A temperature relief plug, fusible at 203ƒF, is installed at the bottom of the tank, in contact with the AFFF. Each
system is equipped with a N2 pressure regulator preset at the factory to reduce N2 pressure to 220-240 PSI. A
nonadjustable pressure relief valve, preset to 250 PSI, is installed on the plumbing of each tank in case of a
complete regulator failure.
(3) Two nitrogen (N2) cylinders. When fully charged, contain 300 cubic feet of N2 at 2400 PSI. A
minimum of 1750 PSI is required for operation. Each cylinder is equipped with a quick-opening lever and a 0-
3,000 PSI gage installed on the valve.
(4) Hose assembly (twinned handline). This transmits the agents from the tanks to the twinned
discharge nozzle assembly. The assembly consists of two, 150-foot non-collapsible hoses, encased in a woven
polyester jacket. Also it has a wheeled remote hose cart with an additional 150 feet that can be connected to the
mounted reel to extend its capability to 300 feet.
Health Hazards. Health hazards are inherent in petroleum products. You cannot eliminate them, but you
must be aware of them and use precautions. Most petroleum health hazards can be classified according to the
form the contaminant takes.
a. Dusts. These are solid particles of substances that result from mechanical operations such as
grinding, scraping, buffing, cutting, drilling, sanding, or sand-blasting. Dusts are divided into three types:
(1) Toxic dusts injure the organs and tissues of the body when they are inhaled into the lungs. If
ingested into the digestive system, they attack the body through the liver. Certain toxic dusts may also irritate the
skin. Lead, manganese, mercury, arsenic, and their compounds make toxic dusts. One of the most toxic is
produced when cleaning and repairing tanks that contained leaded gasoline. Lead dust and fumes also result from
burning sludge from leaded gasoline. The body can resist lead poisoning if it is given enough time between
exposures. Personnel should be tested periodically for lead poisoning.
(2) Fibrosis producing dusts injure the lungs in such a way that normal tissue is replaced with fibrous
or scar tissue. The most common is dust containing silica, from grinding and polishing machines or sanding and
sandblasting equipment. It causes the disease called silicosis.
(3) Nuisance dusts may not cause severe injury, but they may cause inflammation and respiratory
ailments. Personal allergies may add to the effect of dusts.
b. Gases and Vapors. The term "gas" and "vapors" are often used to mean the same thing, although
there is a difference. A gas exists as a gas at ordinary temperature and pressure. A vapor is a gas-like form of a
substance that is ordinarily a solid or liquid. Gases and vapors are divided into four groups.
(1) Poisonous or Toxic -- have various effects on the body. They may injure or destroy the visceral
(intestinal) organs, the blood-forming system, tissues, or bones. Toxic effects often show up only after prolonged
exposure. The most poisonous are hydrogen sulfide (found in crude oils with high sulfur content) and
tetraethyllead (found in leaded gasoline). You must avoid exposure to them at all times, because they can kill
you. Personnel exposed to hydrogen sulfide may lose consciousness and never regain it. Other gases, listed in
order of toxicity, are sulfur dioxide, ammonia, methyl bromide, butane, propane, and the freons. These gases are
often used as refrigerants.