TB 5-4220-200-12-1
h.
New Tank Inspection. A brand new tank sometimes will have factory slag on the walls in small patches.
The patches of slag are areas that were missed when the tank was sand blasted. Slag is created when
the tank is galvanized on the outside. It is heated to about 850. If there is any foreign material in the tank.
it will be fried and become very harsh material on the walls. The material will slowly, but surely. come off
over a period of time. It may take years to completely come out of the tank. When it flakes off the tank,
it travels through the valve, up into the regulator and damages the valve seats.
i.
Carbon in Tanks. If the inside of the tanks is dry and black, it is covered with carbon. A very close look
at the carbon on the bottom will detect a sparkle. The carbon is actually activated charcoal that has come
from a compressor filter. The top of the filter must be packed very well with a material that will not allow
the loose fine charcoal to travel through the compressor system. This problem does not exist with car-
tridge type filters.
Carbon is not detrimental to the tank, but is to the valve and regulator. Carbon will eventually build up on
internal moving parts and block valves from closing.
Internal Cleaning. If following the inspection it is determined that a tank requires internal cleaning and
j.
hydrostatic testing it must be evacuated to a higher level of maintenance. Commercial facilities qualified
to provide these services may be utilized.
k.
Recording the Inspection. After the tank has been inspected prepare an entry in the user's equipment
record containing the following minimum information:
(1)
Date of Inspection (Day, month, and year).
(2) Inspector's Identification.
(3)
The statement "This SCUBA Tank has been visually inspected and shows no significant corrosion.
or mechanical defects."
(4)
Signature of the inspector.
I.
Contaminated Valves. The tank valve is a natural trap for rust and salt. Even though a tank is cleaned,
rust or salt may be trapped in the valve passages. During operation, these remaining particles in the valve
may loosen and travel into the regulator and cause damage to internal parts, Therefore, if any loose de-
posits are found in the tank, the valve should be disassembled, cleaned, lubricated, and defective parts
replaced. This will insure a clean system throughout,
m.
Installing Manifold After Tank Inspection. Reassemble and install the valve manifold assembly in accor-
dance with paragraph 4-16 or 4-17.
NOTE
If a valve is too tight to screw in by hand, a wrench should NOT be used to start
it down. It is an O-Ring seal and the threads on the tank should be retapped. If
a wrench is used to force the valve in, the threads on the brass valve will be
stripped. If full air pressure is put into a tank with a valve that has stripped threads,
the valve may be forced out. The same care should be used when installing a
valve in an aluminum tank.
Teflon tape should not be wrapped around valve threads that have an O-Ring
seal. The teflon will not form a seal. Small pieces of teflon can get into the valve
and regulator and under valve seats.
n.
Reassembly of Twin Tank Block. Install bands. hardware, twin tank harness and reserve valve rod and
clips in accordance with paragraph 4-16 or 4-17.
4-28
