EQUIPMENT SERVICING AND TECHNICAL DEPARTMENT

Hydrostatic Testing

All cylinders must pass a hydrostatic test every five years. The test date is permanently stamped on the cylinder if it passes inspection. In this example, the test was performed in June of 2001. A plus "+" symbol following the test date indicates the cylinder can be filled 10% higher than the stated maximum service pressure. Because this test is performed every five years, the cylinder may have several hydro dates stamped on the cylinder.

The simple explanation, for testing, is safety for the public, the cylinder filling technician and the transportation of potentially explosive high pressure vessels over our highways. Although cylinders are made of non-shatterable metal, they still can tear apart with explosive force, fire off the valve, spin or take off at high speeds through walls, causing severe bodily harm, death and destruction.

The hydrostatic test actually measures the elastic expansion of the metal and its ability to return to its original shape within 10 percent of the original volume. The water test is safe since it cannot compress or expand like air. If the cylinder leaks or blows out, it leaks a stream of water and the worst case scenario is a water jacket’s copper gasket breaks allowing water to spray everywhere.