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.
Seven of these are: 1  Hydrostatic testing, which uses water or another liquid under pressure. 2  Pneumatic or gaseous-fluid testing, which uses air or another gas under pressure. 3  A combination of pneumatic and hydrostatic testing, where low pressure air is first used to detect leaks. Initial service testing, which involves a leakage inspection when the system is first put into operation. Vacuum testing, which uses negative pressure to check for the existence of a leak.