Inhouse Dive Cylinder And
Regulator Testing
Now Available
IDEST TEST HOUSE No7P

“You should never underestimate the explosive power of a filled cylinder”

It is easy to get complacent with cylinders they can get exposed to all sorts of abuse including excessive heat and physical damage.

Make sure your cylinders are properly serviced and protected.
Cylinders need to be visually tested every 2½ years and Hydraulic tested every 5 years.

All testing must be undertaken by a qualified and experienced technicians who must follow a set procedure as follows:

Visual Inspection (every 2.5 years)

Essentially this test is a detailed visual inspection, both internal and external with the following failure criteria:

• Bulge - all fail.
• Dent - fail if any greater than 2 mm.
• Wear - reduction of wall thickness greater than 25%.
• General Corrosion - reduction of wall thickness greater than 20% OR where original surface is not visible.
• Area Corrosion - (i.e., where corrosion is limited to less than 20% of surface) a reduction of wall thickness greater than 25%.
• Isolated pitting - Reduction of wall thickness greater than 40%.
• Thread damage - all physical damage or imperfections (recutting of threads can be achieved up to a maximum tolerance ).
• Weight Check - Weight of cylinder ( minus valve ) less than 95% of the tare weight stamped on the cylinder.
• Removal of the tank boot, bands and valve.
• The exterior of the tank is then inspected for impact damage and corrosion.
• The interior of the cylinder is examined using a special endoscope.
• Dental mirrors may enable the inspector to examine the area around the inside of the tank neck.
• The valve is checked for smooth operation and its threads lubricated to help prevent galvanic action between the dissimilar metals of the tank and valve.
• Valves may also require periodic overhauls, just like scuba regulators.
• If no corrosion or damage is detected, the cylinder is reassembled and filled.
• A sticker is then placed on the tank which identifies the facility providing the inspection and the month and year in which the inspection was done.
• If damage or corrosion is detected, the technician will decide upon an appropriate course of action.
• Minor scale or the presence of contaminants on the inside of an aluminium cylinder can usually be removed by rinsing with distilled water and drying with warm air.
• Minor oxidation on the inside of a steel cylinder may be best left untreated due to the fact that the process of removing it might actually weaken the cylinder more than the oxidation itself.
• Extensive oxidation or deep pitting is treated by degrees of sand blasting.

Hydraulic Testing

In this test the cylinder is filled with water and then placed inside a water-filled, high-pressure chamber. The water pressure inside the cylinder is then increased to five thirds of it's maximum working pressure. This is sufficient to cause the cylinder to expand slightly. This expansion causes the water outside the tank to be displaced and this is channeled into marked collection tubes that allow it to be measured. If the tank's expansion is within acceptable limits (< 5%), it successfully passes the test. If not, the tank may not be refilled.

After pressure testing, tanks that pass are cleaned and dried, then stamped with the current month and year and the tester's initials.

Labelling and marking

The test date stamp must now read YYYY/MM and be punched into the neck of the cylinder it is also mandatory to mark the cylinder with a punch-out sticker to make it easy to see when the cylinder is next due for test .

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