[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: CO2 cylinders
>Hydro is short for hydrostatic test. A cylinder/bottle is
>filled with water and pressurized to a given pressure to see
>if integrity is still within safe limits. I do not know
>what the pressure the bottles are taken to is. Water is
>used because it does not compress well, thus if a rupture
>occurs, the bottle will crack or just leak, not violently
>explode. Most privately owned gas cylinders must be tested
>every 12 months to comply with DOT/state/fed regulations.
>Many "filling stations" won't fill a bottle that is "out of
>hydro".
Cylinders are tested by filling them with water and pressurizing them
to 5/3 of their rated maximum pressure (the pressure is stamped on the
cylinder after the DOT specification number). For example, a cylinder
rated at 3,000 psi would be tested at 5,000 psi. At the testing
pressure, the cylinder expands slightly. According to DOT
regulations, a permanent expansion of 10 percent or more of the total
expansion at the testing pressure indicates that the cylinder is
unsafe for use and must be destroyed. Typically, cylinders that fail
have several holes drilled into them by the tester so they cannot be
used again.
DOT (Department of Transportation, a Federal agency) requires
cylinders to be hydrostatically tested every FIVE years. Most
ruptures occur during refilling, so a wise supplier will not fill a
cylinder with an expired hydro.
Regards,
Mark