© Copyright 2003-2019 Dive Lab® Inc. All rights reserved.
This Guide is made available for the express use of owners and users of the Dive Lab XLDS systems.
This information is subject to periodic updates and changes. Always check the Dive Lab web site for the latest versions.
Document XLDS Guide – Section Four A
Revised September 30, 2019
12
SECTION FOUR A: RDC REPAIR / MAINTENANCE / OVERHAUL
minor pipe thread fitting leaks will not suddenly
or drastically increase because of the natural
locking nature of pipe threads. Teflon tape is used
both as a lubricant and a sealant. As a lubricant,
the tape keeps the threads from galling. As a
sealant the tape produces a gas tight seal. Unlike
pipe fittings, minor Leaks in O-Ring fittings cannot
be tolerated, because the seal is made by the O-
Ring only, between two surfaces and leakage will
normally increase rapidly especially if there is any
movement of the fittings. In some cases, parts of
the O-Ring may extrude causing sudden massive
leakage or total failure of the O-ring seal.
Unlike O-rings, the pipe threads use sealing tape
which will usually show up as a minor leak and
will not progress significantly as long as there is
no movement of the fitting. Very minor leakage
in pipe thread fittings is common, should be
expected, and does not pose an operational
hazard in “AIR SYSTEMS”, or a significant
reduction in operational capability as long as the
leaks are minor, can be identified and quantified.
All leaks should be repaired as soon as possible /
practical. It should be understood, that in
portable fast response systems like the XLDS
which can be subjected to shock and vibration
during transport minor leaks may result that may
have to wait before repairs can be made.
The only way to remedy leaks in pipe thread
fittings,
is
to
depressurize
the
system,
disassemble the joint, remove old sealing tape,
brush clean and inspect the threads for damage,
and then re-tape and re-make the joint. Because
this is often impractical to accomplish in the field,
minor leakage during system use, can be an
acceptable alternative to field repairs in order to
safely continue with diving operations until re-
sealing can be accomplished.
Checking and Quantifying
Leaks
There is a full system step by step test procedure
for pressure testing. XLDS RDC Console Annual
Pressure /joint Tightness Testing Test which
should be done annually, but can also be done at
any time leakage is suspected. However, as a
quick field check if necessary, complete a check
as described herein to quantify leakage.
Checking for Leaks Quick Check: To check for
leaks, ensure the umbilical supply valves,
pneumofathometer valves, and cross connect
valves are shut, then slowly open each cylinder
HP supply valve, and each supply block valve
approximately 1/4 -1/2 turn, and pressurize each
HP circuit, using at least a 3000 PSIG supply
pressure. Load each regulator to 350-400 PSIG
and allow the system to settle for at least one
minute then secure the cylinder valves only, and
record the high and low pressures and the time.
Allow the system to sit for ten minutes, then
check the gauges. If there has been any loss of
pressure, apply soapy water solution to all joints
and fittings to identify the leaks. Very minor leaks
at pipe threaded joints, that cause a drop of
gauge pressure of no more than 10 PSIG in ten
minutes, with the supply isolated at the HP blocks
as noted on each of the high-pressure gauges, do
not require immediate re-sealing. Pressure loss in
excess of 10 PSIG, represents a gas loss in excess
of 3 liters in ten minutes, and should be corrected
before the system is used. This leakage is
acceptable for pipe thread fittings and joints only,
WARNING
Never tighten fittings or components while the
system is pressurized. Attempting to tighten
fittings, while the system is pressurized, could
result in component failure, resulting in
serious injury or death.
