved in a fire is very suspect. Fill station staff look at these cylinders very carefully.

When your cylinder undergoes a hydrostatic test, the following will happen;

• The cylinder is decanted to atmosphere.
• Cylinder exterior is inspected for any signs of damage, dents or fire damage.
• The valve and neck O ring are removed
• The cylinder is visually inspected, (particular attention is paid to the neck threads and shoulder).
• Internal buildup or foreign matter is removed by rumbling or wire brush method.
• The cylinder is cleaned and inspected again.
• Cylinder is filled with water, all air bubbles are removed
• Cylinder is pressurised to its test (TP) pressure. (pressure held for 1 minute, allows cylinder to settle down and all expansion to take place)
• Pressure is then released and a gauge is used to determine permanent stretch cylinder has adopted.

This is why cylinders should not be overfilled, allowable stretch is 1/5000th per litre of internal volume.

The cylinder is then emptied and dried with fan forced air, re-inspected visually, stamped with the month and year of test,

Along with Central Coast Hydrostatics serial number test stamp.
New O rings installed,
Valve tightened to specifications,
Test certificate filled out for your records,
Cylinder is then refilled to working pressure.

Scuba divers are advised that all care is taken to protect your equipment, but you are ultimately the person who must initiate the process, any cylinder presented to a fill station must be tested accordingly and as fill operators, if we have any doubts about the integrity of your cylinder, we must follow the guidelines laid down by Fill station managers.

Valves without a burst disc will not be filled.
Cylinders out of test date i.e., previous 12 months. Cylinders are filled to their stamped working pressure.

For more information refer to AS 2030.1