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.
Fire Extinguisher Hydro Testing. Fire extinguishers should last a very long time, but let's face it â nothing's perfect. If your fire extinguisher is more than 12 years old, call National Fire Protection for a fire extinguisher hydro test today! A fire extinguisher hydro test will make sure the shell of your fire extinguisher has no cracks or leaks that can cause it to malfunction when you need it most.