Cell biology (formerly called cytology, from the Greek ÎºÏÏÎ¿Ï, kytos, vessel) is a branch of biology that studies the different structures and functions of the cell and focuses mainly on the idea of the cell as the basic unit of life.
(B) For a cylinder having a water capacity over 12 pounds-- (1) By hydrostatic test without determination of expansion (modified hydrostatic test method). A retest must be performed 12 years after the original test date and at 7-year intervals; or (2) By hydrostatic test using the water jacket method. A retest must be performed 12 years after the original test date and at 12-year intervals thereafter.
Well, the good news is that with proper care and maintenance, your portable fire extinguisher should last a very long time. If youâve had the same fire extinguisher for a long time (10 â 12 years) it is recommended that you have it hydrostatically tested. A hydrostatic test exposes your fire extinguisher to high pressure (usually 500psi) to check the integrity of the shell. If the shell holds up well it is a sign that your fire extinguisher is still good and will last for a few more years before it needs to be replaced.